android - 关闭 Activity 时如何停止 Activity 的线程和套接字

Question

你好。我有一个使用 TCP 连接连接到 c++ 服务器的 android 应用程序。 我的第一个 Activity 让用户写入 ip 地址和端口以连接服务器，然后此 Activity 使用 Intent 调用另一个 Activity 。 第二个 Activity 进行套接字连接并运行几个线程。

第二个 Activity 也有一个断开按钮；当您按下该按钮时，它应该停止所有正在运行的线程，关闭套接字连接并返回 Activity 一，并在需要时让用户再次连接。我没能这样做。 我试过 socket.close() 但后来我的线程崩溃了，不允许重新连接。我也尝试过 this.onDestroy(); 或 this.finish(); Activity 关闭但它仍然连接到服务器。

如何在完成一个 Activity 时完成所有线程和套接字并返回到上一个 Activity ？

为了更清楚这里是我的代码:

第一个 Activity :

public class FirstActivity extends Activity {
 EditText editTextAddress, editTextPort; 
 Button buttonConnect, buttonClear;
 Intent intent;
 @Override
 protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_ipclient);

      editTextAddress = (EditText)findViewById(R.id.address);
      editTextPort = (EditText)findViewById(R.id.port);
      buttonConnect = (Button)findViewById(R.id.connect);  
 }
 public void onClickConnect(View v){
     String ip=editTextAddress.getText().toString();
     int port=Integer.valueOf(editTextPort.getText().toString());
     intent=new Intent(this,SecondActivity.class);
     Bundle extrasB=new Bundle();
     extrasB.putString("ip",ip);
     extrasB.putInt("port",port);
     intent.putExtras(extrasB);
     startActivity(intent);
 }
}

第二个 Activity

public class SecondActivity extends Activity {
....

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_client_late);
    .....
    updateConversationHandler = new Handler();
    new Thread(new ClientThread()).start();
    sendImage=new SendImage();
    sendImage.execute();
 }
    public class SendImage extends AsyncTask<Void,Void,Void>{
    @Override
    protected Void doInBackground(Void... arg0){
        .....
    }
}
class ClientThread implements Runnable {

    @Override
    public void run() {

        thread1=Thread.currentThread();
        try {
            InetAddress serverAddr = InetAddress.getByName(SERVER_IP);
            socket = new Socket(serverAddr, SERVERPORT);

            socketTE = new Socket(serverAddr, SERVERPORT);
            CommunicationThread commThread = new CommunicationThread(socketTE);
            new Thread(commThread).start();
        } catch (UnknownHostException e1) {
            e1.printStackTrace();
        } catch (IOException e1) {
            e1.printStackTrace();
        }
    }

}

class CommunicationThread implements Runnable 
{

    private Socket clientSocket;
    private BufferedReader input;
    public CommunicationThread(Socket clientSocket) 
    {
        thread2=Thread.currentThread();
        this.clientSocket = clientSocket;
        ....

    }
    public void run() 
    {
        while (!Thread.currentThread().isInterrupted()) 
        {
            .....                   
        }
    }
}

class updateUIThread implements Runnable 
{
    private String msg;
    public updateUIThread(String str) 
    {
        thread3=Thread.currentThread();
        ...
    }
    @Override
    public void run() 
    {                     
            ....
    }
}

**public void disconnectButtonOnCLick(View v) throws IOException{
    super.onStop();
    super.finish();
}**
@Override
protected void onDestroy() {
    super.onDestroy();
    sendImage.cancel(true);
    thread1.interrupt();        
    thread2.interrupt();
    thread3.interrupt();
    try {
        socket.close();
        socketTE.close();
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
}

}

Answer 1

对于异步任务:

@Override
    public void onPause(){
        super.onPause();
        if (sendImage!=null) {
            sendImage.cancel(true);
            }
}