android系统服务线程都驻留在SystemServer进程中，由SystemServer启动，在SystemServer.init2函数中，通过启动一个线程来启动各种系统服务线程。
public static final void init2() {
Slog.i(TAG, "Entered the Android system server!");
Thread thr = new ServerThread();// 创建一个线程
thr.setName("android.server.ServerThread");//设置线程名称
thr.start();/启动该线程
}
android系统服务都是在thr线程的run函数中启动：
public void run() {
EventLog.writeEvent(EventLogTags.BOOT_PROGRESS_SYSTEM_RUN,SystemClock.uptimeMillis());
Looper.prepare();//创建一个消息循环对象
android.os.Process.setThreadPriority(android.os.Process.THREAD_PRIORITY_FOREGROUND);
BinderInternal.disableBackgroundScheduling(true);
android.os.Process.setCanSelfBackground(false);
// Critical services...
try {
Slog.i(TAG, "Activity Manager");
//①启动ActivityManagerService服务线程
context = ActivityManagerService.main(factoryTest);
................................................
//②向ServiceManager注册自己
ActivityManagerService.setSystemProcess();
................................................
Slog.i(TAG, "System Content Providers");
//③安装系统Providers
ActivityManagerService.installSystemProviders();
................................................
//④设置ActivityManagerService的成员变量mWindowManager
ActivityManagerService.self().setWindowManager(wm);
................................................
} catch (RuntimeException e) {
Slog.e("System", "******************************************");
Slog.e("System", "************ Failure starting core service", e);
}
//⑤调用systemReady函数为系统准备各种服务
ActivityManagerService.self().systemReady(new Runnable() {
public void run() {
Slog.i(TAG, "Making services ready");
startSystemUi(contextF);
try {
if (batteryF != null) batteryF.systemReady();
} catch (Throwable e) {
reportWtf("making Battery Service ready", e);
}
try {
if (networkManagementF != null) networkManagementF.systemReady();
} catch (Throwable e) {
reportWtf("making Network Managment Service ready", e);
}
try {
if (networkStatsF != null) networkStatsF.systemReady();
} catch (Throwable e) {
reportWtf("making Network Stats Service ready", e);
}
try {
if (networkPolicyF != null) networkPolicyF.systemReady();
} catch (Throwable e) {
reportWtf("making Network Policy Service ready", e);
}
try {
if (connectivityF != null) connectivityF.systemReady();
} catch (Throwable e) {
reportWtf("making Connectivity Service ready", e);
}
try {
if (dockF != null) dockF.systemReady();
} catch (Throwable e) {
reportWtf("making Dock Service ready", e);
}
try {
if (usbF != null) usbF.systemReady();
} catch (Throwable e) {
reportWtf("making USB Service ready", e);
}
try {
if (uiModeF != null) uiModeF.systemReady();
} catch (Throwable e) {
reportWtf("making UI Mode Service ready", e);
}
try {
if (recognitionF != null) recognitionF.systemReady();
} catch (Throwable e) {
reportWtf("making Recognition Service ready", e);
}
Watchdog.getInstance().start();
// It is now okay to let the various system services start their
// third party code...
try {
if (appWidgetF != null) appWidgetF.systemReady(safeMode);
} catch (Throwable e) {
reportWtf("making App Widget Service ready", e);
}
try {
if (wallpaperF != null) wallpaperF.systemReady();
} catch (Throwable e) {
reportWtf("making Wallpaper Service ready", e);
}
try {
if (immF != null) immF.systemReady(statusBarF);
} catch (Throwable e) {
reportWtf("making Input Method Service ready", e);
}
try {
if (locationF != null) locationF.systemReady();
} catch (Throwable e) {
reportWtf("making Location Service ready", e);
}
try {
if (countryDetectorF != null) countryDetectorF.systemReady();
} catch (Throwable e) {
reportWtf("making Country Detector Service ready", e);
}
try {
if (throttleF != null) throttleF.systemReady();
} catch (Throwable e) {
reportWtf("making Throttle Service ready", e);
}
try {
if (networkTimeUpdaterF != null) networkTimeUpdaterF.systemReady();
} catch (Throwable e) {
reportWtf("making Network Time Service ready", e);
}
try {
if (textServiceManagerServiceF != null) textServiceManagerServiceF.systemReady();
} catch (Throwable e) {
reportWtf("making Text Services Manager Service ready", e);
}
}
});
Looper.loop();
Slog.d(TAG, "System ServerThread is exiting!");
}
第一：ActivityManagerService.main(factoryTest)
public static final Context main(int factoryTest) {
//①启动AThread线程来创建ActivityManagerService实例
AThread thr = new AThread();
thr.start();
synchronized (thr) {
while (thr.mService == null) {
try {
thr.wait();
} catch (InterruptedException e) {
}
}
}
//将创建的ActivityManagerService实例保存到ActivityManagerService的静态变量mSelf
ActivityManagerService m = thr.mService;
mSelf = m;
//②创建ActivityThread实例并保存到ActivityManagerService的静态变量mSystemThread
ActivityThread at = ActivityThread.systemMain();
mSystemThread = at;
Context context = at.getSystemContext();
context.setTheme(android.R.style.Theme_Holo);
m.mContext = context;
m.mFactoryTest = factoryTest;
//③创建一个ActivityStack实例，并保存到ActivityManagerService的成员变量mMainStack中
m.mMainStack = new ActivityStack(m, context, true);
//④向ServiceManager注册BatteryStatsService服务
m.mBatteryStatsService.publish(context);
//⑤向ServiceManager注册UsageStatsService服务
m.mUsageStatsService.publish(context);
synchronized (thr) {
//取消AThread线程等待，进入消息循环状态
thr.mReady = true;
thr.notifyAll();
}
//⑥调用startRunning函数
m.startRunning(null, null, null, null);
return context;
}
①启动AThread线程
static class AThread extends Thread {
ActivityManagerService mService;
boolean mReady = false;
public AThread() {
super("ActivityManager");
}
public void run() {
//创建消息循环对象
Looper.prepare();
android.os.Process.setThreadPriority(android.os.Process.THREAD_PRIORITY_FOREGROUND);
android.os.Process.setCanSelfBackground(false);
ActivityManagerService m = new ActivityManagerService();
synchronized (this) {
//创建ActivityManagerService实例
mService = m;
notifyAll();
}
//mReady = false，所以该线程处于等待
synchronized (this) {
while (!mReady) {
try {
wait();
} catch (InterruptedException e) {
}
}
}
// For debug builds, log event loop stalls to dropbox for analysis.
if (StrictMode.conditionallyEnableDebugLogging()) {
Slog.i(TAG, "Enabled StrictMode logging for AThread's Looper");
}
//开启该线程的消息循环
Looper.loop();
}
}
②创建ActivityThread实例
public static final ActivityThread systemMain() {
HardwareRenderer.disable(true);
ActivityThread thread = new ActivityThread();
thread.attach(true);
return thread;
}
private void attach(boolean system) {
//本地线程存储
sThreadLocal.set(this);
mSystemThread = system;//mSystemThread=true
if (!system) {
ViewRootImpl.addFirstDrawHandler(new Runnable() {
public void run() {
ensureJitEnabled();
}
});
android.ddm.DdmHandleAppName.setAppName("<pre-initialized>");
RuntimeInit.setApplicationObject(mAppThread.asBinder());
IActivityManager mgr = ActivityManagerNative.getDefault();
try {
mgr.attachApplication(mAppThread);
} catch (RemoteException ex) {
// Ignore
}
} else {
// Don't set application object here -- if the system crashes,
// we can't display an alert, we just want to die die die.
android.ddm.DdmHandleAppName.setAppName("system_process");
try {
mInstrumentation = new Instrumentation();
ContextImpl context = new ContextImpl();
context.init(getSystemContext().mPackageInfo, null, this);
//创建Application实例，并保存在成员变量mAllApplications中
Application app = Instrumentation.newApplication(Application.class, context);
mAllApplications.add(app);
mInitialApplication = app;
//调用应用程序的onCreate函数
app.onCreate();
} catch (Exception e) {
throw new RuntimeException(
"Unable to instantiate Application():" + e.toString(), e);
}
}
ViewRootImpl.addConfigCallback(new ComponentCallbacks2() {
public void onConfigurationChanged(Configuration newConfig) {
synchronized (mPackages) {
// We need to apply this change to the resources
// immediately, because upon returning the view
// hierarchy will be informed about it.
if (applyConfigurationToResourcesLocked(newConfig, null)) {
// This actually changed the resources! Tell
// everyone about it.
if (mPendingConfiguration == null ||
mPendingConfiguration.isOtherSeqNewer(newConfig)) {
mPendingConfiguration = newConfig;
queueOrSendMessage(H.CONFIGURATION_CHANGED, newConfig);
}
}
}
}
public void onLowMemory() {
}
public void onTrimMemory(int level) {
}
});
}
③创建一个ActivityStack实例
ActivityStack(ActivityManagerService service, Context context, boolean mainStack) {
mService = service;
mContext = context;
mMainStack = mainStack;
PowerManager pm =(PowerManager)context.getSystemService(Context.POWER_SERVICE);
mGoingToSleep = pm.newWakeLock(PowerManager.PARTIAL_WAKE_LOCK, "ActivityManager-Sleep");
mLaunchingActivity = pm.newWakeLock(PowerManager.PARTIAL_WAKE_LOCK, "ActivityManager-Launch");
mLaunchingActivity.setReferenceCounted(false);
}
④注册BatteryStatsService服务
public void publish(Context context) {
mContext = context;
ServiceManager.addService("batteryinfo", asBinder());
mStats.setNumSpeedSteps(new PowerProfile(mContext).getNumSpeedSteps());
mStats.setRadioScanningTimeout(mContext.getResources().getInteger(
com.android.internal.R.integer.config_radioScanningTimeout)* 1000L);
}
⑤注册UsageStatsService服务
public void publish(Context context) {
mContext = context;
ServiceManager.addService(SERVICE_NAME, asBinder());
}
⑥调用startRunning函数startRunning(null, null, null, null)
public final void startRunning(String pkg, String cls, String action,String data) {
synchronized(this) {
//mStartRunning = false
if (mStartRunning) {
return;
}
mStartRunning = true;
//mTopComponent=null
mTopComponent = pkg != null && cls != null? new ComponentName(pkg, cls) : null;
//mTopAction=Intent.ACTION_MAIN
mTopAction = action != null ? action : Intent.ACTION_MAIN;
//mTopData=null
mTopData = data;
if (!mSystemReady) {
return;
}
}
systemReady(null);
}
public void systemReady(final Runnable goingCallback) {
//goingCallback = null
synchronized(this) {
//mSystemReady = false
if (mSystemReady) {
if (goingCallback != null) goingCallback.run();
return;
}
// mDidUpdate = false
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);
} 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--;
}
}
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);
IIntentReceiver finisher = null;
if (i == ris.size()-1) {
finisher = new IIntentReceiver.Stub() {
public void performReceive(Intent intent, int resultCode,
String data, Bundle extras, boolean ordered,
boolean sticky) {
// The raw IIntentReceiver interface is called
// with the AM lock held, so redispatch to
// execute our code without the lock.
