问我只想通过android发送get请求，但是它不起作用，我的代码如下所示，

EN

  public void sendGET(String GET_URL) throws IOException {
    try {
        URL obj = new URL(GET_URL);
        HttpURLConnection con = (HttpURLConnection) obj.openConnection();
        con.setRequestMethod("GET");
        con.setRequestProperty("User-Agent", USER_AGENT);
        int responseCode = con.getResponseCode();
    }
    catch (IOException e) {
        e.printStackTrace();
    }
}

这是我为get请求编写的方法。在我的例子中，GET_URL是一个字符串，它的值是GET_URL=192.168.4.1?value=1。我在点击按钮时调用了这个方法，但是它在android中不工作，而在java中，它工作得很完美。注意:我的apk编译时没有任何错误，而且它也在运行，但是get请求不起作用。按钮代码如下，

    led1on.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            try{
                sendGET("http://192.168.4.1/?linker=1");
                Toast.makeText(getApplicationContext(),
                        "Led1 ON Clicked!", Toast.LENGTH_SHORT).show();
            }
            catch (IOException e){

            }
        }
    });

崩溃日志在这里： 07-29 16:10:07.352 3459-3459/com.example.samiullah.esp 8266 E/AndroidRuntime:致命异常:主要进程: com.example.samiullah.esp8266，PID: 3459 android.os.NetworkOnMainThreadException at android.os.NetworkOnMainThreadException在libcore.io.BlockGuardOs.connect(BlockGuardOs.java:110) at libcore.io.IoBridge.connectErrno(IoBridge.java:137)在libcore.io.IoBridge.connect(IoBridge.java:122) at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:183)java.net.PlainSocketImpl.connect(PlainSocketImpl.java:452) at java.net.Socket.connect(Socket.java:884).android.okhttp.internal.Platform.connectSocket(Platform.java:117) at com.android.okhttp.internal.http.SocketConnector.connectRawSocket(SocketConnector.java:160)在com.android.okhttp.internal.http.SocketConnector.connectCleartext(SocketConnector.java:67) at com.android.okhttp.Connection.connect(Connection.java:152)在com.android.okhttp.Connection.connectAndSetOwner(Connection.java:185) at com.android.okhttp.OkHttpClient$1.connectAndSetOwner(OkHttpClient.java:128) at com.android.okhttp.internal.http.HttpEngine.nextConnection(HttpEngine.java:341) at com.android.okhttp.internal.http.HttpEngine.connect(HttpEngine.java:330)在com.android.okhttp.internal.http.HttpEngine.sendRequest(HttpEngine.java:248) at com.android.okhttp.internal.huc.HttpURLConnectionImpl.execute(HttpURLConnectionImpl.java:433)在com.android.okhttp.internal.huc.HttpURLConnectionImpl.getResponse(HttpURLConnectionImpl.java:384) at com.android.okhttp.internal.huc.HttpURLConnectionImpl.getResponseCode(HttpURLConnectionImpl.java:497)在com.example.samiullah.esp8266.MainActivity.sendGET(MainActivity.java:110) at com.example.samiullah.esp8266.MainActivity$1.onClick(MainActivity.java:29)在android.view.View.performClick(View.java:5198) at android.view.View$PerformClick.run(View.java:21147)在android.os.Handler.handleCallback(Handler.java:739) at android.os.Handler.dispatchMessage(Handler.java:95) at android.os.Looper.loop(Looper.java:148)在android.app.ActivityThread.main(ActivityThread.java:5417) at java.lang.reflect.Method.invoke(原生方法)在com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616) 07-29 :10:09.956 3459-3459/com.example.samiullah.esp 8266 I/Process:发送信号。PID: 3459 SIG: 9