这一章我们开始分析ActivityManagerService，在后面的介绍中，我们简称为AMS。AMS并不是只用于管理所有的Activity的生命周期，它同时也管理着系统的service、broadcast以及provider等。我们首先还是从AMS的启动开始分析，它的构造以及运行都是在SystemServer当中：
context = ActivityManagerService.main(factoryTest); ActivityManagerService.setSystemProcess(); ActivityManagerService.installSystemProviders(); ActivityManagerService.self().setWindowManager(wm); ActivityManagerService.self().systemReady(new Runnable() ActivityManagerService.self().startObservingNativeCrashes();
在SystemServer当中主要调用AMS的上面几个方法，其中通过AMS的main方法返回的context提供给其它Service上下文使用。我们接下来一个个分析上面几个函数，首先来看main方法：
ActivityManagerService的main方法
public static final Context main(int factoryTest) {
AThread thr = new AThread();
thr.start();
synchronized (thr) {
while (thr.mService == null) {
try {
thr.wait();
} catch (InterruptedException e) {
}
}
}
ActivityManagerService m = thr.mService;
mSelf = m;
ActivityThread at = ActivityThread.systemMain();
mSystemThread = at;
Context context = at.getSystemContext();
context.setTheme(android.R.style.Theme_Holo);
m.mContext = context;
m.mFactoryTest = factoryTest;
m.mIntentFirewall = new IntentFirewall(m.new IntentFirewallInterface());
m.mStackSupervisor = new ActivityStackSupervisor(m, context, thr.mLooper);
m.mBatteryStatsService.publish(context);
m.mUsageStatsService.publish(context);
m.mAppOpsService.publish(context);
synchronized (thr) {
thr.mReady = true;
thr.notifyAll();
}
m.startRunning(null, null, null, null);
return context;
}
AThread继承于Thread，主要用于初始化Looper并构造AMS对象赋值给它的成员变量mService，我们首先来看AMS的构造函数：
private ActivityManagerService() {
Slog.i(TAG, "Memory class: " + ActivityManager.staticGetMemoryClass());
mFgBroadcastQueue = new BroadcastQueue(this, "foreground", BROADCAST_FG_TIMEOUT, false);
mBgBroadcastQueue = new BroadcastQueue(this, "background", BROADCAST_BG_TIMEOUT, true);
mBroadcastQueues[0] = mFgBroadcastQueue;
mBroadcastQueues[1] = mBgBroadcastQueue;
mServices = new ActiveServices(this);
mProviderMap = new ProviderMap(this);
File dataDir = Environment.getDataDirectory();
File systemDir = new File(dataDir, "system");
systemDir.mkdirs();
mBatteryStatsService = new BatteryStatsService(new File(
systemDir, "batterystats.bin").toString());
mBatteryStatsService.getActiveStatistics().readLocked();
mBatteryStatsService.getActiveStatistics().writeAsyncLocked();
mOnBattery = DEBUG_POWER ? true
: mBatteryStatsService.getActiveStatistics().getIsOnBattery();
mBatteryStatsService.getActiveStatistics().setCallback(this);
mProcessStats = new ProcessStatsService(this, new File(systemDir, "procstats"));
mUsageStatsService = new UsageStatsService(new File(systemDir, "usagestats").toString());
mAppOpsService = new AppOpsService(new File(systemDir, "appops.xml"));
mGrantFile = new AtomicFile(new File(systemDir, "urigrants.xml"));
mHeadless = "1".equals(SystemProperties.get("ro.config.headless", "0"));
// User 0 is the first and only user that runs at boot.
mStartedUsers.put(0, new UserStartedState(new UserHandle(0), true));
mUserLru.add(Integer.valueOf(0));
updateStartedUserArrayLocked();
GL_ES_VERSION = SystemProperties.getInt("ro.opengles.version",
ConfigurationInfo.GL_ES_VERSION_UNDEFINED);
mConfiguration.setToDefaults();
mConfiguration.setLocale(Locale.getDefault());
mConfigurationSeq = mConfiguration.seq = 1;
mCompatModePackages = new CompatModePackages(this, systemDir);
// Add ourself to the Watchdog monitors.
Watchdog.getInstance().addMonitor(this);
}
PMS的构造函数主要初始化一些成员变量，并在/data/system下面建立一些文件(夹)供系统统计数据用，现将一些文件及其作用列在下面的表格中，我们以后使用在再来分析：
| Service | 文件路径 | 描述 |
| BatteryStatsService | /data/system/batterystats.bin | 管理电池使用状态 |
| ProcessStatsService | /data/system/procstats | 管理进程状态 |
| UsageStatsService | /data/system/usagestats | 管理用户使用状态 |
| AppOpsService | /data/system/appops.xml | 管理进程状态 |
| AtomicFile | /data/system/urigrants.xml | 管理系统URI权限 |
回到main方法中，接着调用ActivityThread的systemMain方法去构造一个ActivityThread对象，ActivityThread是所有Application运行的主线程。这里通过systemMain去获得一个SystemContext，而一般应用程序则通过ActivityThread的main方法开始执行，我们将在后面分析到：
public static ActivityThread systemMain() {
HardwareRenderer.disable(true);
ActivityThread thread = new ActivityThread();
thread.attach(true);
return thread;
}
private void attach(boolean system) {
sCurrentActivityThread = this;
mSystemThread = system;
if (!system) {
} else {
android.ddm.DdmHandleAppName.setAppName("system_process",
UserHandle.myUserId());
try {
mInstrumentation = new Instrumentation();
ContextImpl context = new ContextImpl();
context.init(getSystemContext().mPackageInfo, null, this);
Application app = Instrumentation.newApplication(Application.class, context);
mAllApplications.add(app);
mInitialApplication = app;
app.onCreate();
} catch (Exception e) {
throw new RuntimeException(
"Unable to instantiate Application():" + e.toString(), e);
}
}
ViewRootImpl.addConfigCallback(new ComponentCallbacks2() {
@Override
public void onConfigurationChanged(Configuration newConfig) {
synchronized (mResourcesManager) {
if (mResourcesManager.applyConfigurationToResourcesLocked(newConfig, null)) {
if (mPendingConfiguration == null ||
mPendingConfiguration.isOtherSeqNewer(newConfig)) {
mPendingConfiguration = newConfig;
sendMessage(H.CONFIGURATION_CHANGED, newConfig);
}
}
}
}
@Override
public void onLowMemory() {
}
@Override
public void onTrimMemory(int level) {
}
});
}
在ActivityThread的systemMain方法中，首先构造一个ActivityThread对象，然后调用它的attach方法。传入到attach方法的参数为true，我们先只看attach system的ActivityThread的流程。attach方法首先构造一个ContextImpl对象，然后调用getSystemContext来获取一个SystemContext上下文，这里成为SystemContext是因为它加载了系统中包名为"android"的应用，也就是framework-res.apk，并且mSystemContext会返回给systemServer中其它的服务使用：
public ContextImpl getSystemContext() {
synchronized (this) {
if (mSystemContext == null) {
ContextImpl context =
ContextImpl.createSystemContext(this);
LoadedApk info = new LoadedApk(this, "android", context, null,
CompatibilityInfo.DEFAULT_COMPATIBILITY_INFO);
context.init(info, null, this);
context.getResources().updateConfiguration(mResourcesManager.getConfiguration(),
mResourcesManager.getDisplayMetricsLocked(Display.DEFAULT_DISPLAY));
mSystemContext = context;
}
}
return mSystemContext;
}
首先来看一下ContextImpl的createSystemContext方法：
static ContextImpl createSystemContext(ActivityThread mainThread) {
final ContextImpl context = new ContextImpl();
context.init(Resources.getSystem(), mainThread, Process.myUserHandle());
return context;
}
final void init(Resources resources, ActivityThread mainThread, UserHandle user) {
mPackageInfo = null;
mBasePackageName = null;
mOpPackageName = null;
mResources = resources;
mMainThread = mainThread;
mContentResolver = new ApplicationContentResolver(this, mainThread, user);
mUser = user;
}
在ContextImpl中有很多init函数，我们要根据它的参数来看正确的init函数。这里的init函数主要初始化一些成员变量。然后在getSystemContext构造LoadedApk对象，LoadedApk用于描述一个加载进来的APK文件：
public LoadedApk(ActivityThread activityThread, String name,
Context systemContext, ApplicationInfo info, CompatibilityInfo compatInfo) {
mActivityThread = activityThread;
mApplicationInfo = info != null ? info : new ApplicationInfo();
mApplicationInfo.packageName = name;
mPackageName = name;
mAppDir = null;
mResDir = null;
mSharedLibraries = null;
mDataDir = null;
mDataDirFile = null;
mLibDir = null;
mBaseClassLoader = null;
mSecurityViolation = false;
mIncludeCode = true;
mClassLoader = systemContext.getClassLoader();
mResources = systemContext.getResources();
mDisplayAdjustments.setCompatibilityInfo(compatInfo);
}
然后再调用ContextImpl的init方法来初始化mSystemContext的一些成员：
final void init(LoadedApk packageInfo, IBinder activityToken, ActivityThread mainThread) {
init(packageInfo, activityToken, mainThread, null, null, Process.myUserHandle());
}
final void init(LoadedApk packageInfo, IBinder activityToken, ActivityThread mainThread,
Resources container, String basePackageName, UserHandle user) {
mPackageInfo = packageInfo;
if (basePackageName != null) {
} else {
mBasePackageName = packageInfo.mPackageName;
ApplicationInfo ainfo = packageInfo.getApplicationInfo();
if (ainfo.uid == Process.SYSTEM_UID && ainfo.uid != Process.myUid()) {
} else {
mOpPackageName = mBasePackageName;
}
}
mResources = mPackageInfo.getResources(mainThread);
mResourcesManager = ResourcesManager.getInstance();
CompatibilityInfo compatInfo =
container == null ? null : container.getCompatibilityInfo();
if (mResources != null &&
((compatInfo != null && compatInfo.applicationScale !=
mResources.getCompatibilityInfo().applicationScale)
|| activityToken != null)) {
} else {
mDisplayAdjustments.setCompatibilityInfo(packageInfo.getCompatibilityInfo());
mDisplayAdjustments.setActivityToken(activityToken);
}
mMainThread = mainThread;
mActivityToken = activityToken;
mContentResolver = new ApplicationContentResolver(this, mainThread, user);
mUser = user;
}
这里的mBasePackageName和mOpPackageName都是"android"。回到ActivityThread的attach方法中，接着调用Instrumentation的newApplication构造一个Application对象并将它设置为mInitialApplication，并添加到mAllApplications数组中，由此我们也可以看出，一个ActivityThread（也就是一个进程）中可以运行多个application，这里application都保存在mAllApplications，其中第一个运行的application保存在mInitialApplication。最后调用Application的oncreate方法：
static public Application newApplication(Class<?> clazz, Context context)
throws InstantiationException, IllegalAccessException,
ClassNotFoundException {
Application app = (Application)clazz.newInstance();
app.attach(context);
