java - 异步任务中的 getInputStream

Question

我有一个 Activity ，它调用异步任务以通过预定义的 InetAddress 接受套接字连接。

异步任务调用另一个异步任务来监听消息。但它卡在获取输入流上

我已经绞尽脑汁好几个小时了，但无法弄清楚它为什么挂起......请帮忙。

public void startSocketListener(InetAddress groupOwnerAddress) {
    // TODO Auto-generated method stub
    AcceptClientThread accept;
    try {
        accept = new AcceptClientThread();
        accept.execute();
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }


}

public class AcceptClientThread extends AsyncTask<Void, String, String>{

    public AcceptClientThread() throws IOException{

    }

    @Override
    protected void onCancelled() {
        // TODO Auto-generated method stub
        try {
            serverSocket.close();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            Log.e("CONNECTION ERR", "Could not close serverSocket " + e.toString());
        }
        super.onCancelled();
    }

    @Override
    protected String doInBackground(Void... params) {

        try {
            serverSocket = new ServerSocket(port);
        } catch (IOException e) {
            Log.e("CONNECTION ERR","Could not listen on port: " + port);
            onCancelled();
        }

        while (listening){
            try {
                Log.i("CONNECTION", "AWAITING CONNECTION TO CLIENT");
                Socket newSocket = serverSocket.accept();
                Log.i("CONNECTION", "CONNECTED TO CLIENT");
                ListenerThread lThread = new ListenerThread(newSocket);
                lThread.execute("Do it");
                Log.i("CONNECTION", "ACCEPTED CLIENT");
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
                onProgressUpdate("could not accept client");
            }

        }
        Log.i("CONNECTION", "close socket");
        try {
            serverSocket.close();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

        return "table connected";
    }

    @Override
    protected void onProgressUpdate(String... values) {
        super.onProgressUpdate(values);
        // received data is first element in the String
        //Toast.makeText(KitchenActivity.this, values[0], Toast.LENGTH_SHORT).show();
    }

}

public class ListenerThread extends AsyncTask<String, Order, Void> {

    private Socket socket;
    ObjectInputStream ois;

    public ListenerThread(Socket socket){
        this.socket = socket;
        try {
            ois = new ObjectInputStream(this.socket.getInputStream()); //hangs here
        } catch (StreamCorruptedException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }

Answer 1

根据The Docs

Threading rules

There are a few threading rules that must be followedfor this class to work properly:

The AsyncTask class must be loaded on the UI thread. This is doneautomatically as of JELLY_BEAN. The task instance must be created onthe UI thread.

您可以通过在 accept() 之后的第一个 AsyncTask 的 onPostExecute() 中调用新的 Thread 来处理此问题 成功，因为 onPostExecute() 在 UI

上运行

此外，在不进一步查看的情况下，我相信您会希望在第一个任务接受请求后打破 while 循环。然后，当您需要建立另一个连接时，您可以在 UI 中创建此任务的新实例，并再次执行。如果不看更长的时间，我对最后一部分并不乐观，但这似乎是正确的