3

我创建了一个多线程应用程序，但如果服务器不可用，它仍然会挂起。

在主活动中，我创建了以下方法：

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

    //bind GUI elements
    ...

    //start TCPConnection Service in a new thread
    establishTCPConnection();
    ...

}


private void establishTCPConnection(){
    TCPClientServiceThread = new Thread(null, backgroundConnection, "connection");
    TCPClientServiceThread.start();
}

..


private Runnable backgroundConnection = new Runnable(){
    public void run(){
        //establish TCP connection
        doEstablishTCPConnection();
    }
};

private void doEstablishTCPConnection()
{
    //start TCPConnection service
    startService(new Intent(this, TCPClientService.class));
}

这是 TCPClientService 类：

public class TCPClientService extends Service{

...

private String serverAddress = "192.168.1.5";
private int portNumber = 1000;



@Override
public void onCreate()
{
    //TODO: Actions to perform when service is created
    connectionAvailable = false;

    IntentFilter dataReceiverFilter;
    dataReceiverFilter = new IntentFilter(MotranetClient.MOTION_DATA_UPDATED);
    dataReceiver = new DataReceiver();
    registerReceiver(dataReceiver, dataReceiverFilter);

    EstablishConnection();
}

@Override
public IBinder onBind(Intent intent)
{
    //TODO: Replace with service binding implementation
    return null;
}

private void EstablishConnection()
{
    try {
           InetAddress serverAddr = InetAddress.getByName(serverAddress);
           Log.d("TCP", "C: Connecting...");
           Socket socket = new Socket(serverAddr, portNumber);
           String message = "testing connection";

               try {
                Log.d("TCP", "C: Sending: '" + message + "'");
                PrintWriter out = new PrintWriter( new BufferedWriter( new OutputStreamWriter(socket.getOutputStream())),true);
                out.println(message);
                Log.d("TCP", "C: Sent.");
                  Log.d("TCP", "C: Done.");
                  connectionAvailable = true;

             } catch(Exception e) {
                 Log.e("TCP", "S: Error", e);
                 connectionAvailable = false;

               } finally {
                  socket.close();
                  announceNetworkAvailability(connectionAvailable);
                }

         } catch (Exception e) {
              Log.e("TCP", "C: Error", e);
              announceNetworkAvailability(connectionAvailable);
         }
    }


}

当服务器不可用时，线路

Socket socket = new Socket(serverAddr, portNumber);

导致一些延迟，我相信这是挂起的原因。但是如果 TCPClientService 服务在自己的线程中执行，我不知道为什么这会影响主要活动的超时。

如果有人能展示如何防止应用程序在服务器不可用时挂起，我将非常感激。

4

1 回答 1

2

Android 平台总是在主事件线程中运行 Activity 和 Services 的生命周期方法。因此，您创建另一个线程，并从中调用 startService ...但是当创建并启动服务时，将从主事件线程调用 onCreate() 等方法，而不是从您的用户线程调用。

正确的方法是不要从另一个线程调用 startService，而是正常调用 startService，然后让 Service 从 onCreate() 中生成一个连接线程。

ssakl 的解决方案并没有解决我担心的基本问题。

于 2009-03-18T16:50:42.897 回答