return app;
}
/* package */ final void attach(Context context) {
attachBaseContext(context);
mLoadedApk = ContextImpl.getImpl(context).mPackageInfo;
}
在ActivityThread的attach方法的最后，向ViewRootImpl注册一个callback用于接收ConfigurationChanged事件（例如横竖屏切换、输入法弹出等），我们将在介绍WindowsManager的时候来分析如果dispatch这些事件到具体的activity当中。回到AMS的main方法中，接着将getSystemContext设置为刚创建的ActivityThread，并设置AMS中mContext为ActivityThread中的mSystemContext，然后向ServiceManager注册三个service后就调用AMS的startRunning开始AMS的运行：
public final void startRunning(String pkg, String cls, String action,
String data) {
synchronized(this) {
if (mStartRunning) {
return;
}
mStartRunning = true;
mTopComponent = pkg != null && cls != null
? new ComponentName(pkg, cls) : null;
mTopAction = action != null ? action : Intent.ACTION_MAIN;
mTopData = data;
if (!mSystemReady) {
return;
}
}
systemReady(null);
}
因为进入startRunning时mStartRunning和mSystemReady都为false，所以这里只是设置mStartRunning为true，mTopComponent为null，mTopAction为Intent.ACTION_MAIN，mTopData为null就直接返回。到这里AMS的main方法就介绍完了，回到systemServer调用AMS的第二个函数是setSystemProcess：
ActivityManagerService的setSystemProcess方法
public static void setSystemProcess() {
try {
ActivityManagerService m = mSelf;
ServiceManager.addService(Context.ACTIVITY_SERVICE, m, true);
ServiceManager.addService(ProcessStats.SERVICE_NAME, m.mProcessStats);
ServiceManager.addService("meminfo", new MemBinder(m));
ServiceManager.addService("gfxinfo", new GraphicsBinder(m));
ServiceManager.addService("dbinfo", new DbBinder(m));
if (MONITOR_CPU_USAGE) {
ServiceManager.addService("cpuinfo", new CpuBinder(m));
}
ServiceManager.addService("permission", new PermissionController(m));
ApplicationInfo info =
mSelf.mContext.getPackageManager().getApplicationInfo(
"android", STOCK_PM_FLAGS);
mSystemThread.installSystemApplicationInfo(info);
synchronized (mSelf) {
ProcessRecord app = mSelf.newProcessRecordLocked(info,
info.processName, false);
app.persistent = true;
app.pid = MY_PID;
app.maxAdj = ProcessList.SYSTEM_ADJ;
app.makeActive(mSystemThread.getApplicationThread(), mSelf.mProcessStats);
mSelf.mProcessNames.put(app.processName, app.uid, app);
synchronized (mSelf.mPidsSelfLocked) {
mSelf.mPidsSelfLocked.put(app.pid, app);
}
mSelf.updateLruProcessLocked(app, false, null);
mSelf.updateOomAdjLocked();
}
} catch (PackageManager.NameNotFoundException e) {
throw new RuntimeException(
"Unable to find android system package", e);
}
}
这里首先向ServiceManager注册几个服务，然后PMS的getApplicationInfo去获取packageName为"android"的信息，我们知道包名为"android"的APK其实就是"framework-res.apk"，PMS的getApplicationInfo比较简单，都是获取在scanPackageLI保存的mAndroidApplication对象，然后调用mSystemThread的installSystemApplicationInfo将前面获取到的"framework-res.apk"的ApplicantionInfo绑定到mSystemThread的Context上。接着setSystemProcess调用newProcessRecordLocked方法创建一个ProcessRecord对象，ProcessRecord描述一个进程的信息，这里代表framework-res.apk所在的进程信息（也就是systemServer的进程）：
final ProcessRecord newProcessRecordLocked(ApplicationInfo info, String customProcess,
boolean isolated) {
String proc = customProcess != null ? customProcess : info.processName;
BatteryStatsImpl.Uid.Proc ps = null;
BatteryStatsImpl stats = mBatteryStatsService.getActiveStatistics();
int uid = info.uid;
return new ProcessRecord(stats, info, proc, uid);
}
ProcessRecord(BatteryStatsImpl _batteryStats, ApplicationInfo _info,
String _processName, int _uid) {
mBatteryStats = _batteryStats;
info = _info;
isolated = _info.uid != _uid;
uid = _uid;
userId = UserHandle.getUserId(_uid);
processName = _processName;
pkgList.put(_info.packageName, null);
maxAdj = ProcessList.UNKNOWN_ADJ;
curRawAdj = setRawAdj = -100;
curAdj = setAdj = -100;
persistent = false;
removed = false;
lastStateTime = lastPssTime = nextPssTime = SystemClock.uptimeMillis();
}
ProcessRecord记录了当前ApplicationInfo的uid号、processName、以及进程优先级等，并且在pkgList保存了所有在当前进程中的package信息。回到setSystemProcess中将刚创建的ProcessRecord设置为常驻内存，pid号设置为systemServer的进程号。app.makeActive方法用于调用ProcessStatsService开始记录process的状态：
public void makeActive(IApplicationThread _thread, ProcessStatsService tracker) {
if (thread == null) {
final ProcessStats.ProcessState origBase = baseProcessTracker;
if (origBase != null) {
}
baseProcessTracker = tracker.getProcessStateLocked(info.packageName, info.uid,
processName);
baseProcessTracker.makeActive();
for (int i=0; i<pkgList.size(); i++) {
ProcessStats.ProcessState ps = pkgList.valueAt(i);
if (ps != null && ps != origBase) {
ps.makeInactive();
}
ps = tracker.getProcessStateLocked(pkgList.keyAt(i), info.uid, processName);
if (ps != baseProcessTracker) {
ps.makeActive();
}
pkgList.setValueAt(i, ps);
}
}
thread = _thread;
}
makeActive中调用两次getProcessStateLocked去获取ProcessState，其实这两次中的参数完全一样，所以pkgList保持的"system"对应的ProcessState也就是baseProcessTracker。先来看ProcessStatsService的getProcessStateLocked方法：
public ProcessStats.ProcessState getProcessStateLocked(String packageName,
int uid, String processName) {
return mProcessStats.getProcessStateLocked(packageName, uid, processName);
}
public ProcessState getProcessStateLocked(String packageName, int uid, String processName) {
final PackageState pkgState = getPackageStateLocked(packageName, uid);
ProcessState ps = pkgState.mProcesses.get(processName);
if (ps != null) {
return ps;
}
ProcessState commonProc = mProcesses.get(processName, uid);
if (commonProc == null) {
commonProc = new ProcessState(this, packageName, uid, processName);
mProcesses.put(processName, uid, commonProc);
if (DEBUG) Slog.d(TAG, "GETPROC created new common " + commonProc);
}
if (!commonProc.mMultiPackage) {
if (packageName.equals(commonProc.mPackage)) {
ps = commonProc;
if (DEBUG) Slog.d(TAG, "GETPROC also using for pkg " + commonProc);
} else {
}
} else {
}
pkgState.mProcesses.put(processName, ps);
if (DEBUG) Slog.d(TAG, "GETPROC adding new pkg " + ps);
return ps;
}
这里会构造PackageState和ProcessState，并分别添加到mPackages和mProcesses数组中，并将ProcessState添加到PackageState的mProcesses数组中，从这里可以看到，一个Package可以运行在几个process里面，通过一个process也可以运行几个package。下面是上述几个类的结构图：
最后将当前ProcessRecord加入到mProcessNames和mPidsSelfLocked数据结构当中。updateLruProcessLocked用于调整系统优先级，updateOomAdjLocked用于low memory killer，我们将在后面再来介绍。
我们再来看systemServer调用AMS的第三个方法installSystemProviders，这个方法其实就是用来安装SettingsProvider：
ActivityManagerService的installSystemProviders方法
public static final void installSystemProviders() {
List<ProviderInfo> providers;
synchronized (mSelf) {
ProcessRecord app = mSelf.mProcessNames.get("system", Process.SYSTEM_UID);
providers = mSelf.generateApplicationProvidersLocked(app);
if (providers != null) {
for (int i=providers.size()-1; i>=0; i--) {
ProviderInfo pi = (ProviderInfo)providers.get(i);
if ((pi.applicationInfo.flags&ApplicationInfo.FLAG_SYSTEM) == 0) {
Slog.w(TAG, "Not installing system proc provider " + pi.name
+ ": not system .apk");
providers.remove(i);
}
}
}
}
if (providers != null) {
mSystemThread.installSystemProviders(providers);
}
mSelf.mCoreSettingsObserver = new CoreSettingsObserver(mSelf);
mSelf.mUsageStatsService.monitorPackages();
}
这里首先获取前面在setSystemProcess添加到mProcessNames数组当中的ProcessRecord对象，然后调用generateApplicationProvidersLocked从PMS中找到"SettingsProvider.apk"提供的provider，我们可以到SettingsProvider的manifest文件中先看一下这个provider的信息：
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.android.providers.settings"
coreApp="true"
android:sharedUserId="android.uid.system">
<application android:allowClearUserData="false"
android:label="@string/app_label"
android:process="system"
android:backupAgent="SettingsBackupAgent"
android:killAfterRestore="false"
android:icon="@mipmap/ic_launcher_settings">
<!-- todo add: android:neverEncrypt="true" -->
<provider android:name="SettingsProvider" android:authorities="settings"
android:multiprocess="false"
android:exported="true"
android:writePermission="android.permission.WRITE_SETTINGS"
android:initOrder="100" />
</application>
</manifest>
可以看到这个apk的processName也是"system"，并且UID也是"android.uid.system"。再来分析generateApplicationProvidersLocked方法：
private final List<ProviderInfo> generateApplicationProvidersLocked(ProcessRecord app) {
List<ProviderInfo> providers = null;
try {
providers = AppGlobals.getPackageManager().
queryContentProviders(app.processName, app.uid,
STOCK_PM_FLAGS | PackageManager.GET_URI_PERMISSION_PATTERNS);
} catch (RemoteException ex) {
}
int userId = app.userId;
if (providers != null) {
int N = providers.size();
app.pubProviders.ensureCapacity(N + app.pubProviders.size());
for (int i=0; i<N; i++) {
ProviderInfo cpi =
(ProviderInfo)providers.get(i);
ComponentName comp = new ComponentName(cpi.packageName, cpi.name);
ContentProviderRecord cpr = mProviderMap.getProviderByClass(comp, userId);
if (cpr == null) {
cpr = new ContentProviderRecord(this, cpi, app.info, comp, singleton);
mProviderMap.putProviderByClass(comp, cpr);
}
app.pubProviders.put(cpi.name, cpr);
if (!cpi.multiprocess || !"android".equals(cpi.packageName)) {
app.addPackage(cpi.applicationInfo.packageName, mProcessStats);
}
ensurePackageDexOpt(cpi.applicationInfo.packageName);
}
}
return providers;
}
首先调用PMS的queryContentProviders来查询processName和uid与上面相同的provider：
public List<ProviderInfo> queryContentProviders(String processName,
int uid, int flags) {
ArrayList<ProviderInfo> finalList = null;
// reader
synchronized (mPackages) {
final Iterator<PackageParser.Provider> i = mProviders.mProviders.values().iterator();
final int userId = processName != null ?
