一。生命周期:
startService()方式启动,Service是通过接受Intent并且会经历onCreate()和onStart()。当用户在发出意图使之销毁时会经历onDestroy();( onCreate-->onStart-->onDestory )
bindService()方式启动,与Activity绑定的时候,会经历onCreate()和onBind(),而当Activity被销毁的时候,Service会先调用onUnbind()然后是onDestroy()。( onCreate-->onBind -->onUnbind-->onDestory)
二。控制方式:
StartService的控制方式需要使用固定的方法,对Service进行单一的操作。
而BindService由于与Activity绑定,不用考虑其生命周期问题,并且从发送Intent的被动操作,变为可以主动对Service对象进行操作,我们甚至可以建立一个Handler类,对Service进行相关的操作。大大加强了Service的灵活性、可操作性。
总结:对于简单的应用startService()启动方式能带来更少的代码,简单的操作。对于复杂的应用bindService()方式,虽然带来的更多的编码,但同时也带来了更好的可操作性,使其使用起来更像Activity。
注意:
Service的生命周期方法比Activity少一些,只有onCreate, onStart, onDestroy 我们有两种方式启动一个Service,他们对Service生命周期的影响是不一样的。
1 通过startService
Service会经历 onCreate --> onStart
stopService的时候直接onDestroy,如果是 调用者 直接退出而没有调用stopService的话,Service会一直在后台运行,下次调用者再起来仍然可以stopService。
2 通过bindService
Service只会运行onCreate, 这个时候 调用者和Service绑定在一起,调用者退出了,Srevice就会调用onUnbind-->onDestroyed,所谓绑定在一起就共存亡了。
注意:Service的onCreate的方法只会被调用一次,
就是你无论多少次的startService又 bindService,Service只被创建一次。
如果先是bind了,那么start的时候就直接运行Service的onStart方法,
如果先是start,那么bind的时候就直接运行onBind方法。如果你先bind上了,就stop不掉了,
只能先UnbindService, 再StopService,所以是先start还是先bind行为是有区别的。
代码:
一。startService -->service内容:
public class MyService extends Service{ private static final String TAG = "MyService"; MediaPlayer player; @Override public IBinder onBind(Intent intent) { return null; } @Override //服务启动前进行的配置 public void onCreate() { Toast.makeText(this, "My Service created", Toast.LENGTH_LONG).show(); Log.i(TAG, "onCreate"); //播放设置 player = MediaPlayer.create(this, R.raw.music);//提供音乐的位置 player.setLooping(false); //是否循环播放音乐 } @Override //关闭服务 public void onDestroy() { Toast.makeText(this, "My Service Stoped", Toast.LENGTH_LONG).show(); Log.i(TAG, "onDestroy"); player.stop(); } @Override //启动服务 public void onStart(Intent intent, int startid) { Toast.makeText(this, "My Service Start", Toast.LENGTH_LONG).show(); Log.i(TAG, "onStart"); player.start(); } } Activity的内容:
public class Activityone extends Activity{ private static final String TAG = "ServiceDemo"; private Button mybuttonone1; private Button mybuttonone2; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_one); mybuttonone1 = (Button)findViewById(R.id.buttonone1); mybuttonone2 = (Button)findViewById(R.id.buttonone2); //service通过startservice启动服务 //首先调用mybuttonone1的onclick方法,然后调用myservice的onclick()方法,再然后调用onstart()方法 mybuttonone1.setOnClickListener(new OnClickListener() { @Override public void onClick(View v) { Log.i(TAG, "onClick: starting service"); startService(new Intent(Activityone.this, MyService.class)); } }); //service通过startservice关闭服务 //首先调用mybuttonone2的onclick方法,然后调用myservice的onstop()方法 mybuttonone2.setOnClickListener(new OnClickListener() { @Override public void onClick(View v) { Log.i(TAG, "onClick: stopping service"); stopService(new Intent(Activityone.this, MyService.class)); } }); mybuttonone1.setOnClickListener(new myclicklistener()); mybuttonone2.setOnClickListener(new myclicklistener()); } class myclicklistener implements OnClickListener{ public void onClick(View src) { switch (src.getId()) { case R.id.buttonone1: Log.i(TAG, "onClick: starting service"); startService(new Intent(Activityone.this, MyService.class)); //startservice 执行的步骤: onclick()-->onstart() break; case R.id.buttonone2: Log.i(TAG, "onClick: stopping service"); stopService(new Intent(Activityone.this, MyService.class)); //startservice 执行的步骤: onDestroy() break; } } } } 二。BindService -->service内容:
public class BindService extends Service { private MyBinder myBinder = new MyBinder(); private static final String TAG = "BindService"; private MediaPlayer play; @Override public IBinder onBind(Intent intent) { Log.i(TAG, "BindService-->onBind()"); play=MediaPlayer.create(this, R.raw.music); play.setLooping(false); return myBinder; } public class MyBinder extends Binder{ public BindService getService(){ Log.i(TAG, "BindService-->getService()"); return BindService.this; } } public void MyMethod(){ Log.i(TAG, "BindService-->MyMethod()"); play.start(); } } Activity的代码:
public class Activitytwo extends Activity{ private Button mybutton1; private Button mybutton2; private boolean flag; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_two); mybutton1=(Button)findViewById(R.id.buttontwo1); mybutton2=(Button)findViewById(R.id.buttontwo2); mybutton1.setOnClickListener(new myclicklistener()); mybutton2.setOnClickListener(new myclicklistener()); } class myclicklistener implements OnClickListener{ @Override public void onClick(View v) { // TODO Auto-generated method stub switch (v.getId()) { case R.id.buttontwo1: System.out.println("打开bind1"); bindService(); break; case R.id.buttontwo2: System.out.println("关闭bind1"); unBind(); break; default: break; } } } private void bindService(){ System.out.println("打开bind2"); Intent intent = new Intent(Activitytwo.this,BindService.class); bindService(intent, conn, Context.BIND_AUTO_CREATE); } private void unBind(){ System.out.println("关闭bind2"); if(flag == true){ unbindService(conn); flag = false; } } private ServiceConnection conn = new ServiceConnection() { @Override public void onServiceDisconnected(ComponentName name) { System.out.println("关闭bind3"); } @Override public void onServiceConnected(ComponentName name, IBinder service) { System.out.println("打开bind3"); MyBinder binder = (MyBinder)service; BindService bindService = binder.getService(); bindService.MyMethod(); flag = true; } }; }