Question

public class Client extends AppCompatActivity  {

public static final String TAG = Client.class.getSimpleName();
public static final int ServerPORT = 3000;
public static final String ServerIP = "10.146.166.86";
EditText message;
TextView mainView;
ClientThread clientThread;
Thread thread;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_client);
    message = (EditText)findViewById(R.id.message);
    mainView = (TextView)findViewById(R.id.mainView);
}

public void updateMessage(final String message) {
    runOnUiThread(new Runnable() {
        @Override
        public void run() {
            mainView.append(message + "\n");
        }
    });
}

public void onClick(View view) {

    if (view.getId() == R.id.connectServer) {
        mainView.setText("");
        clientThread = new ClientThread();
        thread = new Thread(clientThread);
        thread.start();
        return;
    }

    if (view.getId() == R.id.sendMessage) {
        Log.i(TAG, "Message sent from client");
        clientThread.sendMessage(message.getText().toString());
    }
}

class ClientThread implements Runnable {

    private Socket socket;
    private BufferedReader input;

    @Override
    public void run() {
        try {
            InetAddress serverAdd = InetAddress.getByName(ServerIP);
            socket = new Socket(serverAdd, ServerPORT);
            while (!Thread.currentThread().isInterrupted()) {
                this.input = new BufferedReader(new InputStreamReader(socket.getInputStream()));
                String message = input.readLine();
                if (null == message || "Disconnect".contentEquals(message)) {
                    Thread.interrupted();
                    message = "Server Disconnected.";
                    updateMessage(getTime() + " | Server : " + message);
                    break;
                }

                updateMessage(getTime() + " | Server : " + message);
            }
        } catch (UnknownHostException e1) {
            e1.printStackTrace();
        } catch (IOException e2) {
            e2.printStackTrace();
        }
    }

    void sendMessage(String message) {
        try {
            if (null != socket) {
                PrintWriter out = new PrintWriter(new BufferedWriter(new OutputStreamWriter(socket.getOutputStream())), true);
                out.println(message);
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

String getTime() {
    SimpleDateFormat sdf = new SimpleDateFormat("HH:mm:ss");
    return sdf.format(new Date());
}
@Override
protected void onDestroy() {
    super.onDestroy();
    if (null != clientThread) {
        clientThread.sendMessage("Disconnect");
        clientThread = null;
    }
}
}

我写了一个简单的服务器 - 客户端TCP套接字连接，并一直在尝试连接主机和客户端。虽然我已经在另一个Thread（而不是mainThread）上运行了网络操作，但是当我尝试从客户端向我的服务器发送一个字符串时，它会抛出

android.os.NetworkOnMainThreadException.

对我来说似乎更奇怪，因为当我尝试切换主机和客户端设备时，现在我能够从客户端发送到我的服务器，但不能从服务器发送到客户端。然后，我得出结论，这应该归功于我的一个设备。一个运行Android 8，一个运行Android 6，似乎问题属于运行Android 8的问题。虽然我通过添加以下方法成功克服了这个问题：

StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();
StrictMode.setThreadPolicy(policy);