UserHandle.getUserId(uid) : UserHandle.getCallingUserId();
while (i.hasNext()) {
final PackageParser.Provider p = i.next();
PackageSetting ps = mSettings.mPackages.get(p.owner.packageName);
if (ps != null && p.info.authority != null
&& (processName == null
|| (p.info.processName.equals(processName)
&& UserHandle.isSameApp(p.info.applicationInfo.uid, uid)))
&& mSettings.isEnabledLPr(p.info, flags, userId)
&& (!mSafeMode
|| (p.info.applicationInfo.flags & ApplicationInfo.FLAG_SYSTEM) != 0)) {
if (finalList == null) {
finalList = new ArrayList<ProviderInfo>(3);
}
ProviderInfo info = PackageParser.generateProviderInfo(p, flags,
ps.readUserState(userId), userId);
if (info != null) {
finalList.add(info);
}
}
}
}
if (finalList != null) {
Collections.sort(finalList, mProviderInitOrderSorter);
}
return finalList;
}
queryContentProviders迭代的从mProviders中查找processName为"system"，uid为"SYSTEM_UID"的provider，然后调用generateProviderInfo去copy一份查找的provider信息并添加finalList中。回到前面的generateApplicationProvidersLocked，因为当前provider的processName为"system"，所以singleton为true。接着把查询到的SetttingsProvider添加到AMS的mProviderMap数据结构和ProcessRecord的pubProviders数据结构当中。并把SettingsProvider这个package添加到ProcessRecord的pkgList里，这时ProcessRecord就有两个package在它里面了：
public boolean addPackage(String pkg, ProcessStatsService tracker) {
if (!pkgList.containsKey(pkg)) {
if (baseProcessTracker != null) {
ProcessStats.ProcessState state = tracker.getProcessStateLocked(
pkg, info.uid, processName);
pkgList.put(pkg, state);
if (state != baseProcessTracker) {
state.makeActive();
}
} else {
pkgList.put(pkg, null);
}
return true;
}
return false;
}
先来看一下AMS和ProcessRecord中保存SettingsProvider的数据结构：
我们知道，这里的pkg为"com.android.providers.settings"，通过getProcessStateLocked方法会新建一个ProcessState加入到pkgList中：
public ProcessState getProcessStateLocked(String packageName, int uid, String processName) {
final PackageState pkgState = getPackageStateLocked(packageName, uid);
ProcessState ps = pkgState.mProcesses.get(processName);
if (ps != null) {
return ps;
}
ProcessState commonProc = mProcesses.get(processName, uid);
if (commonProc == null) {
}
if (!commonProc.mMultiPackage) {
if (packageName.equals(commonProc.mPackage)) {
} else {
commonProc.mMultiPackage = true;
long now = SystemClock.uptimeMillis();
final PackageState commonPkgState = getPackageStateLocked(commonProc.mPackage, uid);
if (commonPkgState != null) {
ProcessState cloned = commonProc.clone(commonProc.mPackage, now);
commonPkgState.mProcesses.put(commonProc.mName, cloned);
ps = new ProcessState(commonProc, packageName, uid, processName, now);
if (DEBUG) Slog.d(TAG, "GETPROC created new pkg " + ps);
}
} else {
}
pkgState.mProcesses.put(processName, ps);
if (DEBUG) Slog.d(TAG, "GETPROC adding new pkg " + ps);
return ps;
}
从前面ProcessRecord的makeActive可知，PackageStates中的mPackages数组保存了一个packageName为“android”的PackageState对象PA1，mProcesses保存了一个processName为“system"的ProcessState对象PS1。所以getPackageStateLocked首先还是会创建一个packageName为"com.android.providers.settings"的PackageState对象PA2添加到mPackages数组；然后从mProcesses获取前面processName为“system"的ProcessState对象PS1，此时PS1的pacakgeName与参数中的packageName并不相同，所以这里首先更改commonProc的mMultiPackage为true，然后clone一个ProcessState并替换掉前面保存在PA1的mProcesses数组中PS1。最后再通过PS1创建一个ProcessState并添加刚新创建PA2的mProcesses数组中。注意这里新创建的ProcessState都没有加入到全局的mProcesses数组中，全局mProcesses中还是仅保存PS1。上面的ProcessState的数据结构如下图：
回到AMS的installSystemProviders方法中，接着调用mSystemThread.installSystemProviders，ActivityThread是所有APK运行的主线程，所以这里会构造SettingsProvider对象，并执行它的一些回调函数，让SettingsProvider做好初始化动作：
public final void installSystemProviders(List<ProviderInfo> providers) {
if (providers != null) {
installContentProviders(mInitialApplication, providers);
}
}
private void installContentProviders(
Context context, List<ProviderInfo> providers) {
final ArrayList<IActivityManager.ContentProviderHolder> results =
new ArrayList<IActivityManager.ContentProviderHolder>();
for (ProviderInfo cpi : providers) {
IActivityManager.ContentProviderHolder cph = installProvider(context, null, cpi,
false /*noisy*/, true /*noReleaseNeeded*/, true /*stable*/);
if (cph != null) {
cph.noReleaseNeeded = true;
results.add(cph);
}
}
try {
ActivityManagerNative.getDefault().publishContentProviders(
getApplicationThread(), results);
} catch (RemoteException ex) {
}
}
installContentProviders分为两步，第一步调用installProvider获得一个ContentProviderHolder对象；第二步通过AMS的publishContentProviders方法来完成注册。首先来看installProvider方法：
private IActivityManager.ContentProviderHolder installProvider(Context context,
IActivityManager.ContentProviderHolder holder, ProviderInfo info,
boolean noisy, boolean noReleaseNeeded, boolean stable) {
ContentProvider localProvider = null;
IContentProvider provider;
if (holder == null || holder.provider == null) {
Context c = null;
ApplicationInfo ai = info.applicationInfo;
if (context.getPackageName().equals(ai.packageName)) {
} else if (mInitialApplication != null &&
mInitialApplication.getPackageName().equals(ai.packageName)) {
} else {
try {
c = context.createPackageContext(ai.packageName,
Context.CONTEXT_INCLUDE_CODE);
} catch (PackageManager.NameNotFoundException e) {
// Ignore
}
}
try {
final java.lang.ClassLoader cl = c.getClassLoader();
localProvider = (ContentProvider)cl.
loadClass(info.name).newInstance();
provider = localProvider.getIContentProvider();
localProvider.attachInfo(c, info);
} catch (java.lang.Exception e) {
if (!mInstrumentation.onException(null, e)) {
throw new RuntimeException(
"Unable to get provider " + info.name
+ ": " + e.toString(), e);
}
return null;
}
} else {
}
IActivityManager.ContentProviderHolder retHolder;
synchronized (mProviderMap) {
IBinder jBinder = provider.asBinder();
if (localProvider != null) {
ComponentName cname = new ComponentName(info.packageName, info.name);
ProviderClientRecord pr = mLocalProvidersByName.get(cname);
if (pr != null) {
} else {
holder = new IActivityManager.ContentProviderHolder(info);
holder.provider = provider;
holder.noReleaseNeeded = true;
pr = installProviderAuthoritiesLocked(provider, localProvider, holder);
mLocalProviders.put(jBinder, pr);
mLocalProvidersByName.put(cname, pr);
}
retHolder = pr.mHolder;
} else {
}
}
return retHolder;
}
installProvider方法首先调用ContextImpl的createPackageContext方法去构造SettingsProvider所在的Context环境，在createPackageContext主要是构造一个LoadedApk对象来描述SettingsProvider这个APK，然后通过LoadedApk来初始化一个ContextImpl对象并返回，有兴趣的可以去看一下这部分code。接下来实例化一个SettingsProvider对象，SettingsProvider是继承于ContentProvider的。首先来看一下SettingsProvider的类图结构：
所以localProvider.getIContentProvider获取到一个Transport对象，Transport继承于Binder。接着调用SettingsProvider的attachInfo方法：
public void attachInfo(Context context, ProviderInfo info) {
attachInfo(context, info, false);
}
private void attachInfo(Context context, ProviderInfo info, boolean testing) {
AsyncTask.init();
mNoPerms = testing;
if (mContext == null) {
mContext = context;
if (context != null) {
mTransport.mAppOpsManager = (AppOpsManager) context.getSystemService(
Context.APP_OPS_SERVICE);
}
mMyUid = Process.myUid();
if (info != null) {
setReadPermission(info.readPermission);
setWritePermission(info.writePermission);
setPathPermissions(info.pathPermissions);
mExported = info.exported;
}
ContentProvider.this.onCreate();
}
}
attachInfo主要根据ProviderInfo设置ContentProvider的一些属性以及读写权限，然后回调SettingsProvider的onCreate方法。最后installProvider方法调用installProviderAuthoritiesLocked方法构造一个ProviderClientRecord对象，并添加到mProviderMap、mLocalProviders和mLocalProvidersByName中，这三个ArraryMap可以通过不同键值快速找到对象的ProviderClientRecord对象。最后返回ContentProviderHolder。AcitivytThread中保存SettingsProvider的信息如下：
我们来看第二步通过AMS的publishContentProviders方法来完成注册：
public final void publishContentProviders(IApplicationThread caller,
List<ContentProviderHolder> providers) {
enforceNotIsolatedCaller("publishContentProviders");
synchronized (this) {
final ProcessRecord r = getRecordForAppLocked(caller);
final long origId = Binder.clearCallingIdentity();
final int N = providers.size();
for (int i=0; i<N; i++) {
ContentProviderHolder src = providers.get(i);
if (src == null || src.info == null || src.provider == null) {
continue;
}
ContentProviderRecord dst = r.pubProviders.get(src.info.name);
if (dst != null) {
ComponentName comp = new ComponentName(dst.info.packageName, dst.info.name);
mProviderMap.putProviderByClass(comp, dst);
String names[] = dst.info.authority.split(";");
for (int j = 0; j < names.length; j++) {
mProviderMap.putProviderByName(names[j], dst);
}
int NL = mLaunchingProviders.size();
int j;
for (j=0; j<NL; j++) {
if (mLaunchingProviders.get(j) == dst) {
mLaunchingProviders.remove(j);
j--;
NL--;
}
}
synchronized (dst) {
dst.provider = src.provider;
dst.proc = r;
dst.notifyAll();
}
updateOomAdjLocked(r);
}
}
Binder.restoreCallingIdentity(origId);
}
}
getRecordForAppLocked从mLruProcesses链表中查找并返回我们前面创建的ProcessRecord对象，我们知道在generateApplicationProvidersLocked方法中，我们将从PMS得到的SettingsProvider信息已经添加到ProcessRecord的pubProviders数组中了，这里将provider信息添加到mProviderMap中，并从mLaunchingProviders（表示待启动的provider列表）中移除已经启动的provider。最后回到installSystemProviders方法中，注册一个ContentObserver来监听Settings.Secure.LONG_PRESS_TIMEOUT的变化并调用UsageStatsService去监听package的使用状态。到这里SystemServer调用AMS的installSystemProviders就介绍完了，第四个方法setWindowManager我们先不介绍，等到介绍WMS的时候再来看。最后来看SystemServer调用systemReady方法：
ActivityManagerService的systemReady方法
public void systemReady(final Runnable goingCallback) {
synchronized(this) {
// Check to see if there are any update receivers to run.
