service的原理在这里就不在复述了，下面直接介绍service的两种启动方式及生命周期。
首先建立一个serviceDemo，如图所示。
然后修改main.xml布局文件：
<?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" >
<TextView
android:id="@+id/text"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="@string/hello" />
<Button
android:id="@+id/startservice"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="startService" />
<Button
android:id="@+id/stopservice"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="stopService" />
<Button
android:id="@+id/bindservice"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="bindService" />
<Button
android:id="@+id/unbindservice"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="unbindService" />
</LinearLayout>
接下来 建立一个MyService来继承service
public class MyService extends Service {
private static final String TAG = "MyService";
private MyBinder mBinder=new MyBinder();
@Override
public IBinder onBind(Intent arg0) {
// TODO Auto-generated method stub
Log.e(TAG, "start IBinder~~~");
return mBinder;
}
@Override
public void onCreate() {
// TODO Auto-generated method stub
Log.e(TAG, "start onCreate~~~");
super.onCreate();
}
@Override
public void onDestroy() {
// TODO Auto-generated method stub
Log.e(TAG, "start onDestroy~~~");
super.onDestroy();
}
@Override
public int onStartCommand(Intent intent, int flags, int startId) {
// TODO Auto-generated method stub
Log.e(TAG, "start onStartCommand~~~");
return super.onStartCommand(intent, flags, startId);
}
@Override
public boolean onUnbind(Intent intent) {
// TODO Auto-generated method stub
Log.e(TAG, "start onUnbind~~~");
return super.onUnbind(intent);
}
public String getSystemTime(){
/*Time t=new Time();
t.setToNow();*/
SimpleDateFormat format=new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
return format.format(new Date());
}
public class MyBinder extends Binder{
public MyService getService(){
return MyService.this;
}
}
}
分别实现了他的相应的生命周期方法，然后修改主activity为：
public class ServiceDemoActivity extends Activity implements OnClickListener{
/** Called when the activity is first created. */
private MyService mMyService;
private TextView mTextView;
private Context mContext;
private Button startServiceButton;
private Button stopServiceButton;
private Button bindServiceButton;
private Button unbindServiceButton;
//这里需要用到ServiceConnection在Context.bindService和context.unBindService()里用到
private ServiceConnection mServiceConnection = new ServiceConnection() {
//当我bindService时，让TextView显示MyService里getSystemTime()方法的返回值
@Override
public void onServiceConnected(ComponentName name, IBinder service) {
// TODO Auto-generated method stub
mMyService = ((MyService.MyBinder)service).getService();
mTextView.setText("I am frome Service :" + mMyService.getSystemTime());
}
@Override
public void onServiceDisconnected(ComponentName name) {
// TODO Auto-generated method stub
}
};
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
setupViews();
}
private void setupViews(){
mContext=this;
mTextView=(TextView) this.findViewById(R.id.text);
startServiceButton = (Button)findViewById(R.id.startservice);
stopServiceButton = (Button)findViewById(R.id.stopservice);
bindServiceButton = (Button)findViewById(R.id.bindservice);
unbindServiceButton = (Button)findViewById(R.id.unbindservice);
startServiceButton.setOnClickListener(this);
stopServiceButton.setOnClickListener(this);
bindServiceButton.setOnClickListener(this);
unbindServiceButton.setOnClickListener(this);
}
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
if(v == startServiceButton){
Intent i = new Intent();
i.setClass(ServiceDemoActivity.this, MyService.class);
mContext.startService(i);
}else if(v == stopServiceButton){
Intent i = new Intent();
i.setClass(ServiceDemoActivity.this, MyService.class);
mContext.stopService(i);
}else if(v == bindServiceButton){
Intent i = new Intent();
i.setClass(ServiceDemoActivity.this, MyService.class);
mContext.bindService(i, mServiceConnection, BIND_AUTO_CREATE);
}else{
mContext.unbindService(mServiceConnection);
}
}
}
在这里不要忘记在AndroidManifest.xml里注册service
下面看一下运行效果：
点击startService按钮看一下打印的log日志：
首先开启一个start服务先是执行了onCreate方法和onStartCommand方法,然后点击stopService按钮：
执行了onDestroy方法，知道了这些生命周期方法后我们就可以在这些生命周期方法里做一些相应的事件了。
下面点击一下bindService按钮看会出现什么效果吧：
在最上方打印出了系统时间，绑定服务其实就是让服务执行完后，返回一些数据给启动它的组件比如activity。
这是后台打印的log：
最后点击unbindService取消绑定：
绑定服务 生命周期结束 。
下面让我们再看一下官方给出的两种服务的生命周期图：
这样是不是一眼就看明白了。