学步园

一、先分析Native层：

1、C++基类SocketListener：

1. class SocketListener {
   
2.     int mSock;
   
3.     const
   char *mSocketName;
   
4.     SocketClientCollection *mClients;
   
5.     pthread_mutex_t mClientsLock;
   
6.     bool mListen;
   
7.     int mCtrlPipe[2];
   
8.     pthread_t mThread;
   
9.  
10. public:
    
11.     SocketListener(const
    char *socketNames, bool listen);
    
12.     SocketListener(int socketFd, bool listen);
    
13.  
14.     virtual ~SocketListener();
    
15.     int startListener();
    
16.     int stopListener();
    
17.  
18.     void sendBroadcast(int code, const
    char *msg, bool addErrno);
    
19.     void sendBroadcast(const
    char *msg);
    
20.  
21. protected:
    
22.     virtual bool onDataAvailable(SocketClient *c) = 0;
    
23.  
24. private:
    
25.     static
    void *threadStart(void *obj);
    
26.     void runListener();
    
27. };
    
28. #endif
    

看关键接口runListener：

1. void SocketListener::runListener() {
   
2.  
3.     while(1) {
   
4.         SocketClientCollection::iterator it;
   
5.         fd_set read_fds;
   
6.         int rc = 0;
   
7.         int max = 0;
   
8.  
9.         FD_ZERO(&read_fds);
   
10.  
11.         if (mListen) {
    
12.             max = mSock;
    
13.             FD_SET(mSock, &read_fds);
    
14.         }
    
15.  
16.         FD_SET(mCtrlPipe[0], &read_fds);
    
17.         if (mCtrlPipe[0] > max)
    
18.             max = mCtrlPipe[0];
    
19.  
20.         pthread_mutex_lock(&mClientsLock);
    
21.         for (it = mClients->begin(); it != mClients->end(); ++it) {
    
22.             FD_SET((*it)->getSocket(), &read_fds);
    
23.             if ((*it)->getSocket() > max)
    
24.                 max = (*it)->getSocket();
    
25.         }
    
26.         pthread_mutex_unlock(&mClientsLock);
    
27.  
28.         if ((rc = select(max + 1, &read_fds, NULL, NULL, NULL)) < 0) {
    
29.             SLOGE("select failed (%s)", strerror(errno));
    
30.             sleep(1);
    
31.             continue;
    
32.         } else
    if (!rc)
    
33.             continue;
    
34.  
35.         if (FD_ISSET(mCtrlPipe[0], &read_fds))
    
36.             break;
    
37.         if (mListen && FD_ISSET(mSock, &read_fds)) {
    
38.             struct sockaddr addr;
    
39.             socklen_t alen = sizeof(addr);
    
40.             int c;
    
41.  
42.             if ((c = accept(mSock, &addr, &alen)) < 0) {
    
43.                 SLOGE("accept failed (%s)", strerror(errno));
    
44.                 sleep(1);
    
45.                 continue;
    
46.             }
    
47.             pthread_mutex_lock(&mClientsLock);
    
48.             mClients->push_back(new SocketClient(c));
    
49.             pthread_mutex_unlock(&mClientsLock);
    
50.         }
    
51.  
52.         do {
    
53.             pthread_mutex_lock(&mClientsLock);
    
54.             for (it = mClients->begin(); it != mClients->end(); ++it) {
    
55.                 int fd = (*it)->getSocket();
    
56.                 if (FD_ISSET(fd, &read_fds)) {
    
57.                     pthread_mutex_unlock(&mClientsLock);
    
58.                     if (!onDataAvailable(*it)) {//由子类实现的接口。
    
59.                         close(fd);
    
60.                         pthread_mutex_lock(&mClientsLock);
    
61.                         delete *it;
    
62.                         it = mClients->erase(it);
    
63.                         pthread_mutex_unlock(&mClientsLock);
    
64.                     }
    
65.                     FD_CLR(fd, &read_fds);
    
66.                     continue;
    
67.                 }
    
68.             }
    
69.             pthread_mutex_unlock(&mClientsLock);
    
70.         } while (0);
    
71.     }
    
72. }
    

2、他的第一继承者：

1. #include "SocketListener.h"
   
2. #include "FrameworkCommand.h"
   
3.  
4. class SocketClient;
   
5.  
6. class FrameworkListener : public SocketListener {
   
7. public:
   
8.     static
   const
   int CMD_ARGS_MAX = 16;
   
9. private:
   
10.     FrameworkCommandCollection *mCommands;
    
11.  
12. public:
    
13.     FrameworkListener(const
    char *socketName);
    
14.     virtual ~FrameworkListener() {}
    
15.  
16. protected:
    
17.     void registerCmd(FrameworkCommand *cmd);
    
18.     virtual
    bool onDataAvailable(SocketClient *c);
    
19.  
20. private:
    
21.     void dispatchCommand(SocketClient *c, char *data);
    
22. };
    

他的onDataAvailable接口实现：

1. bool FrameworkListener::onDataAvailable(SocketClient *c) {
   
2.     char buffer[255];
   
3.     int len;
   
4.  
5.     if ((len = read(c->getSocket(), buffer, sizeof(buffer) -1)) < 0) {
   
6.         SLOGE("read() failed (%s)", strerror(errno));
   
7.         return errno;
   
8.     } else
   if (!len)
   
9.         return
   false;
   
10.  
11.     int offset = 0;
    
12.     int i;
    
13.  
14.     for (i = 0; i < len; i++) {
    
15.         if (buffer[i] == '\0') {
    
16.             dispatchCommand(c, buffer + offset);
    
17.             offset = i + 1;
    
18.         }
    
19.     }
    
20.     return
    true;
    
21. }
    

3、实例：netd的CommandListener类：

1. class CommandListener : public FrameworkListener {
   
2.     static TetherController *sTetherCtrl;
   
3.     static NatController *sNatCtrl;
   
4.     static PppController *sPppCtrl;
   
5.     static PanController *sPanCtrl;
   
6.     static SoftapController *sSoftapCtrl;
   
7.     static UsbController *sUsbCtrl;
   
8.  
9. public:
   
10.     CommandListener();
    
11.     virtual ~CommandListener() {}
    
12.  
13. private:
    
14.  
15.     static
    int readInterfaceCounters(const
    char *iface, unsigned long *rx, unsigned long *tx);
    
16.  
17.     class UsbCmd : public NetdCommand {
    
18.     public:
    
19.         UsbCmd();
    
20.         virtual ~UsbCmd() {}
    
21.         int runCommand(SocketClient *c, int argc, char ** argv);
    
22.     };
    
23.  
24.     class SoftapCmd : public NetdCommand {
    
25.     public:
    
26.         SoftapCmd();
    
27.         virtual ~SoftapCmd() {}
    
28.         int runCommand(SocketClient *c, int argc, char ** argv);
    
29.     };
    
30.  
31.     class InterfaceCmd : public NetdCommand {
    
32.     public:
    
33.         InterfaceCmd();
    
34.         virtual ~InterfaceCmd() {}
    
35.         int runCommand(SocketClient *c, int argc, char ** argv);
    
36.     };
    
37.  
38.     class IpFwdCmd : public NetdCommand {
    
39.     public:
    
40.         IpFwdCmd();
    
41.         virtual ~IpFwdCmd() {}
    
42.         int runCommand(SocketClient *c, int argc, char ** argv);
    
43.     };
    
44.  
45.     class TetherCmd : public NetdCommand {
    
46.     public:
    
47.         TetherCmd();
    
48.         virtual ~TetherCmd() {}
    
49.         int runCommand(SocketClient *c, int argc, char ** argv);
    
50.     };
    
51.  
52.     class NatCmd : public NetdCommand {
    
53.     public:
    
54.         NatCmd();
    
55.         virtual ~NatCmd() {}
    
56.         int runCommand(SocketClient *c, int argc, char ** argv);
    
57.     };
    
58.  
59.     class ListTtysCmd : public NetdCommand {
    
60.     public:
    
61.         ListTtysCmd();
    
62.         virtual ~ListTtysCmd() {}
    
63.         int runCommand(SocketClient *c, int argc, char ** argv);
    
64.     };
    
65.  
66.     class PppdCmd : public NetdCommand {
    
67.     public:
    
68.         PppdCmd();
    
69.         virtual ~PppdCmd() {}
    
70.         int runCommand(SocketClient *c, int argc, char ** argv);
    
71.     };
    
72.  
73.     class PanCmd : public NetdCommand {
    
74.     public:
    
75.         PanCmd();
    
76.         virtual ~PanCmd() {}
    
77.         int runCommand(SocketClient *c, int argc, char ** argv);
    
78.     };
    
79. };
    

不能忘记NetdCommand类：

1. #include <sysutils/FrameworkCommand.h>
   
2.  
3. class NetdCommand : public FrameworkCommand {
   
4. public:
   
5.     NetdCommand(const
   char *cmd);
   
6.     virtual ~NetdCommand() {}
   
7. };
   
8. 4、分析一个子类ListTtysCmd：
   
9. CommandListener::ListTtysCmd::ListTtysCmd() :
   
10.                  NetdCommand("list_ttys") {
    
11. }
    
12.  
13. int CommandListener::ListTtysCmd::runCommand(SocketClient *cli,
    
14.                                              int argc, char **argv) {
    
15.     TtyCollection *tlist = sPppCtrl->getTtyList();
    
16.     TtyCollection::iterator it;
    
17.  
18.     for (it = tlist->begin(); it != tlist->end(); ++it) {
    
19.         cli->sendMsg(ResponseCode::TtyListResult, *it, false);
    
20.     }
    
21.  
22.     cli->sendMsg(ResponseCode::CommandOkay, "Ttys listed.", false);
    
23.     return 0;
    
24. }
    

Java层：

1. private
   void listenToSocket() throws IOException {
   
2.     LocalSocket socket = null;
   
3.  
4.     try {
   
5.         socket = new LocalSocket();
   
6.         LocalSocketAddress address = new LocalSocketAddress(mSocket,
   
7.                 LocalSocketAddress.Namespace.RESERVED);
   
8.  
9.         socket.connect(address);
   
10.  
11.         InputStream inputStream = socket.getInputStream();
    
12.         mOutputStream = socket.getOutputStream();
    
13.  
14.         mCallbacks.onDaemonConnected();
    
15.  
16.         byte[] buffer = new
    byte[BUFFER_SIZE];
    
17.         int start = 0;
    
18.  
19.         while (true) {
    
20.             int count = inputStream.read(buffer, start, BUFFER_SIZE - start);
    
21.             if (count < 0) break;
    
22.  
23.             // Add our starting point to the count and reset the start.
    
24.             count += start;
    
25.             start = 0;
    
26.  
27.             for (int i = 0; i < count; i++) {
    
28.                 if (buffer[i] == 0) {
    
29.                     String event = new String(buffer, start, i - start);
    
30.                     if (LOCAL_LOGD) Slog.d(TAG, String.format("RCV <- {%s}", event));
    
31.  
32.                     String[] tokens = event.split("
    ", 2);
    
33.                     try {
    
34.                         int code = Integer.parseInt(tokens[0]);
    
35.  
36.                         if (code >= ResponseCode.UnsolicitedInformational) {
    
37.                             mCallbackHandler.sendMessage(
    
38.                                     mCallbackHandler.obtainMessage(code, event));
    
39.                         } else {
    
40.                             try {
    
41.                                 mResponseQueue.put(event);
    
42.                             } catch (InterruptedException ex) {
    
43.                                 Slog.e(TAG, "Failed to put response onto queue", ex);
    
44.                             }
    
45.                         }
    
46.                     } catch (NumberFormatException nfe) {
    
47.                         Slog.w(TAG, String.format("Bad msg (%s)", event));
    
48.                     }
    
49.                     start = i + 1;
    
50.                 }
    
51.             }
    
52.  
53.             // We should end at the amount we read. If not, compact then
    
54.             // buffer and read again.
    
55.             if (start != count) {
    
56.                 final int remaining = BUFFER_SIZE - start;
    
57.                 System.arraycopy(buffer, start, buffer, 0, remaining);
    
58.                 start = remaining;
    
59.             } else {
    
60.                 start = 0;
    
61.             }
    
62.         }
    
63.     } catch (IOException ex) {
    
64.         Slog.e(TAG, "Communications error", ex);
    
65.         throw ex;
    
66.     } finally {
    
67.         synchronized (mDaemonLock) {
    
68.             if (mOutputStream != null) {
    
69.                 try {
    
70.                     mOutputStream.close();
    
71.                 } catch (IOException e) {
    
72.                     Slog.w(TAG, "Failed closing output stream", e);
    
73.                 }
    
74.                 mOutputStream = null;
    
75.             }
    
76.         }
    
77.  
78.         try {
    
79.             if (socket != null) {
    
80.                 socket.close();
    
81.             }
    
82.         } catch (IOException ex) {
    
83.             Slog.w(TAG, "Failed closing socket", ex);
    
84.         }
    
85.     }
    
86. }
    

sendCommandLocked接口

1. /**
   
2.   * Sends a command to the daemon with a single argument
   
3.   *
   
4.   * @param command The command to send to the daemon
   
5.   * @param argument The argument to send with the command (or null)
   
6.   */
   
7.  private
   void sendCommandLocked(String command, String argument)
   
8.          throws NativeDaemonConnectorException {
   
9.      if (command != null && command.indexOf('\0') >= 0) {
   
10.          throw
    new IllegalArgumentException("unexpected command: " + command);
    
11.      }
    
12.      if (argument != null && argument.indexOf('\0') >= 0) {
    
13.          throw
    new IllegalArgumentException("unexpected argument: " + argument);
    
14.      }
    
15.  
16.      if (LOCAL_LOGD) Slog.d(TAG, String.format("SND -> {%s} {%s}", command, argument));
    
17.      if (mOutputStream == null) {
    
18.          Slog.e(TAG, "No connection to daemon", new IllegalStateException());
    
19.          throw
    new NativeDaemonConnectorException("No output stream!");
    
20.      } else {
    
21.          StringBuilder builder = new StringBuilder(command);
    
22.          if (argument != null) {
    
23.              builder.append(argument);
    
24.          }
    
25.          builder.append('\0');
    
26.  
27.          try {
    
28.              mOutputStream.write(builder.toString().getBytes());
    
29.          } catch (IOException ex) {
    
30.              Slog.e(TAG, "IOException in sendCommand", ex);
    
31.          }
    
32.      }
    
33.  }