如何在android中解析JSON响应？

Question

I am having JSON response like this.

{"Fullname":" Prasad","vault_no":"12745"}.

How to convert this to string in android.This is my Android class file.

Register.class

package com.example.test;

import android.app.Activity;
import android.app.ProgressDialog;
import android.content.Intent;
import android.os.AsyncTask;
import android.os.Bundle;
import android.text.TextUtils;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Spinner;
import android.widget.TextView;
import android.widget.Toast;

import org.json.JSONObject;

import java.util.HashMap;


public class Register extends Activity implements View.OnClickListener{


    private static final int[] CategoryCode = new int[]{0,1,2,3}; // array to save Salutation code
    private static final String[] Category = new String[]{"Cartegory","Male","Female","Company"}; // array to show Salutation

    private static final int[] SalutationCode = new int[]{0,1,2,3,4,5,6,7,8,9,0}; // array to save Salutation code
    private static final String[] Salutation = new String[]{"Salutation","Mr","Ms","SME(small scale)",
            "SU(start-up's)","SB(service based)","CA(charted accountant)","DR(doctor)",
    "LC(large scale)","Others", "None"};

    private static final int[] CountryCode = new int[]{0,91}; // array to save Country code
    private static final String[] Country = new String[]{"Country","India"}; // array to show Country name.

    private static final int[] CityCode = new int[]{0,1}; // array to save City code
    private static final String[] City = new String[]{"City","Bangalore"}; // array to show City list

    private static final int[] StateCode = new int[]{0,1}; // array to save State code
    private static final String[] State = new String[]{"State","Karnataka"}; // array to show State list

    int selectedAreaCode;
    private Spinner spin;
    private Spinner spin0;
    private Spinner spin1;
    private Spinner spin2;
    private Spinner spin3;
    private EditText editTextFname;
    private EditText editTextLname;
    private EditText editTextDob;
    private EditText editTextPob;
    private EditText editTextMobile;
    private EditText editTextEmail;
    private EditText editTextPin;
    private Button register;
    private Button login;

    private static final String REGISTER_URL = "http://oursite/insert-db(1).php";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        getActionBar().setDisplayShowTitleEnabled(false);
        setContentView(R.layout.activity_register_page);

        spin = (Spinner)findViewById(R.id.spinner1);
        spin0 = (Spinner)findViewById(R.id.spinner01);
        spin1 = (Spinner)findViewById(R.id.spinner2);
        spin2 = (Spinner)findViewById(R.id.spinner3);
        spin3 = (Spinner)findViewById(R.id.spinner4);
        editTextFname = (EditText) findViewById(R.id.editTextFname);
        editTextLname = (EditText) findViewById(R.id.editTextLname);
        editTextDob = (EditText)findViewById(R.id.editTextDob);
        editTextPob = (EditText)findViewById(R.id.editTextPob);
        editTextMobile = (EditText) findViewById(R.id.editTextMobile);
        editTextEmail = (EditText)findViewById(R.id.editTextEmail);
        editTextPin = (EditText) findViewById(R.id.editTextPin);

        register = (Button) findViewById(R.id.button);
        login = (Button) findViewById(R.id.button2);
        register.setOnClickListener(this);

        login.setOnClickListener(this);

        ArrayAdapter<String> adpt_area = new ArrayAdapter<String>(this,
                android.R.layout.simple_spinner_item, Category);
        adpt_area.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
        spin.setAdapter(adpt_area);

        ArrayAdapter<String> cat = new ArrayAdapter<String>(this,
                android.R.layout.simple_spinner_item, Salutation);
        cat.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
        spin0.setAdapter(cat);

        ArrayAdapter<String> adpt_country = new ArrayAdapter<String>(this,
                android.R.layout.simple_spinner_item, Country);
        adpt_country.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
        spin1.setAdapter(adpt_country);

        ArrayAdapter<String> adpt_city = new ArrayAdapter<String>(this,
                android.R.layout.simple_spinner_item, City);
        adpt_city.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
        spin2.setAdapter(adpt_city);

        ArrayAdapter<String> adpt_state = new ArrayAdapter<String>(this,
                android.R.layout.simple_spinner_item, State);
        adpt_state.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
        spin3.setAdapter(adpt_state);


