Question

我有一个BufferedReader，当我尝试阅读它时，它只是挂起而且没有做任何事情，我这样做了吗？我在AsyncTask中使用它。

编辑：我有一台连接到Wi-Fi的平板电脑，它连接到我的电脑，它在端口5334上的172.20.104.203广播，我可以看到线程何时启动，但没有这一点。

这是我的代码：

try {
       final BufferedReader in = new BufferedReader(
       new InputStreamReader(socket.getInputStream()));       
       String line = null;
       while ((line = in.readLine()) != null) {
          final String msg;
          msg = (line);
          Log.d("DeviceActivity", msg);
       }
    } catch (Exception e) {
        e.printStackTrace();
        Log.e("ClientAcivtity: Exception",
        String.valueOf(e));
    }

修改我拥有所有正确的权限或任何东西，我在AsyncTask之外做这个并且它工作得很好，移动它因为我不想在主线程中。

- 修改，这是完整的代码。

public class NetworkTask extends AsyncTask<Void, byte[], Boolean> {
        Socket nsocket; // Network Socket
        InputStream nis; // Network Input Stream
        OutputStream nos; // Network Output Stream
        private Handler handler = new Handler();

        Boolean connected = false;

        public static final int PORT = 5334;
        public String SERVERIP = "172.20.104.203";

        Socket socket;

        @Override
        protected void onPreExecute() {
            Log.i("AsyncTask", "onPreExecute");
            InetAddress serverAddr;
            try {
                serverAddr = InetAddress.getByName(SERVERIP);
                socket = new Socket(serverAddr, PORT);
                connected = true;
            } catch (UnknownHostException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
                Log.e("ClientAcivtity: Exception", String.valueOf(e));
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
                Log.e("ClientAcivtity: Exception", String.valueOf(e));
            }
        }

        @Override
        protected Boolean doInBackground(Void... params) { // This runs on a
                                                            // different thread
            boolean result = false;

            try {

                Log.d("ClientActivity", "C: Connecting...");
                if (socket != null) {
                    int cont = 1;
                    while (cont == 1) {
                        try {
                            Log.d("ClientActivity", "C: Sending command.");
                            PrintWriter out = new PrintWriter(
                                    new BufferedWriter(new OutputStreamWriter(
                                            socket.getOutputStream())), true);
                            // where you issue the commands
                            out.println("getPos");
                            Log.d("ClientActivity", "C: Sent " + "getPos");

                        } catch (Exception e) {
                            Log.e("ClientAcivtity: Exception",
                                    String.valueOf(e));
                        }
                        try {
                            final BufferedReader in = new BufferedReader(
                                    new InputStreamReader(
                                            socket.getInputStream()));
                            String line = null;
                            while ((line = in.readLine()) != null) {
                                final String msg;
                                msg = (line);
                                Log.d("DeviceActivity", msg);
                            }
                        } catch (Exception e) {
                            e.printStackTrace();
                            Log.e("ClientAcivtity: Exception",
                                    String.valueOf(e));
                        }
                        cont--;
                    }

                    Log.d("ClientActivity", "C: Closed.");
                }
            } catch (Exception e) {
                Log.e("ClientAcivtity: Exception", String.valueOf(e));
            }

            return result;
        }

        @Override
        protected void onProgressUpdate(byte[]... values) {
            if (values.length > 0) {
                Log.i("AsyncTask", "onProgressUpdate: " + values[0].length
                        + " bytes received.");
            }
        }

        @Override
        protected void onCancelled() {
            Log.i("AsyncTask", "Cancelled.");
        }

        @Override
        protected void onPostExecute(Boolean result) {
            if (socket != null) {
                if (connected) {
                    if (result) {
                        Log.i("AsyncTask",
                                "onPostExecute: Completed with an Error.");
                        try {
                            socket.close();
                        } catch (IOException e) {
                            // TODO Auto-generated catch block
                            e.printStackTrace();
                        }
                    } else {
                        Log.i("AsyncTask", "onPostExecute: Completed.");
                        try {
                            socket.close();
                        } catch (IOException e) {
                            // TODO Auto-generated catch block
                            e.printStackTrace();
                        }
                    }
                }
            }
        }
    }

Answer 1

尝试这样做：

final BufferedReader in = new BufferedReader(new InputStreamReader(
                                                    socket.getInputStream()));
StringBuffer buf = new StringBuffer();
int i;
while((i = in.read()) != -1){
    buf.append((char) i);
}

String data = buf.toString();

Answer 2

从套接字读取是一个非常困难的问题，取决于套接字实际连接的位置以及另一方如何响应。

如果另一方速度非常快，它可以为套接字提供足够的数据，以便读取例程实际上正常工作。但是如果在任何类型的另一侧有一个延迟（只需要比你的读取例程慢，包括小的默认超时）那么你的读取就会失败，即使另一方可能有数据 - 只是到达有点太慢在插座上。

根据您的需要，您可以围绕读取程序包装自己的最小和最大计时器。

请提供更多信息，我们可以更好地了解这个问题。

在许多情况下，必须使最小超时足够大，以便另一方将数据推送到套接字 - 但是您可能还需要最长时间来确定等待数据到达的时间。

更新：

首先运行runnable来启动监控线程。如果需要，您可以在循环中使用monitoringCanRun来中断线程。并且monitoringThreadIsAlive可用于了解线程是否仍在运行。

    monitoringCanRun = true;
    new Thread(new Runnable() {
    public void run() {
        monitoringThreadIsAlive = true;
        performMonitoring();
        monitoringThreadIsAlive = false;
    }
    }).start();
}

和performMonitoring看起来像：

   public void performMonitoring() {
while (monitoringCanRun) {
   ... do your read in the while loop
    ...you might like to insert some delay before trying again...
    try { //we delay every partial read so we are not too fast for the other side
    Thread.sleep(100);
    } catch (InterruptedException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
    }
}

}

Answer 3

我的猜测是当你写出命令“getPos”时，底层的BufferedWriter实际上并没有在线上发送数据（你应该用tcpdump / wireshark验证这一点）。如果是这种情况，服务器不响应readLine（），因为它从未得到命令。要验证此声明，请在out.flush();

之后添加out.println("getPos");

真的，tcpdump可能会给你一个比论坛上任何人更好的答案。

另见http://developer.android.com/reference/java/io/BufferedWriter.html

异步任务，BufferedReader

3 个答案: