如何从doinbackground获取结果并在onpostexcute中使用，以及如何将onpostexecute的值或结果发送到另一个活动？

Question

我可以从我的Android应用程序将值注册到服务器。注册成功时，服务器会自动发送json响应，但我无法接收响应并在另一个活动中显示响应。例如，继承我的主要活动：

主要活动：

import android.content.Intent;
import android.os.AsyncTask;
import android.support.v7.app.AlertDialog;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.Writer;
import java.io.InputStream;

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import java.net.ResponseCache;


import java.net.HttpURLConnection;
import java.net.URL;
import java.io.IOException;

public class MainActivity extends AppCompatActivity {

    EditText emailview, numberview, pwview;
    Button registerview;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        emailview = (EditText) findViewById(R.id.et1);
        numberview = (EditText) findViewById(R.id.et2);
        pwview = (EditText) findViewById(R.id.et3);
        registerview = (Button) findViewById(R.id.btn1);
    }

    public void hit(View v) {
        String email = emailview.getText().toString();
        String contact = numberview.getText().toString();
        String pw = pwview.getText().toString();
        JSONObject a = new JSONObject();

        try {
            a.put("mail", email);
            a.put("num", contact);
            a.put("pass", pw);

        } catch (JSONException e) {
            e.printStackTrace();
        }
        if (a.length() > 0) {
            new SendJsonDataToServer().execute(String.valueOf(a));
        }
    }

    class  SendJsonDataToServer extends AsyncTask<String, String, String> {

        @Override
        protected String doInBackground(String... params) {

            String JsonResponse = null;
            String JsonDATA = params[0];
            HttpURLConnection urlConnection = null;
            BufferedReader reader = null;
            try {
                URL url = new URL("example.com");
                urlConnection = (HttpURLConnection) url.openConnection();
                urlConnection.setDoOutput(true);
                // is output buffer writter
                urlConnection.setRequestMethod("POST");
                urlConnection.setRequestProperty("Content-Type", "application/json");
                urlConnection.setRequestProperty("Accept", "application/json");
//set headers and method
                Writer writer = new BufferedWriter(new OutputStreamWriter(urlConnection.getOutputStream(), "UTF-8"));
                writer.write(JsonDATA);
// json data
                writer.close();
                InputStream inputStream = urlConnection.getInputStream();
//input stream
                StringBuffer buffer = new StringBuffer();
                if (inputStream == null) {
                    // Nothing to do.
                    return null;
                }
                reader = new BufferedReader(new InputStreamReader(inputStream));

                String inputLine;
                while ((inputLine = reader.readLine()) != null)
                    buffer.append(inputLine + "\n");
                if (buffer.length() == 0) {
                    // Stream was empty. No point in parsing.
                    return null;
                }
                JsonResponse = buffer.toString();
//response data
                Log.i("o/p:", JsonResponse);
                try {
//send to post execute
                    return JsonResponse;
                } catch (Exception e){

                }
                return null;

            } catch (IOException e) {
                e.printStackTrace();
            } finally {
                if (urlConnection != null) {
                    urlConnection.disconnect();
                }
                if (reader != null) {
                    try {
                        reader.close();
                    } catch (final IOException e) {
                        Log.e("wtf", "Error closing stream", e);
                    }
                }
            }
            return null;
        }




    @Override
    protected void onPostExecute(String s) {
        Log.i("Here it is:",s);
        Log.e("Here it is:",s);
        try {
            JSONObject jsonResponse = new JSONObject(s);
            int status= jsonResponse.getInt("status");
            String message =jsonResponse.getString("message");

            JSONArray arr = jsonResponse.getJSONArray("data");

                if ( status==1){
                    for (int i=0;i<arr.length();i++) {
                        JSONObject lol = arr.getJSONObject(i);

                        String token = lol.getString("token");
                        String email = lol.getString("email");


                        Intent intent = new Intent(MainActivity.this, UserAreaActivity.class);
                        intent.putExtra("message", message);
                        intent.putExtra("token", token);
                        intent.putExtra("email", email);

                        startActivity(intent);


                    }}


            else {

                AlertDialog.Builder builder=new AlertDialog.Builder(MainActivity.this);
                builder.setMessage("Registration failed").setNegativeButton("retry",null)
                        .create()
                        .show();
            }




        } catch (JSONException e) {

            e.printStackTrace();
        }



    }}
}

这是显示响应的责任活动

UserAreaActivity：

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

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


public class UserAreaActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_user_area);
        setContentView(R.layout.activity_user_area);
        final TextView tar =(TextView)findViewById(R.id.tv1);
        final TextView zar =(TextView)findViewById(R.id.tv2);
        final TextView par =(TextView)findViewById(R.id.tv3);

        Intent intent=getIntent();
        String message=intent.getStringExtra("message");
        String token =intent.getStringExtra("token");
        String email=intent.getStringExtra("email");

        tar.setText(message);
        zar.setText(token);
        par.setText(email);
    }
}