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。

我测试了树莓派零和我的 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 执行此操作的提示，但它仍然会引发此异常。我找到了一些解决方案，但在我的情况下都没有帮助（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，所以 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);
            }
        }
    }