不幸的是，Msger 已经停止了。致命例外：主要[重复]

Question

可能重复：
android.os.NetworkOnMainThreadException

当我尝试从第一个 Activity 的侦听器运行我的第二个 Activity 时，main.xml 有一个致命异常。当我取出 runTcpClient();在 TcpClient Thread() 上它加载得很好。

我遇到了使用 aSyncTask 管理 UI 线程：Android UI aSyncTask

TcpClientJava.java 代码

package com.mesger;

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.net.Socket;
import java.net.UnknownHostException;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.util.Log;



public class TcpClient extends Activity {
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    runTcpClient();
    finish();
}

private static final int TCP_SERVER_PORT = 1234;
private void runTcpClient() {
    try {
        Socket s = new Socket("10.0.2.2", TCP_SERVER_PORT);
        BufferedReader in = new BufferedReader(new InputStreamReader(s.getInputStream()));
        BufferedWriter out = new BufferedWriter(new OutputStreamWriter(s.getOutputStream()));
        //send output msg
        String outMsg = "TCP connecting to " + TCP_SERVER_PORT + System.getProperty("line.separator"); 
        out.write(outMsg);
        out.flush();
        Log.i("TcpClient", "sent: " + outMsg);
        //accept server response
        String inMsg = in.readLine() + System.getProperty("line.separator");
        Log.i("TcpClient", "received: " + inMsg);
        //close connection
        s.close();
    } catch (UnknownHostException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    } 
}
//replace runTcpClient() at onCreate with this method if you want to run tcp client as a service
private void runTcpClientAsService() {
    Intent lIntent = new Intent(this.getApplicationContext(), TcpClientService.class);
    this.startService(lIntent);
}

}

LOGCAT

11-12 13:41:22.725: D/gralloc_goldfish(738): Emulator without GPU emulation detected.
11-12 13:42:32.409: D/AndroidRuntime(738): Shutting down VM
11-12 13:42:32.409: W/dalvikvm(738): threadid=1: thread exiting with uncaught exception (group=0x40a13300)
11-12 13:42:32.465: E/AndroidRuntime(738): FATAL EXCEPTION: main
11-12 13:42:32.465: E/AndroidRuntime(738): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.i911.emergency.response/com.mesger.TcpClient}: android.os.NetworkOnMainThreadException
11-12 13:42:32.465: E/AndroidRuntime(738):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2059)
11-12 13:42:32.465: E/AndroidRuntime(738):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2084)
11-12 13:42:32.465: E/AndroidRuntime(738):  at android.app.ActivityThread.access$600(ActivityThread.java:130)
11-12 13:42:32.465: E/AndroidRuntime(738):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1195)
11-12 13:42:32.465: E/AndroidRuntime(738):  at android.os.Handler.dispatchMessage(Handler.java:99)
11-12 13:42:32.465: E/AndroidRuntime(738):  at android.os.Looper.loop(Looper.java:137)
11-12 13:42:32.465: E/AndroidRuntime(738):  at android.app.ActivityThread.main(ActivityThread.java:4745)
11-12 13:42:32.465: E/AndroidRuntime(738):  at java.lang.reflect.Method.invokeNative(Native Method)
11-12 13:42:32.465: E/AndroidRuntime(738):  at java.lang.reflect.Method.invoke(Method.java:511)
11-12 13:42:32.465: E/AndroidRuntime(738):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
11-12 13:42:32.465: E/AndroidRuntime(738):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
11-12 13:42:32.465: E/AndroidRuntime(738):  at dalvik.system.NativeStart.main(Native Method)
11-12 13:42:32.465: E/AndroidRuntime(738): Caused by: android.os.NetworkOnMainThreadException
11-12 13:42:32.465: E/AndroidRuntime(738):  at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1117)
11-12 13:42:32.465: E/AndroidRuntime(738):  at libcore.io.BlockGuardOs.connect(BlockGuardOs.java:84)
11-12 13:42:32.465: E/AndroidRuntime(738):  at libcore.io.IoBridge.connectErrno(IoBridge.java:127)
11-12 13:42:32.465: E/AndroidRuntime(738):  at libcore.io.IoBridge.connect(IoBridge.java:112)
11-12 13:42:32.465: E/AndroidRuntime(738):  at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:192)
11-12 13:42:32.465: E/AndroidRuntime(738):  at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:172)
11-12 13:42:32.465: E/AndroidRuntime(738):  at java.net.Socket.startupSocket(Socket.java:566)
11-12 13:42:32.465: E/AndroidRuntime(738):  at java.net.Socket.tryAllAddresses(Socket.java:127)
11-12 13:42:32.465: E/AndroidRuntime(738):  at java.net.Socket.<init>(Socket.java:177)
11-12 13:42:32.465: E/AndroidRuntime(738):  at java.net.Socket.<init>(Socket.java:149)
11-12 13:42:32.465: E/AndroidRuntime(738):  at com.mesger.TcpClient.runTcpClient(TcpClient.java:32)
11-12 13:42:32.465: E/AndroidRuntime(738):  at com.mesger.TcpClient.onCreate(TcpClient.java:25)
11-12 13:42:32.465: E/AndroidRuntime(738):  at android.app.Activity.performCreate(Activity.java:5008)
11-12 13:42:32.465: E/AndroidRuntime(738):  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1079)
11-12 13:42:32.465: E/AndroidRuntime(738):  at     android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2023)
11-12 13:42:32.465: E/AndroidRuntime(738):  ... 11 more

