Different Types
of Started Service:
1. Normal Service without Thread.
2. Service with Single Thread
3. Service with Multithreading
4. Service with Multithreading
(ASYNC TASK)
Normal Service Without
Thread:
1.
Create service tag in your manifest.xml
file.
2.
Implement life cycle function for your
service.
3.
Start your service from your activity and
make sure your service will stop.
Example:
Manifest.xml
For
developing any service , you need to include service tag in your manifest file.
<?xml
version="1.0" encoding="utf-8"?>
<manifest
xmlns:android="http://schemas.android.com/apk/res/android"
package="tara.service"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="15" />
<application
android:icon="@drawable/ic_launcher"
android:label="@string/app_name" >
<activity
android:name=".MyActivity"
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="MyService"></service>
</application>
</manifest>
Main.xml
Create a
button in main.xml. When you click the button, service will start.
<?xml
version="1.0" encoding="utf-8"?>
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical"
>
<Button
android:id="@+id/button1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Button" />
</LinearLayout>
MyActivity.java
public class
MyActivity extends Activity
{
Intent it = new Intent(this,
MyService.class);
public void onCreate(Bundle
savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
Button btn =
(Button)findViewById(R.id.button1);
btn.setOnClickListener(new OnClickListener()
{
public void
onClick(View v)
{
startService(it);
}
});
}
protected void onDestroy()
{
stopService(it);
}
MyService.java
public class
MyService extends Service
{
@Override
public void onCreate()
{
super.onCreate();
}
@Override
public int onStartCommand(Intent
intent, int flags, int startId)
{
return
super.onStartCommand(intent, flags, startId);
}
@Override
public void onDestroy()
{
super.onDestroy();
}
@Override
public IBinder onBind(Intent
intent)
{
return null;
}
}
Service With Single Thread:
In service with single thread, you can manually create a
thread. You need to use IntentService class, thread will be created
automatically.
1.
Create service tag in your manifest.xml
file. Provide the class name (MyService.java). It will extends from
IntentService. Then add the un-implemented method.
2.
Start your service from your activity and
make sure your service will stop.
Manifest.xml
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="tara.service"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="15" />
<application
android:icon="@drawable/ic_launcher"
android:label="@string/app_name" >
<activity
android:name=".Home"
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="MyService"></service>
</application>
</manifest>
MyService.java
public class MyService extends
IntentService
{
public MyService(String name) {
super(name);
// TODO Auto-generated constructor stub
}
@Override
protected void
onHandleIntent(Intent arg0) {
// TODO Auto-generated method stub
}
}
Here you can’t touch
UI beacause onHandleIntent() is running on different thread created by
IntentService.
Service With MultiThreading (ASYNC-TASK):
AsyncTask
has 4 operations,
which are executed by order.
1. onPreExecute() – is invoked before the execution.
2.
onPostExecute() - is invoked after the execution.
3.
doInBackground() - the main operation. Write your heavy operation here.
4.
onProgressUpdate() –
Indication to the user on progress. It is invoked every time publishProgress() is called.
AsyncTask defines 3 generic
types:
AsyncTask<{type of the input}, {type of the update unit}, {type of the
result}>
You don’t have to use all of them – simply use ‘Void’ for any of them.
Android developer website also
mentions these 4 rules regarding the AsyncTask:
§ The
task instance must be created on the UI thread.
§ execute(Params…)
must be invoked on the UI thread.
§ Do
not call onPreExecute(), onPostExecute(Result), doInBackground(Params…),
onProgressUpdate(Progress…) manually.
§ The
task can be executed only once (an exception will be thrown if a second
execution is attempted.)
The Service class will
look like this:
MyService.java
public class MyService extends
Service
{
@Override
public void
onCreate()
{
super.onCreate();
}
public class
MyTask extends AsyncTask<Void,
Integer, String>
{
protected void
onPreExecute()
{
super.onPreExecute();
}
protected String doInBackground(Void...
params)
{
return null;
}
protected void
onProgressUpdate(Integer... values)
{
super.onProgressUpdate(values);
}
protected void
onPostExecute(String result)
{
super.onPostExecute(result);
}
}
@Override
public int
onStartCommand(Intent intent, int
flags, int startId)
{
return super.onStartCommand(intent,
flags, startId);
}
@Override
public void
onDestroy()
{
super.onDestroy();
}
@Override
public IBinder onBind(Intent intent) {
// TODO Auto-generated method stub
return null;
}
}
