java - Android套接字客户端不工作

Question

我尝试像这样创建一个到 python 服务器的套接字客户端连接，但它抛出一个错误。这是通过一个按钮触发的，该按钮有效。服务器在 RPi 上运行，但这不是问题，因为 Python 客户端可以在我的 PC 上运行。

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);
    }

堆栈跟踪:

    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

您不能在主 UI 线程上执行任何长时间处理，这是为了避免操作失败时应用程序崩溃

尝试创建新线程并在其中完成您的工作，如果您想将任何结果传递给您无法使用的 UI

View.Post()

或者

 context.runOnUiThread()

这是您可以执行的操作的示例，或者您可以改用 asynctask

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();