Android套接字连接麻烦

Question

I made a client(android (java))-server(node.js) application.

The problem is when I use AVD emulator (with 10.0.2.2 or exteranl IP) to test my programm, ewerything works well, but when I try to do the same with phone or another emulator (genimotion, nox, bluestacks) it I can`t connect at all.

Users permisson to use internet and wi-fi is required. The code of connect function is:

    public void Connect(String Host, int Port)
{
    try
    {
        System.out.println(Handlers.isEmpty());
        if (Handlers.isEmpty())
            throw new NullPointerException ("No handlers");

        if (Socket != null && Socket.isConnected())
            Socket.close();

        InetAddress IpAddress = InetAddress.getByName(Host);
        Address = new InetSocketAddress(IpAddress, Port);
        Socket = new Socket();
        Socket.setSoTimeout(1000);
        Socket.connect(Address, 1500);
        InputStream = new BufferedReader (new InputStreamReader(Socket.getInputStream()));
        OutputStream = new PrintWriter (Socket.getOutputStream());
        RThread = new ReadSocketThread(InputStream, Handlers, SearchName);
        ReadSocket = new Thread(RThread);
        ReadSocket.start();
    }
    catch (IOException e)
    {
        e.printStackTrace();
    }

}

and the console said:

E/AndroidRuntime: FATAL EXCEPTION: main
              Process: bobko.alexandr.consultant, PID: 1599
              java.lang.IllegalStateException: Could not execute method for android:onClick
                  at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:293)
                  at android.view.View.performClick(View.java:4438)
                  at android.view.View$PerformClick.run(View.java:18422)
                  at android.os.Handler.handleCallback(Handler.java:733)
                  at android.os.Handler.dispatchMessage(Handler.java:95)
                  at android.os.Looper.loop(Looper.java:136)
                  at android.app.ActivityThread.main(ActivityThread.java:5045)
                  at java.lang.reflect.Method.invokeNative(Native Method)
                  at java.lang.reflect.Method.invoke(Method.java:515)
                  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
                  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
                  at dalvik.system.NativeStart.main(Native Method)
               Caused by: java.lang.reflect.InvocationTargetException
                  at java.lang.reflect.Method.invokeNative(Native Method)
                  at java.lang.reflect.Method.invoke(Method.java:515)
                  at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:288)
                  at android.view.View.performClick(View.java:4438) 
                  at android.view.View$PerformClick.run(View.java:18422) 
                  at android.os.Handler.handleCallback(Handler.java:733) 
                  at android.os.Handler.dispatchMessage(Handler.java:95) 
                  at android.os.Looper.loop(Looper.java:136) 
                  at android.app.ActivityThread.main(ActivityThread.java:5045) 
                  at java.lang.reflect.Method.invokeNative(Native Method) 
                  at java.lang.reflect.Method.invoke(Method.java:515) 
                  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779) 
                  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595) 
                  at dalvik.system.NativeStart.main(Native Method) 
               Caused by: android.os.NetworkOnMainThreadException
                  at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1145)
                  at libcore.io.BlockGuardOs.connect(BlockGuardOs.java:84)
                  at libcore.io.IoBridge.connectErrno(IoBridge.java:144)
                  at libcore.io.IoBridge.connect(IoBridge.java:112)
                  at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:192)
                  at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:459)
                  at java.net.Socket.connect(Socket.java:843)
                  at bobko.alexandr.consultant.STAPLibrary.STAPLibraryMain.Connect(STAPLibraryMain.java:53)
                  at bobko.alexandr.consultant.MainActivity.Create(MainActivity.java:29)
                  at java.lang.reflect.Method.invokeNative(Native Method) 
                  at java.lang.reflect.Method.invoke(Method.java:515) 
                  at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:288) 
                  at android.view.View.performClick(View.java:4438) 
                  at android.view.View$PerformClick.run(View.java:18422) 
                  at android.os.Handler.handleCallback(Handler.java:733) 
                  at android.os.Handler.dispatchMessage(Handler.java:95) 
                  at android.os.Looper.loop(Looper.java:136) 
                  at android.app.ActivityThread.main(ActivityThread.java:5045) 
                  at java.lang.reflect.Method.invokeNative(Native Method) 
                  at java.lang.reflect.Method.invoke(Method.java:515) 
                  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779) 
                  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595) 
                  at dalvik.system.NativeStart.main(Native Method) 

Application terminated.

Answer 1

As you are performing network operation in main thread NetworkOnMainThreadException is thrown. That's why you are not able to connect.

You should either wrap the code that connects to network inside a AsyncTask or use library like Retrofit . Simply, network operation must be run in a thread other than main UI thread.