无法启动活动ComponentInfo android.os.NetworkOnMainThreadException

Question

我是JSON Web服务的新手。我正在传递参数并从服务器获取数据。 找到下面的代码。

在清单中添加了互联网权限。

可以帮助我使用带参数的post方法从服务器获取数据的示例代码。

出于安全原因，我在下面更改了网址详情。

请在这里帮助我。

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.TextView;

import java.io.BufferedReader;
import java.io.DataOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        try {
            TextView textview=(TextView)findViewById(R.id.textview);
            URL url=new URL("https://XXXX.net/XXX");

            HttpURLConnection connection=(HttpURLConnection)url.openConnection();
            String urlparameters="version=1.0&apikey=isjd&src=test.shoppinglist&apiname=nen&category=all";
            connection.setRequestMethod("POST");
            connection.setRequestProperty("USER-AGENT","Mozilla/5.0");
            connection.setRequestProperty("ACCEPT-LANGUAGE","en-US,en;0.5");
            connection.setDoOutput(true);
            DataOutputStream dstream=new DataOutputStream(connection.getOutputStream());
            dstream.writeBytes(urlparameters);
            dstream.flush();
            dstream.close();

            int request_code=connection.getResponseCode();
            String output="Request URL:"+url;
            output+=System.getProperty("line.separator")+" Request Parameters:"+urlparameters;
            output+=System.getProperty("line.separator")+" RequestCOde:"+request_code;

            BufferedReader br=new BufferedReader(new InputStreamReader(connection.getInputStream()));
            String line="";
            StringBuilder ResponseOutput=new StringBuilder();

            while((line=br.readLine())!=null){
                ResponseOutput.append(line);
            }
            br.close();

            output +=System.getProperty("line.separator")+ ResponseOutput.toString();

            textview.setText(output);

        } catch (MalformedURLException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}