Android Local Bound Service Example with Binder and ServiceConnection
July 17, 2015
<service android:name=".MyLocalService"/>
Bound Service
A bound service is a service which allows other applications to bind and interact with it. This is the implementation of Service where we have to override onBind() that will return IBinder.
public IBinder onBind(Intent intent) {
return binder;
}
bindService(Intent service, ServiceConnection conn, int flags): Binds the service. We need to pass intent which is instantiated using our service class. Pass the
ServiceConnection instance created for service. flag is context value which can be as follows BIND_ABOVE_CLIENT, BIND_ADJUST_WITH_ACTIVITY, BIND_ALLOW_OOM_MANAGEMENT, BIND_AUTO_CREATE, BIND_DEBUG_UNBIND, BIND_IMPORTANT, BIND_NOT_FOREGROUND, BIND_WAIVE_PRIORITY
unbindService(ServiceConnection conn): Unbinds the bound service from other application for the given connection.
We call the above methods from the main thread of our activity.
Binder
android.os.Binder implements android.os.IBinder. If our client and service are in same application, we can implement our own Binder. To use it we can create public inner class which will extend Binder within our service and finally return the instance of this inner class by onBind() method. Extending Binder works if our service is private to our application that is known as local binding.
ServiceConnection
android.content.ServiceConnection is an interface which is used to monitor the state of service. We need to override following methods.onServiceConnected(ComponentName name, IBinder service) : This is called when service is connected to the application.
onServiceDisconnected(ComponentName name) : This is called when service is disconnected.
Complete Example
MainActivity.java
package com.concretepage;
import java.util.Date;
import android.app.Activity;
import android.content.ComponentName;
import android.content.Context;
import android.content.Intent;
import android.content.ServiceConnection;
import android.os.Bundle;
import android.os.IBinder;
import android.view.View;
import android.widget.Toast;
import com.concretepage.MyLocalService.LocalBinder;
public class MainActivity extends Activity {
MyLocalService localService;
private boolean isBound = false;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
}
@Override
protected void onStart() {
super.onStart();
Intent intent = new Intent(this, MyLocalService.class);
bindService(intent, connection, Context.BIND_AUTO_CREATE);
}
@Override
protected void onStop() {
super.onStop();
if (isBound) {
unbindService(connection);
isBound = false;
}
}
public void dispalyDate(View v) {
if (isBound) {
Date date = localService.getCurrentDate();
Toast.makeText(this, String.valueOf(date), Toast.LENGTH_SHORT).show();
}
}
private ServiceConnection connection = new ServiceConnection() {
@Override
public void onServiceConnected(ComponentName className, IBinder service) {
LocalBinder binder = (LocalBinder) service;
localService = binder.getService();
isBound = true;
}
@Override
public void onServiceDisconnected(ComponentName arg0) {
isBound = false;
}
};
}
MyLocalService.java
package com.concretepage;
import java.util.Calendar;
import java.util.Date;
import android.app.Service;
import android.content.Intent;
import android.os.Binder;
import android.os.IBinder;
public class MyLocalService extends Service {
private final IBinder binder = new LocalBinder();
public class LocalBinder extends Binder {
MyLocalService getService() {
return MyLocalService.this;
}
}
@Override
public IBinder onBind(Intent intent) {
return binder;
}
public Date getCurrentDate() {
return Calendar.getInstance().getTime();
}
}
main.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#C98C00"
tools:context=".MainActivity">
<Button
android:id="@+id/btn_date"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="@string/btn_msg"
android:onClick="dispalyDate" />
</LinearLayout>
AndroidManifest.xml
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.concretepage"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk android:minSdkVersion="11"/>
<application
android:allowBackup ="false"
android:icon="@drawable/ic_launcher"
android:label="@string/app_name" >
<activity android:name=".MainActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<service android:name=".MyLocalService"/>
</application>
</manifest>
strings.xml
<?xml version="1.0" encoding="utf-8"?>
<resources>
<string name="app_name">Concrete Page</string>
<string name="btn_msg">Show Current Date</string>
</resources>
Output