    }

    @Override
    public void onClick(View v) {
        if(v == register){
            registerUser();
        }
        if(v == login){
            startActivity(new Intent(this,LoginPage.class));
        }
    }

    private void registerUser() {


        String fname = editTextFname.getText().toString();

        if(TextUtils.isEmpty(fname)) {
            editTextFname.setError("please enter first name");
            return;
         }

        String lname = editTextLname.getText().toString();

        if(TextUtils.isEmpty(lname)) {
            editTextLname.setError("please enter last name");
            return;
         }

        String dob = editTextDob.getText().toString();

        if(TextUtils.isEmpty(dob)) {
            editTextDob.setError("enter date of birth");
            return;
         }

        String pob = editTextPob.getText().toString();

        if(TextUtils.isEmpty(pob))  {
            editTextPob.setError("enter the place of birth");
            return;
        }

        String mobile = editTextMobile.getText().toString();

        if(TextUtils.isEmpty(mobile)) {
            editTextMobile.setError("please enter mobile no");
            return;
         }

        String email = editTextEmail.getText().toString();
        if(TextUtils.isEmpty(email)) {
            editTextEmail.setError("please enter the email id");
            return;

        }

        String pin = editTextPin.getText().toString();

        if(TextUtils.isEmpty(pin)) {
            editTextPin.setError("please enter pin no");
            return;
         }

         int selectedPosition = spin.getSelectedItemPosition();
         // get area code based on value selected in spinner
         String category = String.valueOf(CategoryCode[selectedPosition]);

        int selectedPosition0 = spin0.getSelectedItemPosition();
        // get area code based on value selected in spinner
        String salutation = String.valueOf(SalutationCode[selectedPosition0]);

         int selectedPosition1 = spin1.getSelectedItemPosition();
         // get area code based on value selected in spinner
         String country = String.valueOf(CountryCode[selectedPosition1]);

         int selectedPosition2 = spin2.getSelectedItemPosition();
         // get area code based on value selected in spinner
         String state = String.valueOf(StateCode[selectedPosition2]);

         int selectedPosition3 = spin3.getSelectedItemPosition();
         // get area code based on value selected in spinner
         String city = String.valueOf(CityCode[selectedPosition3]);


        register(salutation,category,fname,lname,dob,pob,mobile,email,country,state,city,pin);
    }

    private void register(String salutation, String category, String fname, String lname,String dob,String pob,String mobile, String  email,String country, String state, String city, String pin) {
        class RegisterUser extends AsyncTask<String, Void, String>{
            ProgressDialog loading;
            //RegisterUserClass ruc = new RegisterUserClass();
            RequestHandler ruc = new RequestHandler();

            @Override
            protected void onPreExecute() {
                super.onPreExecute();
                loading = ProgressDialog.show(Register.this, "Please Wait",null, true, true);
            }

            @Override
            protected void onPostExecute(String s) {
                super.onPostExecute(s);
                loading.dismiss();
                Toast.makeText(getApplicationContext(),"Successfully Registered..!!",Toast.LENGTH_LONG).show();
                editTextFname.setText("");
                editTextLname.setText("");
                editTextDob.setText("");
                editTextPob.setText("");
                editTextMobile.setText("");
                editTextEmail.setText("");
                editTextPin.setText("");

                Intent i = new Intent(Register.this,UserProfile.class);
                i.putExtra("s", s);
                startActivity(i);
            }

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

                HashMap<String, String> data = new HashMap<String,String>();
                data.put("salutation",params[0]);
                data.put("category",params[1]);
                data.put("fname",params[2]);
                data.put("lname",params[3]);
                data.put("dob",params[4]);
                data.put("pob",params[5]);
                data.put("mobile",params[6]);
                data.put("email", params[7]);
                data.put("country",params[8]);
                data.put("state",params[9]);
                data.put("city",params[10]);
                data.put("pin",params[11]);


                String result = ruc.sendPostRequest(REGISTER_URL,data);

                return  result;
            }
        }

        RegisterUser ru = new RegisterUser();
        ru.execute(salutation,category,fname,lname,dob,pob,mobile,email,country,state,city,pin);
    }
}

The String " s " in onPostExecute(String s) will hold the JSON value. How to convert it to string and pass it to next page?