if (!mDidUpdate) {
if (mWaitingUpdate) {
return;
}
Intent intent = new Intent(Intent.ACTION_PRE_BOOT_COMPLETED);
List<ResolveInfo> ris = null;
try {
ris = AppGlobals.getPackageManager().queryIntentReceivers(
intent, null, 0, 0);
} catch (RemoteException e) {
}
if (ris != null) {
for (int i=ris.size()-1; i>=0; i--) {
if ((ris.get(i).activityInfo.applicationInfo.flags
&ApplicationInfo.FLAG_SYSTEM) == 0) {
ris.remove(i);
}
}
intent.addFlags(Intent.FLAG_RECEIVER_BOOT_UPGRADE);
ArrayList<ComponentName> lastDoneReceivers = readLastDonePreBootReceivers();
final ArrayList<ComponentName> doneReceivers = new ArrayList<ComponentName>();
for (int i=0; i<ris.size(); i++) {
ActivityInfo ai = ris.get(i).activityInfo;
ComponentName comp = new ComponentName(ai.packageName, ai.name);
if (lastDoneReceivers.contains(comp)) {
ris.remove(i);
i--;
}
}
final int[] users = getUsersLocked();
for (int i=0; i<ris.size(); i++) {
ActivityInfo ai = ris.get(i).activityInfo;
ComponentName comp = new ComponentName(ai.packageName, ai.name);
doneReceivers.add(comp);
intent.setComponent(comp);
for (int j=0; j<users.length; j++) {
IIntentReceiver finisher = null;
if (i == ris.size()-1 && j == users.length-1) {
finisher = new IIntentReceiver.Stub() {
public void performReceive(Intent intent, int resultCode,
String data, Bundle extras, boolean ordered,
boolean sticky, int sendingUser) {
mHandler.post(new Runnable() {
public void run() {
synchronized (ActivityManagerService.this) {
mDidUpdate = true;
}
writeLastDonePreBootReceivers(doneReceivers);
showBootMessage(mContext.getText(
R.string.android_upgrading_complete),
false);
systemReady(goingCallback);
}
});
}
};
}
Slog.i(TAG, "Sending system update to " + intent.getComponent()
+ " for user " + users[j]);
broadcastIntentLocked(null, null, intent, null, finisher,
0, null, null, null, AppOpsManager.OP_NONE,
true, false, MY_PID, Process.SYSTEM_UID,
users[j]);
if (finisher != null) {
mWaitingUpdate = true;
}
}
}
}
if (mWaitingUpdate) {
return;
}
mDidUpdate = true;
}
这是systemReady最开始的一段code，主要用来处理OTA升级后database有改变的状况，这里会从PMS中获取所有接收ACTION_PRE_BOOT_COMPLETED的Receivers，并发送广播给它们，最后会记录这些已经发送广播的Receivers到/data/system/called_pre_boots.dat文件中。关于OTA升级这部分我们先不关注了，接着来看systemReady后面的代码：
ArrayList<ProcessRecord> procsToKill = null;
synchronized(mPidsSelfLocked) {
for (int i=mPidsSelfLocked.size()-1; i>=0; i--) {
ProcessRecord proc = mPidsSelfLocked.valueAt(i);
if (!isAllowedWhileBooting(proc.info)){
if (procsToKill == null) {
procsToKill = new ArrayList<ProcessRecord>();
}
procsToKill.add(proc);
}
}
}
synchronized(this) {
if (procsToKill != null) {
for (int i=procsToKill.size()-1; i>=0; i--) {
ProcessRecord proc = procsToKill.get(i);
Slog.i(TAG, "Removing system update proc: " + proc);
removeProcessLocked(proc, true, false, "system update done");
}
}
mProcessesReady = true;
}
上面的代码主要是杀死在AMS systemReady之前启动的启动process，且这些process没有设置FLAG_PERSISTENT（例如update进程），然后调用removeProcessLocked去结束进程并释放资源，这部分代码我们后面再来介绍。接着来看systemReady函数：
Slog.i(TAG, "System now ready");
synchronized(this) {
if (mFactoryTest == SystemServer.FACTORY_TEST_LOW_LEVEL) {
}
}
retrieveSettings();
synchronized (this) {
readGrantedUriPermissionsLocked();
}
if (goingCallback != null) goingCallback.run();
synchronized (this) {
if (mFactoryTest != SystemServer.FACTORY_TEST_LOW_LEVEL) {
try {
List apps = AppGlobals.getPackageManager().
getPersistentApplications(STOCK_PM_FLAGS);
if (apps != null) {
int N = apps.size();
int i;
for (i=0; i<N; i++) {
ApplicationInfo info
= (ApplicationInfo)apps.get(i);
if (info != null &&
!info.packageName.equals("android")) {
addAppLocked(info, false);
}
}
}
} catch (RemoteException ex) {
// pm is in same process, this will never happen.
}
}
retrieveSettings从SettingsProvider中获取DEBUG_APP、WAIT_FOR_DEBUGGER、ALWAYS_FINISH_ACTIVITIES和DEVELOPMENT_FORCE_RTL四个配置项。readGrantedUriPermissionsLocked从/data/system/urigrants.xml中读取Uri权限，并构造UriPermission保存在AMS全局的mGrantedUriPermissions中，这部分我们以后遇到的时候再来介绍。goingCallback主要调用AMS的startObservingNativeCrashes去建立socket监听底层的NativeCrash消息，并把crash消息传递给AMS的handleApplicationCrashInner函数处理。接着从PMS中获取系统persistent的Application，并调用addAppLocked方法去启动这些Application，关于addAppLocked方法我们后面介绍启动Activity的时候再来介绍。来看systemReady最后一部分的代码：
// Start up initial activity.
mBooting = true;
long ident = Binder.clearCallingIdentity();
try {
Intent intent = new Intent(Intent.ACTION_USER_STARTED);
intent.addFlags(Intent.FLAG_RECEIVER_REGISTERED_ONLY
| Intent.FLAG_RECEIVER_FOREGROUND);
intent.putExtra(Intent.EXTRA_USER_HANDLE, mCurrentUserId);
broadcastIntentLocked(null, null, intent,
null, null, 0, null, null, null, AppOpsManager.OP_NONE,
false, false, MY_PID, Process.SYSTEM_UID, mCurrentUserId);
intent = new Intent(Intent.ACTION_USER_STARTING);
intent.addFlags(Intent.FLAG_RECEIVER_REGISTERED_ONLY);
intent.putExtra(Intent.EXTRA_USER_HANDLE, mCurrentUserId);
broadcastIntentLocked(null, null, intent,
null, new IIntentReceiver.Stub() {
@Override
public void performReceive(Intent intent, int resultCode, String data,
Bundle extras, boolean ordered, boolean sticky, int sendingUser)
throws RemoteException {
}
}, 0, null, null,
android.Manifest.permission.INTERACT_ACROSS_USERS, AppOpsManager.OP_NONE,
true, false, MY_PID, Process.SYSTEM_UID, UserHandle.USER_ALL);
} finally {
Binder.restoreCallingIdentity(ident);
}
mStackSupervisor.resumeTopActivitiesLocked();
sendUserSwitchBroadcastsLocked(-1, mCurrentUserId);
}
}
首先广播ACTION_USER_STARTED和ACTION_USER_STARTING两个消息表示user状态的改变。最后调用mStackSupervisor.resumeTopActivitiesLocked来启动HOME界面：
ActivityMangerService启动HOME
boolean resumeTopActivitiesLocked() {
return resumeTopActivitiesLocked(null, null, null);
}
boolean resumeTopActivitiesLocked(ActivityStack targetStack, ActivityRecord target,
Bundle targetOptions) {
if (targetStack == null) {
targetStack = getFocusedStack();
}
boolean result = false;
for (int stackNdx = mStacks.size() - 1; stackNdx >= 0; --stackNdx) {
final ActivityStack stack = mStacks.get(stackNdx);
if (isFrontStack(stack)) {
if (stack == targetStack) {
result = stack.resumeTopActivityLocked(target, targetOptions);
} else {
stack.resumeTopActivityLocked(null);
}
}
}
return result;
}
ActivityStack getFocusedStack() {
if (mFocusedStack == null) {
return mHomeStack;
}
switch (mStackState) {
case STACK_STATE_HOME_IN_FRONT:
case STACK_STATE_HOME_TO_FRONT:
return mHomeStack;
case STACK_STATE_HOME_IN_BACK:
case STACK_STATE_HOME_TO_BACK:
default:
return mFocusedStack;
}
}
这里主要调用mHomeStack的resumeTopActivityLocked方法来启动HOME界面，mHomeStack是在setWindowManager中构造的，如下：
void setWindowManager(WindowManagerService wm) {
mWindowManager = wm;
mHomeStack = new ActivityStack(mService, mContext, mLooper, HOME_STACK_ID);
mStacks.add(mHomeStack);
}
来看ActivityStack的resumeTopActivityLocked函数：
final boolean resumeTopActivityLocked(ActivityRecord prev, Bundle options) {
ActivityRecord next = topRunningActivityLocked(null);
final boolean userLeaving = mStackSupervisor.mUserLeaving;
mStackSupervisor.mUserLeaving = false;
if (next == null) {
// There are no more activities! Let's just start up the
// Launcher...
