Android socket客户端无法工作

Question

我尝试创建一个套接字客户端连接到一个Python服务器，结果却出现了错误。这个连接是通过一个按钮触发的，按钮是可以正常工作的。服务器运行在树莓派上，但这不是问题，因为我在我的电脑上用Python客户端连接是没问题的。

try {

        Socket s = new Socket("192.168.178.43", 24069);
        InputStreamReader streamReader = new InputStreamReader(s.getInputStream());
        BufferedReader reader = new BufferedReader(streamReader);

        String advice = reader.readLine();
        reader.close();

    } catch (UnknownHostException e) {
        System.err.println("Unknown Host.");
        // System.exit(1);
    } catch (IOException e) {
        System.err.println("Couldn't get I/O for "
                + "the connection.");
        System.err.println(e);
        //  System.exit(1);
    }

错误追踪信息：

    java.lang.IllegalStateException: Could not execute method of the activity
            at android.view.View$1.onClick(View.java:3823)
            at android.view.View.performClick(View.java:4438)
            at android.view.View$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:5017)
            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.view.View$1.onClick(View.java:3818)
            at android.view.View.performClick(View.java:4438)
            at android.view.View$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:5017)
            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:127)
            at libcore.io.IoBridge.connect(IoBridge.java:112)
            at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:192)
            at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:172)
            at java.net.Socket.startupSocket(Socket.java:567)
            at java.net.Socket.tryAllAddresses(Socket.java:128)
            at java.net.Socket.<init>(Socket.java:178)
            at java.net.Socket.<init>(Socket.java:150)
            at com.example.app.MainActivity.sendMessage(MainActivity.java:65)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:515)
            at android.view.View$1.onClick(View.java:3818)
            at android.view.View.performClick(View.java:4438)
at android.view.View$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:5017)
            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)

Answer 1

你不能在主界面线程上进行长时间的操作，原因是为了避免你的应用崩溃，如果你的操作失败了。

你应该尝试创建一个新的线程，在里面完成你的工作。如果你想把结果传递给界面，你不能直接使用

View.Post()

或者

 context.runOnUiThread()

这是你可以做的一个例子，或者你也可以使用asynctask来代替。

new Thread(new Runnable() {
        public void run() {
           try {

        Socket s = new Socket("192.168.178.43", 24069);
        InputStreamReader streamReader = new InputStreamReader(s.getInputStream());
        BufferedReader reader = new BufferedReader(streamReader);

        String advice = reader.readLine();
        reader.close();

    } catch (UnknownHostException e) {
        System.err.println("Unknown Host.");
        // System.exit(1);
    } catch (IOException e) {
        System.err.println("Couldn't get I/O for "
                + "the connection.");
        System.err.println(e);
        //  System.exit(1);
    }

        }
    }).start();