Making a Background Service and Parsing some JSON from URL

Making a background service is really easy. We just need to extend Service() class in any of our class to make it a service. Implement its method and you are done. And just one more thing, don't forget to call it from your main activity using Intent.

In this post, the JParsingInBackground class which extends Service will continuously run in background and will hit the URL and fetch JSON data every 60 sec.

MainActivity.java

package com.example.jsoninbackground;

import android.app.Activity;

import android.content.Intent;

import android.os.Bundle;

import android.util.Log;

public class MainActivity extends Activity {

;

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

               // to invoke service the first time

Intent mServiceIntent = new Intent(this, JparsingInBackground.class);

this.startService(mServiceIntent);

Log.e("Activity started","Running activity");

}

}

JparsingInBackground.java

package com.example.jsoninbackground;

import java.util.ArrayList;

import java.util.HashMap;

import java.util.List;

import org.apache.http.NameValuePair;

import org.apache.http.message.BasicNameValuePair;

import org.json.JSONArray;

import org.json.JSONException;

import org.json.JSONObject;

import android.annotation.TargetApi;

import android.app.Notification;

import android.app.NotificationManager;

import android.app.PendingIntent;

import android.app.Service;

import android.app.TaskStackBuilder;

import android.content.Context;

import android.content.Intent;

import android.os.AsyncTask;

import android.os.Build;

import android.os.Handler;

import android.os.IBinder;

import android.support.v4.app.NotificationCompat;

import android.util.Log;

public class JparsingInBackground extends Service {

JSONParser jsonParser;

JSONObject jsono;

JSONArray category = null;

List<NameValuePair> params = new ArrayList<NameValuePair>();

String str;

private Handler mHandler = new Handler();

private NotificationManager mNotificationManager;

private int numMessages = 0;

private static String url = "http://stringr.in/application/DB_fetchCategoryFromDB.php";

private static final String TAG_CATEGORY = "category";

private static final String TAG_CATEGORY_ID = "category_id";

private static final String TAG = "tag";

private static final String TAG_NAME = "name";

       

         // makes the service run infinitely

private void ping() {

try {

new GetContacts().execute();

} catch (Exception e) {

Log.e("Error", "In onStartCommand");

e.printStackTrace();

}

scheduleNext();

}

private void scheduleNext() {

mHandler.postDelayed(new Runnable() {

public void run() {

ping();

}

}, 60000);

}

public int onStartCommand(Intent intent, int x, int y) {

mHandler = new android.os.Handler();

ping();

return START_STICKY;

}

@Override

public IBinder onBind(Intent arg0) {

Log.e("IBinder started", "Running finely");

return null;

}

        // Async task to fetch JSON

private class GetContacts extends AsyncTask<Void, Void, Void> {

@Override

protected void onPreExecute() {

super.onPreExecute();

}

@Override

protected Void doInBackground(Void... arg0) {

try {

jsonParser = new JSONParser();

params.add(new BasicNameValuePair("bid", "1"));

//json object

jsono = jsonParser.getJSONFromUrl(url, params);

category = jsono.getJSONArray(TAG_CATEGORY);

for (int i = 0; i <category.length(); i++) {

JSONObject c = category.getJSONObject(i);

str = c.getString("name");

Log.e("name",str);

}

} catch (Exception e) {

e.printStackTrace();

Log.e("ee", e.toString());

}

return null;

}

@Override

protected void onPostExecute(Void result) {

super.onPostExecute(result);

displayNotification(str);

}

}

       //This is a function to show notifications

@TargetApi(Build.VERSION_CODES.JELLY_BEAN)

public void displayNotification(String name) {

Log.i("Start", "notification");

/* Invoking the default notification service */

NotificationCompat.Builder mBuilder = new NotificationCompat.Builder(

getApplicationContext());

mBuilder.setSmallIcon(R.drawable.ic_launcher);

mBuilder.setContentTitle(name);

mBuilder.setContentText(name);

mBuilder.setAutoCancel(true);

mBuilder.setDefaults(Notification.DEFAULT_LIGHTS);

mBuilder.setDefaults(Notification.FLAG_AUTO_CANCEL

| Notification.FLAG_SHOW_LIGHTS);

/* Increase notification number every time a new notification arrives */

mBuilder.setNumber(++numMessages);

/* Creates an explicit intent for an Activity in your app */

Intent resultIntent = new Intent(getApplicationContext(),

MainActivity.class);

resultIntent.putExtra("name", name);

TaskStackBuilder stackBuilder = TaskStackBuilder

.create(getApplicationContext());

stackBuilder.addParentStack(MainActivity.class);

/* Adds the Intent that starts the Activity to the top of the stack */

stackBuilder.addNextIntent(resultIntent);

PendingIntent resultPendingIntent = stackBuilder.getPendingIntent(0,

PendingIntent.FLAG_UPDATE_CURRENT);

mBuilder.setContentIntent(resultPendingIntent);

mNotificationManager = (NotificationManager) getApplicationContext()

.getSystemService(Context.NOTIFICATION_SERVICE);

/* notificationID allows you to update the notification later on. */

mNotificationManager.notify(100, mBuilder.build());

mBuilder.setVibrate(null);

}

}

We also need to add service to the manifest file and add internet and some other permissions.

Manifest File

<?xml version="1.0" encoding="utf-8"?>

<manifest xmlns:android="http://schemas.android.com/apk/res/android"

    package="com.example.jsoninbackground"

    android:versionCode="1"

    android:versionName="1.0" >

    <uses-sdk

        android:minSdkVersion="10"

        android:targetSdkVersion="18" />

      

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

    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />

    <uses-permission android:name="android.permission.WAKE_LOCK" />

    

    <application

        android:allowBackup="true"

        android:icon="@drawable/ic_launcher"

        android:label="@string/app_name"

        android:theme="@style/AppTheme" >

        <activity

            android:name="com.example.jsoninbackground.MainActivity"

            android:label="@string/app_name" >

            <intent-filter>

                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />

            </intent-filter>

        </activity>

         <service

            android:name=".JparsingInBackground"

            android:exported="false" />

    </application>

</manifest>