ActivityOptions.abort(options);
if (DEBUG_STATES) Slog.d(TAG, "resumeTopActivityLocked: No more activities go home");
if (DEBUG_STACK) mStackSupervisor.validateTopActivitiesLocked();
return mStackSupervisor.resumeHomeActivity(prev);
}
因为当前ActivityStack(HomeStack)中的mTaskHistory为空，所以这里会调用StackSupervisor的resumeHomeActivity方法：
boolean resumeHomeActivity(ActivityRecord prev) {
moveHomeToTop();
if (prev != null) {
prev.task.mOnTopOfHome = false;
}
ActivityRecord r = mHomeStack.topRunningActivityLocked(null);
if (r != null && r.isHomeActivity()) {
}
return mService.startHomeActivityLocked(mCurrentUser);
}
boolean startHomeActivityLocked(int userId) {
Intent intent = getHomeIntent();
ActivityInfo aInfo =
resolveActivityInfo(intent, STOCK_PM_FLAGS, userId);
if (aInfo != null) {
intent.setComponent(new ComponentName(
aInfo.applicationInfo.packageName, aInfo.name));
aInfo = new ActivityInfo(aInfo);
aInfo.applicationInfo = getAppInfoForUser(aInfo.applicationInfo, userId);
ProcessRecord app = getProcessRecordLocked(aInfo.processName,
aInfo.applicationInfo.uid, true);
if (app == null || app.instrumentationClass == null) {
intent.setFlags(intent.getFlags() | Intent.FLAG_ACTIVITY_NEW_TASK);
mStackSupervisor.startHomeActivity(intent, aInfo);
}
}
return true;
}
最终调用到AMS的startHomeActivityLocked，这里首先调用getHomeIntent构造一个Action为ACTION_MAIN，Category为CATEGORY_HOME的Intent，然后通过查找PMS中接收的所有ActivityInfo：
private ActivityInfo resolveActivityInfo(Intent intent, int flags, int userId) {
ActivityInfo ai = null;
ComponentName comp = intent.getComponent();
try {
if (comp != null) {
} else {
ResolveInfo info = AppGlobals.getPackageManager().resolveIntent(
intent,
intent.resolveTypeIfNeeded(mContext.getContentResolver()),
flags, userId);
if (info != null) {
ai = info.activityInfo;
}
}
} catch (RemoteException e) {
// ignore
}
return ai;
}
public ResolveInfo resolveIntent(Intent intent, String resolvedType,
int flags, int userId) {
if (!sUserManager.exists(userId)) return null;
enforceCrossUserPermission(Binder.getCallingUid(), userId, false, "resolve intent");
List<ResolveInfo> query = queryIntentActivities(intent, resolvedType, flags, userId);
return chooseBestActivity(intent, resolvedType, flags, query, userId);
}
关于queryIntentActivities和chooseBestActivity我们以后再来分析，这里假设系统只有一个launcher，它的manifest文件如下：
<application
android:name="com.android.launcher2.LauncherApplication"
android:label="@string/application_name"
android:icon="@mipmap/ic_launcher_home"
android:hardwareAccelerated="true"
android:largeHeap="@bool/config_largeHeap"
android:supportsRtl="true">
<activity
android:name="com.android.launcher2.Launcher"
android:launchMode="singleTask"
android:clearTaskOnLaunch="true"
android:stateNotNeeded="true"
android:theme="@style/Theme"
android:windowSoftInputMode="adjustPan"
android:screenOrientation="nosensor">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.HOME" />
<category android:name="android.intent.category.DEFAULT" />
<category android:name="android.intent.category.MONKEY"/>
</intent-filter>
</activity>
在startHomeActivityLocked因为没有存在Launcher的ProcessRecord信息，所以调用mStackSupervisor.startHomeActivity去启动launcher，并且设置了FLAG_ACTIVITY_NEW_TASK，表示新建一个task来运行launcher：
void startHomeActivity(Intent intent, ActivityInfo aInfo) {
moveHomeToTop();
startActivityLocked(null, intent, null, aInfo, null, null, 0, 0, 0, null, 0,
null, false, null);
}
final int startActivityLocked(IApplicationThread caller,
Intent intent, String resolvedType, ActivityInfo aInfo, IBinder resultTo,
String resultWho, int requestCode,
int callingPid, int callingUid, String callingPackage, int startFlags, Bundle options,
boolean componentSpecified, ActivityRecord[] outActivity) {
int err = ActivityManager.START_SUCCESS;
ProcessRecord callerApp = null;
if (caller != null) {
}
if (err == ActivityManager.START_SUCCESS) {
final int userId = aInfo != null ? UserHandle.getUserId(aInfo.applicationInfo.uid) : 0;
Slog.i(TAG, "START u" + userId + " {" + intent.toShortString(true, true, true, false)
+ "} from pid " + (callerApp != null ? callerApp.pid : callingPid));
}
ActivityRecord sourceRecord = null;
ActivityRecord resultRecord = null;
if (resultTo != null) {
}
ActivityStack resultStack = resultRecord == null ? null : resultRecord.task.stack;
int launchFlags = intent.getFlags();
if ((launchFlags&Intent.FLAG_ACTIVITY_FORWARD_RESULT) != 0
&& sourceRecord != null) {
}
if (err == ActivityManager.START_SUCCESS && intent.getComponent() == null) {
}
if (err == ActivityManager.START_SUCCESS && aInfo == null) {
}
if (err != ActivityManager.START_SUCCESS) {
}
final int startAnyPerm = mService.checkPermission(
START_ANY_ACTIVITY, callingPid, callingUid);
final int componentPerm = mService.checkComponentPermission(aInfo.permission, callingPid,
callingUid, aInfo.applicationInfo.uid, aInfo.exported);
if (startAnyPerm != PERMISSION_GRANTED && componentPerm != PERMISSION_GRANTED) {
}
boolean abort = !mService.mIntentFirewall.checkStartActivity(intent, callingUid,
callingPid, resolvedType, aInfo.applicationInfo);
if (mService.mController != null) {
}
if (abort) {
}
ActivityRecord r = new ActivityRecord(mService, callerApp, callingUid, callingPackage,
intent, resolvedType, aInfo, mService.mConfiguration,
resultRecord, _resultWho, requestCode, componentSpecified, this);
if (outActivity != null) {
outActivity[0] = r;
}
final ActivityStack stack = getFocusedStack();
if (stack.mResumedActivity == null
|| stack.mResumedActivity.info.applicationInfo.uid != callingUid) {
if (!mService.checkAppSwitchAllowedLocked(callingPid, callingUid, "Activity start")) {
}
}
if (mService.mDidAppSwitch) {
mService.mAppSwitchesAllowedTime = 0;
} else {
mService.mDidAppSwitch = true;
}
mService.doPendingActivityLaunchesLocked(false);
err = startActivityUncheckedLocked(r, sourceRecord, startFlags, true, options);
if (allPausedActivitiesComplete()) {
dismissKeyguard();
}
return err;
}
在startActivityLocked中首先做一些权限的检查，然后构造一个ActivityRecord对象，一个ActivityRecord就表示一个Activity实体，先来看一下构造ActivityRecord的参数：_service就是AMS本身，_caller为NULL，_launchedFromUid为0，_launchedFromPackage为NULL，_intent为启动Activity的Intent，_resolvedType为NULL，aInfo为从PMS获取到的ActivityInfo，_configuration为AMS的mConfiguration，_resultTo为NULL，_resultWho为NULl，_reqCode为0，_componentSpecified为false，supervisor为ActivityStackSupervisor本身：
ActivityRecord(ActivityManagerService _service, ProcessRecord _caller,
int _launchedFromUid, String _launchedFromPackage, Intent _intent, String _resolvedType,
ActivityInfo aInfo, Configuration _configuration,
ActivityRecord _resultTo, String _resultWho, int _reqCode,
boolean _componentSpecified, ActivityStackSupervisor supervisor) {
service = _service;
appToken = new Token(this);
info = aInfo;
launchedFromUid = _launchedFromUid;
launchedFromPackage = _launchedFromPackage;
userId = UserHandle.getUserId(aInfo.applicationInfo.uid);
intent = _intent;
shortComponentName = _intent.getComponent().flattenToShortString();
resolvedType = _resolvedType;
componentSpecified = _componentSpecified;
configuration = _configuration;
resultTo = _resultTo;
resultWho = _resultWho;
requestCode = _reqCode;
state = ActivityState.INITIALIZING;
frontOfTask = false;
launchFailed = false;
stopped = false;
delayedResume = false;
finishing = false;
configDestroy = false;
keysPaused = false;
inHistory = false;
visible = true;
waitingVisible = false;
nowVisible = false;
thumbnailNeeded = false;
idle = false;
hasBeenLaunched = false;
mStackSupervisor = supervisor;
// This starts out true, since the initial state of an activity
// is that we have everything, and we shouldn't never consider it
// lacking in state to be removed if it dies.
haveState = true;
if (aInfo != null) {
if (aInfo.targetActivity == null
|| aInfo.launchMode == ActivityInfo.LAUNCH_MULTIPLE
|| aInfo.launchMode == ActivityInfo.LAUNCH_SINGLE_TOP) {
realActivity = _intent.getComponent();
} else {
realActivity = new ComponentName(aInfo.packageName,
aInfo.targetActivity);
}
taskAffinity = aInfo.taskAffinity;
stateNotNeeded = (aInfo.flags&
ActivityInfo.FLAG_STATE_NOT_NEEDED) != 0;
baseDir = aInfo.applicationInfo.sourceDir;
resDir = aInfo.applicationInfo.publicSourceDir;
dataDir = aInfo.applicationInfo.dataDir;
nonLocalizedLabel = aInfo.nonLocalizedLabel;
labelRes = aInfo.labelRes;
if (nonLocalizedLabel == null && labelRes == 0) {
ApplicationInfo app = aInfo.applicationInfo;
nonLocalizedLabel = app.nonLocalizedLabel;
labelRes = app.labelRes;
}
icon = aInfo.getIconResource();
logo = aInfo.getLogoResource();
theme = aInfo.getThemeResource();
realTheme = theme;
if (realTheme == 0) {
realTheme = aInfo.applicationInfo.targetSdkVersion
< Build.VERSION_CODES.HONEYCOMB
? android.R.style.Theme
: android.R.style.Theme_Holo;
}
if ((aInfo.flags&ActivityInfo.FLAG_HARDWARE_ACCELERATED) != 0) {
windowFlags |= WindowManager.LayoutParams.FLAG_HARDWARE_ACCELERATED;
}
if ((aInfo.flags&ActivityInfo.FLAG_MULTIPROCESS) != 0
&& _caller != null
&& (aInfo.applicationInfo.uid == Process.SYSTEM_UID
|| aInfo.applicationInfo.uid == _caller.info.uid)) {
processName = _caller.processName;
} else {
processName = aInfo.processName;
}
if (intent != null && (aInfo.flags & ActivityInfo.FLAG_EXCLUDE_FROM_RECENTS) != 0) {
intent.addFlags(Intent.FLAG_ACTIVITY_EXCLUDE_FROM_RECENTS);
}
packageName = aInfo.applicationInfo.packageName;
launchMode = aInfo.launchMode;
AttributeCache.Entry ent = AttributeCache.instance().get(packageName,
realTheme, com.android.internal.R.styleable.Window, userId);
fullscreen = ent != null && !ent.array.getBoolean(
com.android.internal.R.styleable.Window_windowIsFloating, false)
&& !ent.array.getBoolean(
com.android.internal.R.styleable.Window_windowIsTranslucent, false);
noDisplay = ent != null && ent.array.getBoolean(
com.android.internal.R.styleable.Window_windowNoDisplay, false);
if ((!_componentSpecified || _launchedFromUid == Process.myUid()
|| _launchedFromUid == 0) &&
Intent.ACTION_MAIN.equals(_intent.getAction()) &&
_intent.hasCategory(Intent.CATEGORY_HOME) &&
_intent.getCategories().size() == 1 &&
_intent.getData() == null &&
_intent.getType() == null &&
(intent.getFlags()&Intent.FLAG_ACTIVITY_NEW_TASK) != 0 &&
isNotResolverActivity()) {
// This sure looks like a home activity!
