Android How to - Consume Json Services

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JSON is a lightweight data-interchange format that is easy for humans to read and write.

The following lines of code show what a JSON message looks like:

[
      {
          "Id":"1",
          "Date":"2014-03 14",
          "Time":"12:19:47"
      },
      {
          "Id":"32",
          "Date":"2008-03-14",
          "Time":"22:43:09"
      }
]

The information is represented as a collection of key/value pairs. Each key/value pair is grouped into an ordered list of objects.

The following code shows how to Consume Json Services.

Example

AndroidManifest.xml file:

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.java2s.JSON"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk android:minSdkVersion="14" />
    <uses-permission android:name="android.permission.INTERNET"/>

    <application
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name" >
        <activity
            android:label="@string/app_name"
            android:name=".JSONActivity" >
            <intent-filter >
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

Main Activity Java code

package com.java2s.myapplication3.app;
//from   ww w .  ja  v  a 2s .c  o m

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.StatusLine;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient;
import org.json.JSONArray;
import org.json.JSONObject;

import android.app.Activity;
import android.os.AsyncTask;
import android.os.Bundle;
import android.util.Log;
import android.widget.Toast;

public class MainActivity extends Activity  {

    public String readJSONFeed(String URL) {
        StringBuilder stringBuilder = new StringBuilder();
        HttpClient client = new DefaultHttpClient();
        HttpGet httpGet = new HttpGet(URL);
        try {
            HttpResponse response = client.execute(httpGet);
            StatusLine statusLine = response.getStatusLine();
            int statusCode = statusLine.getStatusCode();
            if (statusCode == 200) {
                HttpEntity entity = response.getEntity();
                InputStream content = entity.getContent();
                BufferedReader reader = new BufferedReader(
                        new InputStreamReader(content));
                String line;
                while ((line = reader.readLine()) != null) {
                    stringBuilder.append(line);
                }
            } else {
                Log.e("JSON", "Failed to download file");
            }
        } catch (ClientProtocolException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return stringBuilder.toString();
    }

    private class ReadJSONFeedTask extends AsyncTask<String, Void, String> {
        protected String doInBackground(String... urls) {
            return readJSONFeed(urls[0]);
        }

        protected void onPostExecute(String result) {
            try {
                JSONArray jsonArray = new JSONArray(result);
                Log.i("JSON", "Number of surveys in feed: " +
                        jsonArray.length());

                //---print out the content of the json feed---
                for (int i = 0; i < jsonArray.length(); i++) {
                    JSONObject jsonObject = jsonArray.getJSONObject(i);
                    Toast.makeText (getBaseContext(), jsonObject.getString("appeId") +
                                    " - " + jsonObject.getString("inputTime"),
                            Toast.LENGTH_SHORT).show();
                }
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        new ReadJSONFeedTask().execute(
                "http://your address.html");
    }
}

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