RequestHandler.class

package com.example.test;

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.UnsupportedEncodingException;
import java.net.HttpURLConnection;
import java.net.URL;
import java.net.URLEncoder;
import java.util.HashMap;
import java.util.Map;

import javax.net.ssl.HttpsURLConnection;

public class RequestHandler {

    public String sendPostRequest(String requestURL,
                                  HashMap<String, String> postDataParams) {

        URL url;

        StringBuilder sb = new StringBuilder();
        try {
            url = new URL(requestURL);

            HttpURLConnection conn = (HttpURLConnection) url.openConnection();
            conn.setReadTimeout(15000);
            conn.setConnectTimeout(15000);
            conn.setRequestMethod("POST");
            conn.setDoInput(true);
            conn.setDoOutput(true);


            OutputStream os = conn.getOutputStream();
            BufferedWriter writer = new BufferedWriter(
                    new OutputStreamWriter(os, "UTF-8"));
            writer.write(getPostDataString(postDataParams));

            writer.flush();
            writer.close();
            os.close();
            int responseCode = conn.getResponseCode();

            if (responseCode == HttpsURLConnection.HTTP_OK) {
                BufferedReader br = new BufferedReader(new InputStreamReader(conn.getInputStream()));
                sb = new StringBuilder();
                String response;
                while ((response = br.readLine()) != null){
                    sb.append(response);
                }
            }

        } catch (Exception e) {
            e.printStackTrace();
        }
        return sb.toString();
    }

    private String getPostDataString(HashMap<String, String> params) throws UnsupportedEncodingException {
        StringBuilder result = new StringBuilder();
        boolean first = true;
        for (Map.Entry<String, String> entry : params.entrySet()) {
            if (first)
                first = false;
            else
                result.append("&");

            result.append(URLEncoder.encode(entry.getKey(), "UTF-8"));
            result.append("=");
            result.append(URLEncoder.encode(entry.getValue(), "UTF-8"));
        }

        return result.toString();
    }
}

Answer 1

Create A DTO class like below

public class JsonResponseFromserver {

    @SerializedName("Fullname")
    public boolean fullname;

    @SerializedName("vault_no")
    public String vault_no;
}

Change your AsynTask To:

class RegisterUser extends AsyncTask<String, Integer, JsonResponseFromserver>{
            ProgressDialog loading;
            //RegisterUserClass ruc = new RegisterUserClass();
            RequestHandler ruc = new RequestHandler();

            @Override
            protected void onPreExecute() {
                super.onPreExecute();
                loading = ProgressDialog.show(Register.this, "Please Wait",null, true, true);
            }

            @Override
            protected void onPostExecute(JsonResponseFromserver s) {
                super.onPostExecute(s);
                loading.dismiss();
                Toast.makeText(getApplicationContext(),"Successfully Registered..!!",Toast.LENGTH_LONG).show();
                editTextFname.setText("");
                editTextLname.setText("");
                editTextDob.setText("");
                editTextPob.setText("");
                editTextMobile.setText("");
                editTextEmail.setText("");
                editTextPin.setText("");

                Intent i = new Intent(Register.this,UserProfile.class);
                i.putExtra("s", s.fullname);
                startActivity(i);
            }

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

                HashMap<String, String> data = new HashMap<String,String>();
                data.put("salutation",params[0]);
                data.put("category",params[1]);
                data.put("fname",params[2]);
                data.put("lname",params[3]);
                data.put("dob",params[4]);
                data.put("pob",params[5]);
                data.put("mobile",params[6]);
                data.put("email", params[7]);
                data.put("country",params[8]);
                data.put("state",params[9]);
                data.put("city",params[10]);
                data.put("pin",params[11]);


                JsonResponseFromserver result = ruc.sendPostRequest(REGISTER_URL,data);

                return  result;
            }
        }

And..

if (responseCode == HttpsURLConnection.HTTP_OK) {
                BufferedReader br = new BufferedReader(new InputStreamReader(conn.getInputStream()));
                sb = new StringBuilder();
                String response;
                while ((response = br.readLine()) != null){
                    sb.append(response);
                }
            }

        } catch (Exception e) {
            e.printStackTrace();
        }
       return new Gson().fromJson(sb.toString(),JsonResponseFromserver.class);
    }

Answer 2

You can make use of the inbuilt JSONObject for this.

JSONObject jsonObject = new JSONObject(s);
String fullName = jsonObject.getString("Fullname");