mActivityType = HOME_ACTIVITY_TYPE;
} else if (realActivity.getClassName().contains(RECENTS_PACKAGE_NAME)) {
mActivityType = RECENTS_ACTIVITY_TYPE;
} else {
mActivityType = APPLICATION_ACTIVITY_TYPE;
}
immersive = (aInfo.flags & ActivityInfo.FLAG_IMMERSIVE) != 0;
}
在ActivityRecord主要是通过ActivityInfo去设置自身的一些成员变量。然后startActivityLocked调用AMS的doPendingActivityLaunchesLocked去处理mPendingActivityLaunches中被pending中的启动Activity请求，最后调用startActivityUncheckedLocked去启动launcher这个Activity：
final int startActivityUncheckedLocked(ActivityRecord r,
ActivityRecord sourceRecord, int startFlags, boolean doResume,
Bundle options) {
final Intent intent = r.intent;
final int callingUid = r.launchedFromUid;
int launchFlags = intent.getFlags();
if (!doResume) {
}
ActivityRecord notTop = (launchFlags&Intent.FLAG_ACTIVITY_PREVIOUS_IS_TOP) != 0 ? r : null;
if ((startFlags&ActivityManager.START_FLAG_ONLY_IF_NEEDED) != 0) {
}
if (sourceRecord == null) {
if ((launchFlags&Intent.FLAG_ACTIVITY_NEW_TASK) == 0) {
launchFlags |= Intent.FLAG_ACTIVITY_NEW_TASK;
}
} else if (sourceRecord.launchMode == ActivityInfo.LAUNCH_SINGLE_INSTANCE) {
} else if (r.launchMode == ActivityInfo.LAUNCH_SINGLE_INSTANCE
|| r.launchMode == ActivityInfo.LAUNCH_SINGLE_TASK) {
}
ActivityInfo newTaskInfo = null;
Intent newTaskIntent = null;
final ActivityStack sourceStack;
if (sourceRecord != null) {
} else {
sourceStack = null;
}
if (r.resultTo != null && (launchFlags&Intent.FLAG_ACTIVITY_NEW_TASK) != 0) {
}
boolean addingToTask = false;
boolean movedHome = false;
TaskRecord reuseTask = null;
ActivityStack targetStack;
if (((launchFlags&Intent.FLAG_ACTIVITY_NEW_TASK) != 0 &&
(launchFlags&Intent.FLAG_ACTIVITY_MULTIPLE_TASK) == 0)
|| r.launchMode == ActivityInfo.LAUNCH_SINGLE_TASK
|| r.launchMode == ActivityInfo.LAUNCH_SINGLE_INSTANCE) {
if (r.resultTo == null) {
//找到与此Activity相同亲属关系的ActivityRecord
ActivityRecord intentActivity = r.launchMode != ActivityInfo.LAUNCH_SINGLE_INSTANCE
? findTaskLocked(r)
: findActivityLocked(intent, r.info);
if (intentActivity != null) {
}
}
}
if (r.packageName != null) {
ActivityStack topStack = getFocusedStack();
ActivityRecord top = topStack.topRunningNonDelayedActivityLocked(notTop);
//待启动Activity所属的ActivityStack为当前focus的ActivityStack
if (top != null && r.resultTo == null) {
if (top.realActivity.equals(r.realActivity) && top.userId == r.userId) {
}
}
} else {
}
boolean newTask = false;
boolean keepCurTransition = false;
if (r.resultTo == null && !addingToTask
&& (launchFlags&Intent.FLAG_ACTIVITY_NEW_TASK) != 0) {
targetStack = adjustStackFocus(r);
moveHomeStack(targetStack.isHomeStack());
if (reuseTask == null) {
r.setTask(targetStack.createTaskRecord(getNextTaskId(),
newTaskInfo != null ? newTaskInfo : r.info,
newTaskIntent != null ? newTaskIntent : intent,
true), null, true);
if (DEBUG_TASKS) Slog.v(TAG, "Starting new activity " + r + " in new task " +
r.task);
} else {
}
newTask = true;
if (!movedHome) {
if ((launchFlags &
(Intent.FLAG_ACTIVITY_NEW_TASK|Intent.FLAG_ACTIVITY_TASK_ON_HOME))
== (Intent.FLAG_ACTIVITY_NEW_TASK|Intent.FLAG_ACTIVITY_TASK_ON_HOME)) {
}
}
} else if (sourceRecord != null) {
} else {
}
targetStack.mLastPausedActivity = null;
targetStack.startActivityLocked(r, newTask, doResume, keepCurTransition, options);
mService.setFocusedActivityLocked(r);
return ActivityManager.START_SUCCESS;
}
startActivityUncheckedLocked根据系统的状态、Intent设置的flag以及待启动Activity的属性等分为很多种case，我们先只关注启动launcher的流程。这里的targetStack就是mHomeStack，调用它的createTaskRecord方法创建一个新的TaskRecord对象并设置给新的ActivityRecord，一个TaskRecord对象表示一个新的任务，一个任务由一组Activity来共同组成。先来看创建TaskRecord的代码：
TaskRecord createTaskRecord(int taskId, ActivityInfo info, Intent intent, boolean toTop) {
TaskRecord task = new TaskRecord(taskId, info, intent);
addTask(task, toTop);
return task;
}
TaskRecord(int _taskId, ActivityInfo info, Intent _intent) {
taskId = _taskId;
affinity = info.taskAffinity;
setIntent(_intent, info);
}
void setIntent(Intent _intent, ActivityInfo info) {
stringName = null;
if (info.targetActivity == null) {
} else {
ComponentName targetComponent = new ComponentName(
info.packageName, info.targetActivity);
if (_intent != null) {
Intent targetIntent = new Intent(_intent);
targetIntent.setComponent(targetComponent);
targetIntent.setSelector(null);
targetIntent.setSourceBounds(null);
if (ActivityManagerService.DEBUG_TASKS) Slog.v(ActivityManagerService.TAG,
"Setting Intent of " + this + " to target " + targetIntent);
intent = targetIntent;
realActivity = targetComponent;
origActivity = _intent.getComponent();
} else {
intent = null;
realActivity = targetComponent;
origActivity = new ComponentName(info.packageName, info.name);
}
}
if (intent != null &&
(intent.getFlags()&Intent.FLAG_ACTIVITY_RESET_TASK_IF_NEEDED) != 0) {
}
if (info.applicationInfo != null) {
userId = UserHandle.getUserId(info.applicationInfo.uid);
}
}
void addTask(final TaskRecord task, final boolean toTop) {
task.stack = this;
if (toTop) {
insertTaskAtTop(task);
} else {
mTaskHistory.add(0, task);
}
}
private void insertTaskAtTop(TaskRecord task) {
ActivityStack lastStack = mStackSupervisor.getLastStack();
final boolean fromHome = lastStack == null ? true : lastStack.isHomeStack();
if (!isHomeStack() && (fromHome || topTask() != task)) {
task.mOnTopOfHome = fromHome;
}
mTaskHistory.remove(task);
int stackNdx = mTaskHistory.size();
if (task.userId != mCurrentUser) {
// Put non-current user tasks below current user tasks.
while (--stackNdx >= 0) {
if (mTaskHistory.get(stackNdx).userId != mCurrentUser) {
break;
}
}
++stackNdx;
}
mTaskHistory.add(stackNdx, task);
}
上面的代码都比较简单，首先构造TaskRecord，并把它添加到mTaskHistory数组中。接下来调用ActivityRecord的setTask把待启动的Activity绑定到此TaskRecord上：
void setTask(TaskRecord newTask, ThumbnailHolder newThumbHolder, boolean isRoot) {
if (task != null && task.removeActivity(this)) {
}
if (inHistory && !finishing) {
}
if (newThumbHolder == null) {
newThumbHolder = newTask;
}
task = newTask;
if (!isRoot && (intent.getFlags()&Intent.FLAG_ACTIVITY_CLEAR_WHEN_TASK_RESET) != 0) {
} else {
thumbHolder = newThumbHolder;
}
}
接下来在startActivityUncheckedLocked调用ActivityStack的startActivityLocked方法来启动这个Activity：
final void startActivityLocked(ActivityRecord r, boolean newTask,
boolean doResume, boolean keepCurTransition, Bundle options) {
TaskRecord rTask = r.task;
final int taskId = rTask.taskId;
if (taskForIdLocked(taskId) == null || newTask) {
}
TaskRecord task = null;
if (!newTask) {
}
if (task == r.task && mTaskHistory.indexOf(task) != (mTaskHistory.size() - 1)) {
}
task = r.task;
task.addActivityToTop(r);
r.putInHistory();
r.frontOfTask = newTask;
if (!isHomeStack() || numActivities() > 0) {
boolean showStartingIcon = newTask;
ProcessRecord proc = r.app;
if (proc == null) {
proc = mService.mProcessNames.get(r.processName, r.info.applicationInfo.uid);
}
if (proc == null || proc.thread == null) {
showStartingIcon = true;
}
if ((r.intent.getFlags()&Intent.FLAG_ACTIVITY_NO_ANIMATION) != 0) {
} else {
mWindowManager.prepareAppTransition(newTask
? AppTransition.TRANSIT_TASK_OPEN
: AppTransition.TRANSIT_ACTIVITY_OPEN, keepCurTransition);
mNoAnimActivities.remove(r);
}
r.updateOptionsLocked(options);
mWindowManager.addAppToken(task.mActivities.indexOf(r),
r.appToken, r.task.taskId, mStackId, r.info.screenOrientation, r.fullscreen,
(r.info.flags & ActivityInfo.FLAG_SHOW_ON_LOCK_SCREEN) != 0, r.userId,
r.info.configChanges);
boolean doShow = true;
if (newTask) {
if ((r.intent.getFlags()
&Intent.FLAG_ACTIVITY_RESET_TASK_IF_NEEDED) != 0) {
}
}
if (SHOW_APP_STARTING_PREVIEW && doShow) {
ActivityRecord prev = mResumedActivity;
if (prev != null) {
}
mWindowManager.setAppStartingWindow(
r.appToken, r.packageName, r.theme,
mService.compatibilityInfoForPackageLocked(
r.info.applicationInfo), r.nonLocalizedLabel,
r.labelRes, r.icon, r.logo, r.windowFlags,
prev != null ? prev.appToken : null, showStartingIcon);
}
} else {
}
if (VALIDATE_TOKENS) {
validateAppTokensLocked();
}
if (doResume) {
mStackSupervisor.resumeTopActivitiesLocked();
}
}
在ActivityStack的startActivityLocked方法中，首先把新的ActivityRecord添加到TaskRecord的mActivities数组中，表示当前task包含此Activity。接下来调用WMS的prepareAppTransition、addAppToken和setAppStartingWindow接口为Activity的切换做准备，关于WMS的内容，我们后面再来介绍。最后调用mStackSupervisor.resumeTopActivitiesLocked去启动Activity：
boolean resumeTopActivitiesLocked() {
return resumeTopActivitiesLocked(null, null, null);
}
boolean resumeTopActivitiesLocked(ActivityStack targetStack, ActivityRecord target,
Bundle targetOptions) {
if (targetStack == null) {
targetStack = getFocusedStack();
}
boolean result = false;
for (int stackNdx = mStacks.size() - 1; stackNdx >= 0; --stackNdx) {
final ActivityStack stack = mStacks.get(stackNdx);
if (isFrontStack(stack)) {
if (stack == targetStack) {
result = stack.resumeTopActivityLocked(target, targetOptions);
} else {
stack.resumeTopActivityLocked(null);
}
}
}
return result;
}
这里会再次调用到ActivityStack的resumeTopActivityLocked去完成Activity的启动：
final boolean resumeTopActivityLocked(ActivityRecord prev, Bundle options) {
ActivityRecord next = topRunningActivityLocked(null);
final boolean userLeaving = mStackSupervisor.mUserLeaving;
mStackSupervisor.mUserLeaving = false;
if (next == null) {
}
next.delayedResume = false;
if (mResumedActivity == next && next.state == ActivityState.RESUMED &&
mStackSupervisor.allResumedActivitiesComplete()) {
}
final TaskRecord nextTask = next.task;
final TaskRecord prevTask = prev != null ? prev.task : null;
if (prevTask != null && prevTask.mOnTopOfHome && prev.finishing && prev.frontOfTask) {
}
if (mService.isSleepingOrShuttingDown()
&& mLastPausedActivity == next
&& mStackSupervisor.allPausedActivitiesComplete()) {
}
mStackSupervisor.mStoppingActivities.remove(next);
mStackSupervisor.mGoingToSleepActivities.remove(next);
next.sleeping = false;
mStackSupervisor.mWaitingVisibleActivities.remove(next);
next.updateOptionsLocked(options);
if (!mStackSupervisor.allPausedActivitiesComplete()) {
}
boolean pausing = mStackSupervisor.pauseBackStacks(userLeaving);
if (mResumedActivity != null) {
pausing = true;
startPausingLocked(userLeaving, false);
if (DEBUG_STATES) Slog.d(TAG, "resumeTopActivityLocked: Pausing " + mResumedActivity);
}
if (pausing) {
}
if (mService.mSleeping && mLastNoHistoryActivity != null &&
!mLastNoHistoryActivity.finishing) {
}
if (prev != null && prev != next) {
}
// Launching this app's activity, make sure the app is no longer
// considered stopped.
try {
AppGlobals.getPackageManager().setPackageStoppedState(
next.packageName, false, next.userId); /* TODO: Verify if correct userid */
} catch (RemoteException e1) {
} catch (IllegalArgumentException e) {
Slog.w(TAG, "Failed trying to unstop package "
+ next.packageName + ": " + e);
}
boolean anim = true;
if (prev != null) {
} else {
if (mNoAnimActivities.contains(next)) {
anim = false;
mWindowManager.prepareAppTransition(AppTransition.TRANSIT_NONE, false);
} else {
mWindowManager.prepareAppTransition(AppTransition.TRANSIT_ACTIVITY_OPEN, false);
}
}
if (anim) {
next.applyOptionsLocked();
} else {
next.clearOptionsLocked();
}
ActivityStack lastStack = mStackSupervisor.getLastStack();
if (next.app != null && next.app.thread != null) {
} else {
// Whoops, need to restart this activity!
if (!next.hasBeenLaunched) {
next.hasBeenLaunched = true;
} else {
if (SHOW_APP_STARTING_PREVIEW) {
}
if (DEBUG_SWITCH) Slog.v(TAG, "Restarting: " + next);
}
if (DEBUG_STATES) Slog.d(TAG, "resumeTopActivityLocked: Restarting " + next);
mStackSupervisor.startSpecificActivityLocked(next, true, true);
}
if (DEBUG_STACK) mStackSupervisor.validateTopActivitiesLocked();
return true;
}
此时topRunningActivityLocked()中返回launcher所代表的的ActivityRecord对象，并最终调用mStackSupervisor.startSpecificActivityLocked去启动Activity：
void startSpecificActivityLocked(ActivityRecord r,
boolean andResume, boolean checkConfig) {
ProcessRecord app = mService.getProcessRecordLocked(r.processName,
r.info.applicationInfo.uid, true);
r.task.stack.setLaunchTime(r);
if (app != null && app.thread != null) {
}
mService.startProcessLocked(r.processName, r.info.applicationInfo, true, 0,
"activity", r.intent.getComponent(), false, false, true);
}
final ProcessRecord startProcessLocked(String processName,
ApplicationInfo info, boolean knownToBeDead, int intentFlags,
String hostingType, ComponentName hostingName, boolean allowWhileBooting,
boolean isolated, boolean keepIfLarge) {
ProcessRecord app;
if (!isolated) {
app = getProcessRecordLocked(processName, info.uid, keepIfLarge);
} else {
app = null;
}
if (app != null && app.pid > 0) {
}
String hostingNameStr = hostingName != null
? hostingName.flattenToShortString() : null;
if (app == null) {
app = newProcessRecordLocked(info, processName, isolated);
mProcessNames.put(processName, app.uid, app);
}
} else {
}
startProcessLocked(app, hostingType, hostingNameStr);
return (app.pid != 0) ? app : null;
}
因为launcher的Process并没有创建，所以也没有它的ProcessRecord对象存在，这里首先创建一个ProcessRecord对象，并调用startProcessLocked通过Zygote去fork一个进程，并把进程的pid号保存在ProcessRecord.pid里。关于Zygote如何fork一个进程，我们这里先不关注了，fork进程完后，就会执行到ActivityThread的main方法，我们从这里开始分析：
public static void main(String[] args) {
SamplingProfilerIntegration.start();
CloseGuard.setEnabled(false);
Environment.initForCurrentUser();
EventLogger.setReporter(new EventLoggingReporter());
Security.addProvider(new AndroidKeyStoreProvider());
Process.setArgV0("<pre-initialized>");
Looper.prepareMainLooper();
ActivityThread thread = new ActivityThread();
thread.attach(false);
if (sMainThreadHandler == null) {
sMainThreadHandler = thread.getHandler();
}
AsyncTask.init();
Looper.loop();
throw new RuntimeException("Main thread loop unexpectedly exited");
}
这里首先初始化一些环境，然后调用ActivtityThread自身的attach方法，并最终开始looper循环。前面在介绍AMS启动的时候，也会构造ActivityThread对象，但它调用attach方法传入的参数为true，表示为system的进程，我们这里传入的参数为false：
private void attach(boolean system) {
sCurrentActivityThread = this;
mSystemThread = system;
if (!system) {
ViewRootImpl.addFirstDrawHandler(new Runnable() {
@Override
public void run() {
ensureJitEnabled();
}
});
android.ddm.DdmHandleAppName.setAppName("<pre-initialized>",
UserHandle.myUserId());
RuntimeInit.setApplicationObject(mAppThread.asBinder());
IActivityManager mgr = ActivityManagerNative.getDefault();
try {
mgr.attachApplication(mAppThread);
} catch (RemoteException ex) {
// Ignore
}
} else {
}
ViewRootImpl.addConfigCallback(new ComponentCallbacks2() {
@Override
public void onConfigurationChanged(Configuration newConfig) {
synchronized (mResourcesManager) {
// We need to apply this change to the resources
// immediately, because upon returning the view
// hierarchy will be informed about it.
if (mResourcesManager.applyConfigurationToResourcesLocked(newConfig, null)) {
// This actually changed the resources! Tell
// everyone about it.
if (mPendingConfiguration == null ||
mPendingConfiguration.isOtherSeqNewer(newConfig)) {
mPendingConfiguration = newConfig;
sendMessage(H.CONFIGURATION_CHANGED, newConfig);
}
}
}
}
@Override
public void onLowMemory() {
}
@Override
public void onTrimMemory(int level) {
}
});
}
在attach方法中，首先设置进程名字，这个名字只是在启动过程中显示。然后调用AMS的attachApplication方法：
private final boolean attachApplicationLocked(IApplicationThread thread,
int pid) {
ProcessRecord app;
if (pid != MY_PID && pid >= 0) {
synchronized (mPidsSelfLocked) {
app = mPidsSelfLocked.get(pid);
}
} else {
app = null;
}
final String processName = app.processName;
try {
AppDeathRecipient adr = new AppDeathRecipient(
app, pid, thread);
thread.asBinder().linkToDeath(adr, 0);
app.deathRecipient = adr;
} catch (RemoteException e) {
app.resetPackageList(mProcessStats);
startProcessLocked(app, "link fail", processName);
return false;
}
app.makeActive(thread, mProcessStats);
app.curAdj = app.setAdj = -100;
app.curSchedGroup = app.setSchedGroup = Process.THREAD_GROUP_DEFAULT;
app.forcingToForeground = null;
app.foregroundServices = false;
app.hasShownUi = false;
app.debugging = false;
app.cached = false;
mHandler.removeMessages(PROC_START_TIMEOUT_MSG, app);
boolean normalMode = mProcessesReady || isAllowedWhileBooting(app.info);
List<ProviderInfo> providers = normalMode ? generateApplicationProvidersLocked(app) : null;
try {
String profileFile = app.instrumentationProfileFile;
ParcelFileDescriptor profileFd = null;
boolean profileAutoStop = false;
boolean enableOpenGlTrace = false;
boolean isRestrictedBackupMode = false;
ensurePackageDexOpt(app.instrumentationInfo != null
? app.instrumentationInfo.packageName
: app.info.packageName);
ApplicationInfo appInfo = app.instrumentationInfo != null
? app.instrumentationInfo : app.info;
app.compat = compatibilityInfoForPackageLocked(appInfo);
if (profileFd != null) {
profileFd = profileFd.dup();
}
thread.bindApplication(processName, appInfo, providers,
app.instrumentationClass, profileFile, profileFd, profileAutoStop,
app.instrumentationArguments, app.instrumentationWatcher,
app.instrumentationUiAutomationConnection, testMode, enableOpenGlTrace,
isRestrictedBackupMode || !normalMode, app.persistent,
new Configuration(mConfiguration), app.compat, getCommonServicesLocked(),
mCoreSettingsObserver.getCoreSettingsLocked());
updateLruProcessLocked(app, false, null);
app.lastRequestedGc = app.lastLowMemory = SystemClock.uptimeMillis();
} catch (Exception e) {
app.resetPackageList(mProcessStats);
app.unlinkDeathRecipient();
startProcessLocked(app, "bind fail", processName);
return false;
}
mPersistentStartingProcesses.remove(app);
if (DEBUG_PROCESSES && mProcessesOnHold.contains(app)) Slog.v(TAG,
"Attach application locked removing on hold: " + app);
mProcessesOnHold.remove(app);
boolean badApp = false;
boolean didSomething = false;
if (normalMode) {
try {
if (mStackSupervisor.attachApplicationLocked(app, mHeadless)) {
didSomething = true;
}
} catch (Exception e) {
badApp = true;
}
}
if (!badApp) {
try {
didSomething |= mServices.attachApplicationLocked(app, processName);
} catch (Exception e) {
badApp = true;
}
}
if (!badApp && isPendingBroadcastProcessLocked(pid)) {
try {
didSomething |= sendPendingBroadcastsLocked(app);
} catch (Exception e) {
// If the app died trying to launch the receiver we declare it 'bad'
badApp = true;
}
}
if (!didSomething) {
updateOomAdjLocked();
}
return true;
}
attachApplicationLocked函数比较长，首先调用ProcessRecord的makeActive方法调用ProcessStatsService开始记录process的状态。后面主要做了四件事情：一是调用ActivityThread的bindApplication方法去启动Application；二是调用StackSupervisor的attachApplicationLocked去启动ActivityStack栈顶的Activity；三是根据mPendingServices和mRestartingServices列表启动在当前application中的service；四是检查是否有广播broadcast到这个application，如果有则广播。后面两件事我们这里先不讨论，首先来看前面两个方法：
public final void bindApplication(String processName,
ApplicationInfo appInfo, List<ProviderInfo> providers,
ComponentName instrumentationName, String profileFile,
ParcelFileDescriptor profileFd, boolean autoStopProfiler,
Bundle instrumentationArgs, IInstrumentationWatcher instrumentationWatcher,
IUiAutomationConnection instrumentationUiConnection, int debugMode,
boolean enableOpenGlTrace, boolean isRestrictedBackupMode, boolean persistent,
Configuration config, CompatibilityInfo compatInfo, Map<String, IBinder> services,
Bundle coreSettings) {
if (services != null) {
// Setup the service cache in the ServiceManager
ServiceManager.initServiceCache(services);
}
setCoreSettings(coreSettings);
AppBindData data = new AppBindData();
data.processName = processName;
data.appInfo = appInfo;
data.providers = providers;
data.instrumentationName = instrumentationName;
data.instrumentationArgs = instrumentationArgs;
data.instrumentationWatcher = instrumentationWatcher;
data.instrumentationUiAutomationConnection = instrumentationUiConnection;
data.debugMode = debugMode;
data.enableOpenGlTrace = enableOpenGlTrace;
data.restrictedBackupMode = isRestrictedBackupMode;
data.persistent = persistent;
data.config = config;
data.compatInfo = compatInfo;
data.initProfileFile = profileFile;
data.initProfileFd = profileFd;
data.initAutoStopProfiler = false;
sendMessage(H.BIND_APPLICATION, data);
}
这里首先调用会给H handler发送两个消息，一个是SET_CORE_SETTINGS；另一个是BIND_APPLICATION。SET_CORE_SETTINGS主要是获取系统的设定并设置到ActivityThread中。BIND_APPLICATION用于启动Application并安装所有的provider，并回调Applicant的oncreate方法：