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());
broadcastIntentLocked(null, null, intent, null, finisher,
0, null, null, null, true, false, MY_PID, Process.SYSTEM_UID);
if (finisher != null) {
mWaitingUpdate = true;
}
}
}
if (mWaitingUpdate) {
return;
}
mDidUpdate = true;
}
mSystemReady = true;
if (!mStartRunning) {
return;
}
}
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");
}
}
// Now that we have cleaned up any update processes, we
// are ready to start launching real processes and know that
// we won't trample on them any more.
mProcessesReady = true;
}
Slog.i(TAG, "System now ready");
EventLog.writeEvent(EventLogTags.BOOT_PROGRESS_AMS_READY,SystemClock.uptimeMillis());
synchronized(this) {
// Make sure we have no pre-ready processes sitting around.
if (mFactoryTest == SystemServer.FACTORY_TEST_LOW_LEVEL) {
ResolveInfo ri = mContext.getPackageManager().resolveActivity(new Intent(Intent.ACTION_FACTORY_TEST),STOCK_PM_FLAGS);
CharSequence errorMsg = null;
if (ri != null) {
ActivityInfo ai = ri.activityInfo;
ApplicationInfo app = ai.applicationInfo;
if ((app.flags&ApplicationInfo.FLAG_SYSTEM) != 0) {
mTopAction = Intent.ACTION_FACTORY_TEST;
mTopData = null;
mTopComponent = new ComponentName(app.packageName,
ai.name);
} else {
errorMsg = mContext.getResources().getText(com.android.internal.R.string.factorytest_not_system);
}
} else {
errorMsg = mContext.getResources().getText(com.android.internal.R.string.factorytest_no_action);
}
if (errorMsg != null) {
mTopAction = null;
mTopData = null;
mTopComponent = null;
Message msg = Message.obtain();
msg.what = SHOW_FACTORY_ERROR_MSG;
msg.getData().putCharSequence("msg", errorMsg);
mHandler.sendMessage(msg);
}
}
}
retrieveSettings();
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);
}
}
}
} catch (RemoteException ex) {
// pm is in same process, this will never happen.
}
}
// Start up initial activity.
mBooting = true;
try {
if (AppGlobals.getPackageManager().hasSystemUidErrors()) {
Message msg = Message.obtain();
msg.what = SHOW_UID_ERROR_MSG;
mHandler.sendMessage(msg);
}
} catch (RemoteException e) {
}
mMainStack.resumeTopActivityLocked(null);
}
}
第二：ActivityManagerService.setSystemProcess()
public static void setSystemProcess() {
try {
ActivityManagerService m = mSelf;
ServiceManager.addService("activity", m);
ServiceManager.addService("meminfo", new MemBinder(m));
ServiceManager.addService("gfxinfo", new GraphicsBinder(m));
if (MONITOR_CPU_USAGE) {
ServiceManager.addService("cpuinfo", new CpuBinder(m));
}
ServiceManager.addService("permission", new PermissionController(m));
//把应用程序框架层下面的android包加载进来
ApplicationInfo info =mSelf.mContext.getPackageManager().getApplicationInfo("android", STOCK_PM_FLAGS);
mSystemThread.installSystemApplicationInfo(info);
synchronized (mSelf) {
ProcessRecord app = mSelf.newProcessRecordLocked(
mSystemThread.getApplicationThread(), info,info.processName);
app.persistent = true;
app.pid = MY_PID;
app.maxAdj = ProcessList.SYSTEM_ADJ;
mSelf.mProcessNames.put(app.processName, app.info.uid, app);
synchronized (mSelf.mPidsSelfLocked) {
mSelf.mPidsSelfLocked.put(app.pid, app);
}
mSelf.updateLruProcessLocked(app, true, true);
}
} catch (PackageManager.NameNotFoundException e) {
throw new RuntimeException(
"Unable to find android system package", e);
}
}
第三：ActivityManagerService.installSystemProviders()
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();
}
第三：ActivityManagerService.systemReady()