这对我来说似乎很奇怪，因为它的发生方式。它实际上取决于设备吗？

编辑：完整的错误消息。这很奇怪，因为它只发生在我的一个设备上。当我在设备之间切换角色时，它可以成功完成任务。

02-10 16:42:17.719 827-827/com.dev.kvuong2711.clienttcp I/Client: Message sent from client
02-10 16:42:17.720 827-827/com.dev.kvuong2711.clienttcp W/System.err: android.os.NetworkOnMainThreadException
02-10 16:42:17.721 827-827/com.dev.kvuong2711.clienttcp W/System.err:     at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1448)
02-10 16:42:17.721 827-827/com.dev.kvuong2711.clienttcp W/System.err:     at java.net.SocketOutputStream.socketWrite(SocketOutputStream.java:108)
02-10 16:42:17.721 827-827/com.dev.kvuong2711.clienttcp W/System.err:     at java.net.SocketOutputStream.write(SocketOutputStream.java:153)
02-10 16:42:17.721 827-827/com.dev.kvuong2711.clienttcp W/System.err:     at sun.nio.cs.StreamEncoder.writeBytes(StreamEncoder.java:221)
02-10 16:42:17.721 827-827/com.dev.kvuong2711.clienttcp W/System.err:     at sun.nio.cs.StreamEncoder.implFlushBuffer(StreamEncoder.java:291)
02-10 16:42:17.721 827-827/com.dev.kvuong2711.clienttcp W/System.err:     at sun.nio.cs.StreamEncoder.implFlush(StreamEncoder.java:295)
02-10 16:42:17.721 827-827/com.dev.kvuong2711.clienttcp W/System.err:     at sun.nio.cs.StreamEncoder.flush(StreamEncoder.java:141)
02-10 16:42:17.721 827-827/com.dev.kvuong2711.clienttcp W/System.err:     at java.io.OutputStreamWriter.flush(OutputStreamWriter.java:229)
02-10 16:42:17.722 827-827/com.dev.kvuong2711.clienttcp W/System.err:     at java.io.BufferedWriter.flush(BufferedWriter.java:254)
02-10 16:42:17.722 827-827/com.dev.kvuong2711.clienttcp W/System.err:     at java.io.PrintWriter.newLine(PrintWriter.java:482)
02-10 16:42:17.722 827-827/com.dev.kvuong2711.clienttcp W/System.err:     at com.dev.kvuong2711.clienttcp.Client$ClientThread.sendMessage(Client.java:105)
02-10 16:42:17.722 827-827/com.dev.kvuong2711.clienttcp W/System.err:     at com.dev.kvuong2711.clienttcp.Client.onClick(Client.java:68)
02-10 16:42:17.722 827-827/com.dev.kvuong2711.clienttcp W/System.err:     at java.lang.reflect.Method.invoke(Native Method)
02-10 16:42:17.722 827-827/com.dev.kvuong2711.clienttcp W/System.err:     at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:288)
02-10 16:42:17.722 827-827/com.dev.kvuong2711.clienttcp W/System.err:     at android.view.View.performClick(View.java:6256)
02-10 16:42:17.722 827-827/com.dev.kvuong2711.clienttcp W/System.err:     at android.view.View$PerformClick.run(View.java:24779)
02-10 16:42:17.722 827-827/com.dev.kvuong2711.clienttcp W/System.err:     at android.os.Handler.handleCallback(Handler.java:789)
02-10 16:42:17.722 827-827/com.dev.kvuong2711.clienttcp W/System.err:     at android.os.Handler.dispatchMessage(Handler.java:98)
02-10 16:42:17.723 827-827/com.dev.kvuong2711.clienttcp W/System.err:     at android.os.Looper.loop(Looper.java:180)
02-10 16:42:17.723 827-827/com.dev.kvuong2711.clienttcp W/System.err:     at android.app.ActivityThread.main(ActivityThread.java:6950)
02-10 16:42:17.723 827-827/com.dev.kvuong2711.clienttcp W/System.err:     at java.lang.reflect.Method.invoke(Native Method)
02-10 16:42:17.723 827-827/com.dev.kvuong2711.clienttcp W/System.err:     at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:240)
02-10 16:42:17.723 827-827/com.dev.kvuong2711.clienttcp W/System.err:     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:835)

Answer 1

sendMessage中的代码未在另一个线程上运行，因为您将其放在另一个名为“Thread”的类中。当您调用run()时，只有runnable的execute()方法在另一个线程上运行。所以你要么必须在new Thread()中调用sendMessage，要么将它放在某种线程安全变量或队列中，用run()方法检查循环，然后发送。

一直在另一个Thread上运行，但仍然抛出android.os.NetworkOnMainThreadException？

1 个答案: