AsynkThread 但仍然是 NetworkOnMainThreadException

Question

我尝试在我的 android 设备和 arduino nano 之间建立连接。

我测试了 raspberry pi zero 和我的 arduino 之间的 TCP 连接，它可以正常工作并完成它应该做的事情。

现在我尝试编写 android 应用程序，但它抛出了

android.io.NetworkOnMainThreadException

我发现了一些使用 AsynkTask 来完成它的提示，但它仍然抛出这个异常。我找到了一些解决方案，但对我的情况都没有帮助（例如：将 minAPI 设置为 11）。

public class MainActivity extends AppCompatActivity {

    [...]

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        [...]

        bt1.setOnClickListener(new View.OnClickListener(){
            public void onClick(View v) {
                onBtnClick();
            }
        }
    }

    public void onBtnClick() {
        new Client().execute("0101010101");
    }



    private class Client extends AsyncTask<String, Void, String> {
        protected String doInBackground(String[] params) {
            // do above Server call here
            return "null";
        }

        protected void onPostExecute(String msg) {
            String reply ="";
            try {
                reply=sendData();
            } catch(IOException e) {
                e.printStackTrace();
                reply = "IOException: "+e;
            }
            txt1.setText(reply);
        }
        public String sendData() throws IOException{

            try {
                // send message to Arduino
                InetAddress serverAddr = InetAddress.getByName(ipAddress);
                DatagramSocket clientSocket = new DatagramSocket();

                send_data = str.getBytes();
                DatagramPacket sendPacket = new DatagramPacket(send_data, send_data.length, serverAddr, portNumber);
                clientSocket.send(sendPacket);

                // get reply
                byte[] receiveData1 = new byte[512];
                DatagramPacket receivePacket = new DatagramPacket(receiveData1, receiveData1.length);
                clientSocket.receive(receivePacket);

                String reply = new String(receiveData1);
                clientSocket.close();
                return reply;

            } catch (Exception e) {
                e.printStackTrace();
                return("Exception: "+ e);
            }
        }
    }
}

我做错了什么？感谢您的帮助。

Answer 1

onPreExecute 和 onPostExecute 方法在主线程上运行，因此，sendData 方法应该在 doInBackground 上执行

private class Client extends AsyncTask<String, Void, String> {
        protected String doInBackground(String[] params) {
            String reply ="";
            try {
                reply=sendData();
            } catch(IOException e) {
                e.printStackTrace();
                reply = "IOException: "+e;
            }
        }

        protected void onPostExecute(String msg) {
            txt1.setText(reply);
        }
        public String sendData() throws IOException{

            try {
                // send message to Arduino
                InetAddress serverAddr = InetAddress.getByName(ipAddress);
                DatagramSocket clientSocket = new DatagramSocket();

                send_data = str.getBytes();
                DatagramPacket sendPacket = new DatagramPacket(send_data, send_data.length, serverAddr, portNumber);
                clientSocket.send(sendPacket);

                // get reply
                byte[] receiveData1 = new byte[512];
                DatagramPacket receivePacket = new DatagramPacket(receiveData1, receiveData1.length);
                clientSocket.receive(receivePacket);

                String reply = new String(receiveData1);
                clientSocket.close();
                return reply;

            } catch (Exception e) {
                e.printStackTrace();
                return("Exception: "+ e);
            }
        }
    }

AsynkThread 但仍然是 NetworkOnMainThreadException

AsynkThread but still NetworkOnMainThreadException

android

android-asynctask

networkonmainthread