private void handleBindApplication(AppBindData data) {
mBoundApplication = data;
mConfiguration = new Configuration(data.config);
mCompatConfiguration = new Configuration(data.config);
mProfiler = new Profiler();
mProfiler.profileFile = data.initProfileFile;
mProfiler.profileFd = data.initProfileFd;
mProfiler.autoStopProfiler = data.initAutoStopProfiler;
Process.setArgV0(data.processName);
android.ddm.DdmHandleAppName.setAppName(data.processName,
UserHandle.myUserId());
TimeZone.setDefault(null);
Locale.setDefault(data.config.locale);
mResourcesManager.applyConfigurationToResourcesLocked(data.config, data.compatInfo);
mCurDefaultDisplayDpi = data.config.densityDpi;
applyCompatConfiguration(mCurDefaultDisplayDpi);
data.info = getPackageInfoNoCheck(data.appInfo, data.compatInfo);
if ((data.appInfo.flags&ApplicationInfo.FLAG_SUPPORTS_SCREEN_DENSITIES)
== 0) {
mDensityCompatMode = true;
Bitmap.setDefaultDensity(DisplayMetrics.DENSITY_DEFAULT);
}
updateDefaultDensity();
final ContextImpl appContext = new ContextImpl();
appContext.init(data.info, null, this);
if (!Process.isIsolated()) {
final File cacheDir = appContext.getCacheDir();
if (cacheDir != null) {
System.setProperty("java.io.tmpdir", cacheDir.getAbsolutePath());
setupGraphicsSupport(data.info, cacheDir);
} else {
Log.e(TAG, "Unable to setupGraphicsSupport due to missing cache directory");
}
}
if ((data.appInfo.flags &
(ApplicationInfo.FLAG_SYSTEM |
ApplicationInfo.FLAG_UPDATED_SYSTEM_APP)) != 0) {
StrictMode.conditionallyEnableDebugLogging();
}
if (data.appInfo.targetSdkVersion > 9) {
StrictMode.enableDeathOnNetwork();
}
if (data.enableOpenGlTrace) {
GLUtils.setTracingLevel(1);
}
boolean appTracingAllowed = (data.appInfo.flags&ApplicationInfo.FLAG_DEBUGGABLE) != 0;
Trace.setAppTracingAllowed(appTracingAllowed);
if (data.instrumentationName != null) {
} else {
mInstrumentation = new Instrumentation();
}
if ((data.appInfo.flags&ApplicationInfo.FLAG_LARGE_HEAP) != 0) {
dalvik.system.VMRuntime.getRuntime().clearGrowthLimit();
}
final StrictMode.ThreadPolicy savedPolicy = StrictMode.allowThreadDiskWrites();
try {
Application app = data.info.makeApplication(data.restrictedBackupMode, null);
mInitialApplication = app;
if (!data.restrictedBackupMode) {
List<ProviderInfo> providers = data.providers;
if (providers != null) {
installContentProviders(app, providers);
mH.sendEmptyMessageDelayed(H.ENABLE_JIT, 10*1000);
}
}
try {
mInstrumentation.onCreate(data.instrumentationArgs);
}
catch (Exception e) {
}
try {
mInstrumentation.callApplicationOnCreate(app);
} catch (Exception e) {
}
} finally {
StrictMode.setThreadPolicy(savedPolicy);
}
}
handleBindApplication中首先修改process的名字，然后恢复时区和位置信息。通过getPackageInfoNoCheck方法获取一个LoadedApk对象，并把packageName和LoadedApk添加到全局的mPackages中。在handleBindApplication中会构造整个application运行的context环境，并构造一个Instrumentation对象用于启动Activity。如果不是restrictedBackupMode模式，就调用installContentProviders去安装这个APK里面所有的provider，关于installContentProviders，前面在介绍安装systemProvider的时候已经讲解过了。最后调用mInstrumentation.callApplicationOnCreate去回调Application的onCreate方法，如果在APK中有继承Applicantion的class，则回调对应class的oncreate方法。
attachApplicationLocked的第二件事情是调用StackSupervisor的attachApplicationLocked去启动ActivityStack栈顶的Activity：
boolean attachApplicationLocked(ProcessRecord app, boolean headless) throws Exception {
boolean didSomething = false;
final String processName = app.processName;
for (int stackNdx = mStacks.size() - 1; stackNdx >= 0; --stackNdx) {
final ActivityStack stack = mStacks.get(stackNdx);
if (!isFrontStack(stack)) {
continue;
}
ActivityRecord hr = stack.topRunningActivityLocked(null);
if (hr != null) {
if (hr.app == null && app.uid == hr.info.applicationInfo.uid
&& processName.equals(hr.processName)) {
try {
if (headless) {
} else if (realStartActivityLocked(hr, app, true, true)) {
didSomething = true;
}
} catch (Exception e) {
Slog.w(TAG, "Exception in new application when starting activity "
+ hr.intent.getComponent().flattenToShortString(), e);
throw e;
}
}
}
}
if (!didSomething) {
ensureActivitiesVisibleLocked(null, 0);
}
return didSomething;
}
attachApplicationLocked从ActivityTask中的TaskRecord列表中获取处于栈顶的ActivityRecord对象，也就是我们要启动的launcher。然后调用realStartActivityLocked方法去完成启动：
final boolean realStartActivityLocked(ActivityRecord r,
ProcessRecord app, boolean andResume, boolean checkConfig)
throws RemoteException {
r.startFreezingScreenLocked(app, 0);
mWindowManager.setAppVisibility(r.appToken, true);
r.startLaunchTickingLocked();
if (checkConfig) {
Configuration config = mWindowManager.updateOrientationFromAppTokens(
mService.mConfiguration,
r.mayFreezeScreenLocked(app) ? r.appToken : null);
mService.updateConfigurationLocked(config, r, false, false);
}
r.app = app;
app.waitingToKill = null;
r.launchCount++;
r.lastLaunchTime = SystemClock.uptimeMillis();
int idx = app.activities.indexOf(r);
if (idx < 0) {
app.activities.add(r);
}
mService.updateLruProcessLocked(app, true, null);
mService.updateOomAdjLocked();
final ActivityStack stack = r.task.stack;
try {
if (app.thread == null) {
throw new RemoteException();
}
List<ResultInfo> results = null;
List<Intent> newIntents = null;
if (andResume) {
results = r.results;
newIntents = r.newIntents;
}
if (r.isHomeActivity() && r.isNotResolverActivity()) {
mService.mHomeProcess = r.task.mActivities.get(0).app;
}
mService.ensurePackageDexOpt(r.intent.getComponent().getPackageName());
r.sleeping = false;
r.forceNewConfig = false;
mService.showAskCompatModeDialogLocked(r);
r.compat = mService.compatibilityInfoForPackageLocked(r.info.applicationInfo);
String profileFile = null;
ParcelFileDescriptor profileFd = null;
boolean profileAutoStop = false;
app.hasShownUi = true;
app.pendingUiClean = true;
app.forceProcessStateUpTo(ActivityManager.PROCESS_STATE_TOP);
app.thread.scheduleLaunchActivity(new Intent(r.intent), r.appToken,
System.identityHashCode(r), r.info,
new Configuration(mService.mConfiguration), r.compat,
app.repProcState, r.icicle, results, newIntents, !andResume,
mService.isNextTransitionForward(), profileFile, profileFd,
profileAutoStop);
r.launchFailed = false;
if (stack.updateLRUListLocked(r)) {
}
if (andResume) {
stack.minimalResumeActivityLocked(r);
} else {
r.state = ActivityState.STOPPED;
r.stopped = true;
}
return true;
}
realStartActivityLocked方法中首先记录Activity启动时间和状态，最终调用ActivityThread的scheduleLaunchActivity去启动Activity。scheduleLaunchActivity方法中，通过传入的参数构造一个ActivityClientRecord，并发送LAUNCH_ACTIVITY消息给H handler，并最终调用handleLaunchActivity方法：
private void handleLaunchActivity(ActivityClientRecord r, Intent customIntent) {
unscheduleGcIdler();
Activity a = performLaunchActivity(r, customIntent);
if (a != null) {
r.createdConfig = new Configuration(mConfiguration);
Bundle oldState = r.state;
handleResumeActivity(r.token, false, r.isForward,
!r.activity.mFinished && !r.startsNotResumed);
if (!r.activity.mFinished && r.startsNotResumed) {
}
} else {
}
}
在handleLaunchActivity中主要执行两个步骤，一是performLaunchActivity，这个方法用于加载对象Activity的class文件，并且实例化一个Activity对象，调用createBaseContextForActivity去创建一个ContextImpl对象并attach上这个Activity。最后通过mInstrumentation回调Activity的OnCreate、OnStart、OnRestoreInstanceState、OnPostCreate这几个方法，并把ActivityClientRecord对象加入到ActivityThread的mActivities数组；二是调用handleResumeActivity回调Activity的OnResume方法：
final void handleResumeActivity(IBinder token, boolean clearHide, boolean isForward,
boolean reallyResume) {
unscheduleGcIdler();
ActivityClientRecord r = performResumeActivity(token, clearHide);
if (r != null) {
final Activity a = r.activity;
final int forwardBit = isForward ?
WindowManager.LayoutParams.SOFT_INPUT_IS_FORWARD_NAVIGATION : 0;
boolean willBeVisible = !a.mStartedActivity;
if (!willBeVisible) {
try {
willBeVisible = ActivityManagerNative.getDefault().willActivityBeVisible(
a.getActivityToken());
} catch (RemoteException e) {
}
}
if (r.window == null && !a.mFinished && willBeVisible) {
r.window = r.activity.getWindow();
View decor = r.window.getDecorView();
decor.setVisibility(View.INVISIBLE);
ViewManager wm = a.getWindowManager();
WindowManager.LayoutParams l = r.window.getAttributes();
a.mDecor = decor;
l.type = WindowManager.LayoutParams.TYPE_BASE_APPLICATION;
l.softInputMode |= forwardBit;
if (a.mVisibleFromClient) {
a.mWindowAdded = true;
wm.addView(decor, l);
}
} else if (!willBeVisible) {
if (localLOGV) Slog.v(
TAG, "Launch " + r + " mStartedActivity set");
r.hideForNow = true;
}
cleanUpPendingRemoveWindows(r);
if (!r.activity.mFinished && willBeVisible
&& r.activity.mDecor != null && !r.hideForNow) {
WindowManager.LayoutParams l = r.window.getAttributes();
if ((l.softInputMode
& WindowManager.LayoutParams.SOFT_INPUT_IS_FORWARD_NAVIGATION)
!= forwardBit) {
l.softInputMode = (l.softInputMode
& (~WindowManager.LayoutParams.SOFT_INPUT_IS_FORWARD_NAVIGATION))
| forwardBit;
if (r.activity.mVisibleFromClient) {
ViewManager wm = a.getWindowManager();
View decor = r.window.getDecorView();
wm.updateViewLayout(decor, l);
}
}
r.activity.mVisibleFromServer = true;
mNumVisibleActivities++;
if (r.activity.mVisibleFromClient) {
r.activity.makeVisible();
}
}
if (!r.onlyLocalRequest) {
r.nextIdle = mNewActivities;
mNewActivities = r;
if (localLOGV) Slog.v(
TAG, "Scheduling idle handler for " + r);
Looper.myQueue().addIdleHandler(new Idler());
}
r.onlyLocalRequest = false;
// Tell the activity manager we have resumed.
if (reallyResume) {
try {
ActivityManagerNative.getDefault().activityResumed(token);
} catch (RemoteException ex) {
}
}
} else {
}
}
handleResumeActivity调用performResumeActivity回调activity的performResume方法，并调用WMS的方法让这个Activity显示出来。并且向ActivityThread所在的Looper注册IdleHandler，用于在Activtiy处理空闲的时候回调。到这里启动launcher的流程就介绍完了。
关于TaskRecord、ProcessRecord、ActivityRecord和ActvityStack的关系如下，我们在下一节介绍启动一个应用的时候再来具体分析。