Answer 1

你不应该从主线程接触网络。 为网络操作实现 AsyncTask。

   private class MyInnerClass extends AsyncTask<String, Void, String> {
       @Override
       protected void onPreExecute() {
       super.onPreExecute();

       }

       @Override
       protected String doInBackground(String params) {

       return "Done";
       }

       @Override
       protected void onPostExecute(String result) {
       super.onPostExecute(result);
       }
   }

调用 new MyInnerClass().execute();从你的主 Activity 和 android 将自动调用 onPreExecute() 在你的网络访问之前在这个方法中做任何你想做的事情。

Android 将调用 doInBackground
你是否在 doInBackground() 中与网络相关的东西，完成后它会自动调用 onPostExecute() 并且结果将作为参数传递给这个方法。

Answer 2

Caused by: android.os.NetworkOnMainThreadException

您正试图在主线程上执行一个可能很慢的网络操作，这在 Android 3.0+ 中成为了一个致命的异常。只需使用 AsyncTask 或 Loader 将 runTcpClient() 移动到新线程即可。

这是一个示例：How to fix android.os.NetworkOnMainThreadException?。

---

试试这个：

class TcpClientTask extends AsyncTask<Void, Void, Void> {
    private static final int TCP_SERVER_PORT = 1234;
    private boolean error = false;

    protected Void doInBackground(Void... arg0) {
        try {
            Socket s = new Socket("10.0.2.2", TCP_SERVER_PORT);
            BufferedReader in = new BufferedReader(new InputStreamReader(s.getInputStream()));
            BufferedWriter out = new BufferedWriter(new OutputStreamWriter(s.getOutputStream()));
            //send output msg
            String outMsg = "TCP connecting to " + TCP_SERVER_PORT + System.getProperty("line.separator"); 
            out.write(outMsg);
            out.flush();
            Log.i("TcpClient", "sent: " + outMsg);
            //accept server response
            String inMsg = in.readLine() + System.getProperty("line.separator");
            Log.i("TcpClient", "received: " + inMsg);
            //close connection
            s.close();
        } catch (UnknownHostException e) {
            error = true;
            e.printStackTrace();
        } catch (IOException e) {
            error = true;
            e.printStackTrace();
        }
        return null;
    }

    protected void onPostExecute() {
        if(error) {
            // Something bad happened
        }
        else {
            // Success
        }

    }
}

要使用它，请致电：new TcpClientTask().execute();

---

我还有 1 个问题。 String inMsg = in.readLine() + System.getProperty("line.separator"); 接收消息，我将如何设置它以每 15 毫秒获取一次，或者任何稳定的东西以继续接收数据。

我不确定您要做什么。但我注意到你只调用一次readLine()，如果你想读取多行，使用循环：

StringBuilder msg = new StringBuilder();
String line;
while((line = in.readLine()) != null) // Keep reading until the end of the file is reached
    msg.append(in.readLine()).append(System.getProperty("line.separator"));

StringBuilders 在将字符串添加在一起时会产生更少的开销，当您想要获取整个消息时，只需使用 msg.toString()。

Answer 3

尝试使用 Small Piece Of Code。但这不是一个好习惯。

    StrictMode.setThreadPolicy(new StrictMode.ThreadPolicy.Builder()
   .detectNetwork()
   .permitNetwork() //permit Network access 
   .build());

您可以使用 AsynTask 或任何线程概念。 Its May Help