java - 在android中启动asynctask时出错

Question

我正在两个不同的服务中启动两个异步任务，第一个任务正常工作并打开套接字，但第二个任务未启动，这里是我的应用程序基于 wifip2p 中的客户端套接字编程的代码。

    public class RecieveAudioService extends Service {

    String tag = "Recieve Audio Service";

    @Override
    public IBinder onBind(Intent intent) {
        return null;
    }

    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        Toast.makeText(getApplicationContext(), "Recieve audio :requesting to client", Toast.LENGTH_LONG).show();

        String[] param = {"h", "j", "k"};

        new request().execute();
        Log.v("Recieve Audio", "Inside Recieve audio service");

        return super.onStartCommand(intent, flags, startId);
    }

//===================== This class is sending request to server for connection when invocked
    public class request extends AsyncTask<String, String, String> {

        protected String doInBackground(String... arg0) {

            Log.v("second asyn", "this is second asynchronous task");

            try {

                Toast.makeText(getApplicationContext(), "Request to connect sent to server",
                        Toast.LENGTH_LONG).show();
                String toConnectDeviceIP = "192.168.49.1";
                Integer toConnectDevicePort = 8988;

                Socket connect = new Socket();

                connect.bind(null);
                connect.connect((new InetSocketAddress(toConnectDeviceIP, toConnectDevicePort)),
                        5000);
                Log.v(tag, "sent the connection request to clint");
                connect.close();

            } catch (Exception e) {
                // TODO Auto-generated catch block
                Log.v(tag, "" + e.toString());
                Toast.makeText(getApplicationContext(), "i found exception in connection"
                        +e.toString(), Toast.LENGTH_LONG).show();
            }

            return "success";
        }
    }
//====================================================================

}

Answer 1

您似乎是在 Android 4.x/3.x 上启动您的应用。在 Android 3.0 之前，AsyncTasks 是并发运行的，但更高版本(>3.x)的系统会依次执行任务。所以你有两个选择:

a) 使用Threads而不是AsyncTasks

b) 使用AsyncTask的executeOnExecutor来并发执行任务:

if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {
    task.executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR);
} else {
    task.execute();
}