客户端-服务器 android 聊天应用程序 - NetworkOnMainThreadException [重复]

Question

我正在为 android 轻松聊天。 我正在使用this tutorial 这样做。我有简单的 android 客户端和 java 客户端。

我从几个步骤开始：

1. 启动服务器||消息服务器：“等待客户端连接”
2. 启动客户端||服务器中没有消息
3. 点击按钮||消息服务器：“客户端已连接”和“来自客户端的消息： 已连接”和“服务器已结束。”
4. Android 客户端崩溃并出现 NetworkOnMainThreadException

步骤 3 的消息将出现在创建客户端上，所以当我启动应用程序时。当我单击按钮时，它应该向服务器发送消息。它因此错误而崩溃：

01-10 10:31:26.892 27458-27458/com.example.rachel.testapp E/AndroidRuntime: FATAL EXCEPTION: main
 Process: com.example.rachel.testapp, PID: 27458
 java.lang.IllegalStateException: Could not execute method for android:onClick
     at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:293)
     at android.view.View.performClick(View.java:5637)
     at android.view.View$PerformClick.run(View.java:22429)
     at android.os.Handler.handleCallback(Handler.java:751)
     at android.os.Handler.dispatchMessage(Handler.java:95)
     at android.os.Looper.loop(Looper.java:154)
     at android.app.ActivityThread.main(ActivityThread.java:6119)
     at java.lang.reflect.Method.invoke(Native Method)
     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886)
     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776)
  Caused by: java.lang.reflect.InvocationTargetException
     at java.lang.reflect.Method.invoke(Native Method)
     at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:288)
     at android.view.View.performClick(View.java:5637) 
     at android.view.View$PerformClick.run(View.java:22429) 
     at android.os.Handler.handleCallback(Handler.java:751) 
     at android.os.Handler.dispatchMessage(Handler.java:95) 
     at android.os.Looper.loop(Looper.java:154) 
     at android.app.ActivityThread.main(ActivityThread.java:6119) 
     at java.lang.reflect.Method.invoke(Native Method) 
     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886) 
     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776) 
  Caused by: android.os.NetworkOnMainThreadException
     at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1303)
     at java.net.SocketOutputStream.socketWrite(SocketOutputStream.java:111)
     at java.net.SocketOutputStream.write(SocketOutputStream.java:157)
     at sun.nio.cs.StreamEncoder.writeBytes(StreamEncoder.java:221)
     at sun.nio.cs.StreamEncoder.implFlushBuffer(StreamEncoder.java:291)
     at sun.nio.cs.StreamEncoder.implFlush(StreamEncoder.java:295)
     at sun.nio.cs.StreamEncoder.flush(StreamEncoder.java:141)
     at java.io.OutputStreamWriter.flush(OutputStreamWriter.java:229)
     at java.io.BufferedWriter.flush(BufferedWriter.java:254)
     at com.example.rachel.testapp.MainActivity.sendMessage(MainActivity.java:88)
     at java.lang.reflect.Method.invoke(Native Method) 
     at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:288) 
     at android.view.View.performClick(View.java:5637) 
     at android.view.View$PerformClick.run(View.java:22429) 
     at android.os.Handler.handleCallback(Handler.java:751) 
     at android.os.Handler.dispatchMessage(Handler.java:95) 
     at android.os.Looper.loop(Looper.java:154) 
     at android.app.ActivityThread.main(ActivityThread.java:6119) 
     at java.lang.reflect.Method.invoke(Native Method) 
     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886) 
     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776) 

我有这样的安卓应用

public class MainActivity extends AppCompatActivity
{
    private static final String hostname = "localhost";
    private static final int portnumber = 60125;
    private static final String debugString = "debug";
    private Socket socket = null;

    @Override
    protected void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        new Thread()
        {
            @Override
            public void run()
            {
                try
                {
                    Log.i(debugString, "Attempting to connect to server");
                    socket = new Socket(hostname, portnumber);
                    Log.i(debugString, "Connection established");

                    BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(socket.getOutputStream()));
                    bw.write("Connected");
                    bw.newLine();
                    bw.flush();

                    BufferedReader br = new BufferedReader(new InputStreamReader(socket.getInputStream()));
                    System.out.println("Message from server:" + br.readLine());


                } catch (IOException e)

                {
                    Log.e(debugString, e.getMessage());
                    //e.printStackTrace();
                }
            }
        }.start();



    }

    public void sendMessage(View view)
    {
        Toast.makeText(getApplicationContext(), "Klik", Toast.LENGTH_LONG).show();

        EditText editText = (EditText) findViewById(R.id.editText);
        BufferedWriter bw =null;

        try
        {
            bw = new BufferedWriter(new OutputStreamWriter(socket.getOutputStream()));

            bw.write(editText.getText().toString());
            bw.newLine();
            bw.flush();
        }
        catch (IOException e)
        {
            Log.e(debugString, e.getMessage());
        }




    }

}

还有java服务器

public class main 
{

    private static final int portnumber = 60125;

    public static void main(String[] args) 
    {
        ServerSocket serverSocket = null;
        try
        {
            System.out.println("Serwer port: "+ portnumber);
            serverSocket = new ServerSocket(portnumber);

            System.out.println("Waiting to connect");
            Socket socket = serverSocket.accept();
            System.out.println("Client connected");

            BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(socket.getOutputStream()));
            bw.write("Message from server");
            bw.newLine();
            bw.flush();

            BufferedReader br = new BufferedReader(new InputStreamReader(socket.getInputStream()));
            String data;
            while((data = br.readLine()) != null)
            System.out.println("Message from client:"+data);


            System.out.println("Server has ended.");
        }
        catch(IOException e)
        {
            e.printStackTrace();            
        }

    }




}

Answer 1

您不能在主线程上进行网络操作。在后台任务中执行此操作。最好使用AsyncTask 或者改成这个

 new Thread(new Runnable() {
            @Override
            public void run() {
                try
                {
                    Log.i(debugString, "Attempting to connect to server");
                    socket = new Socket(hostname, portnumber);
                    Log.i(debugString, "Connection established");

                    BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(socket.getOutputStream()));
                    bw.write("Connected");
                    bw.newLine();
                    bw.flush();

                    BufferedReader br = new BufferedReader(new InputStreamReader(socket.getInputStream()));
                    System.out.println("Message from server:" + br.readLine());


                } catch (IOException e)

                {
                    Log.e(debugString, e.getMessage());
                    //e.printStackTrace();
                }
            }
        }).start();