理解Service和BroadcastReceiver
2010-05-15 12:37
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Service与Activity类似,也需要在Manifest.xml对应的<service>标签声明.其回调方法有:onCreate(),onStart(),onDestroy(); Service不能自己启动,必须用Context对象(例如一个Activity)调用StartService()或bindService()启动,两者启动的生命周期是不同的.
调用StartService()时,若Service未启动,则先onCreate(),再onStart();若启动则直接onStart();Context对象可以通过stopService()关闭服务,Service自身也可以用stopSelf()或stopSelfResult来关闭,关闭前会调用onDestroy().
bindService()会使当前的Context对象通过一个ServiceConnection对象绑定到指定的服务.
若服务未启动,则首先onCreate(),再onBind()
若绑定服务的Context对象被销毁,则服务会调用onUnbind()和onDestroy().
BroadcastReceiver不能绑定服务.
Context对象可以unbindservice(),此时服务会调用unbind(),若服务是通过bindService()启动的,还会调用onDestroy().
BroadcastReceiver
首先将需要发送的信息包装成Intent对象,用Context.sendBroadcast(),sendOrderedBroadcast(),sendStickyBroadcast()以广播形式发送出去.则所有注册的BroadcasrReceiver的过滤器会做匹配检测,若匹配通过,则调用BroadcasrReceiver的onReceive()方法.
sendBroadcast(),sendStickyBroadcast()的消息被接收后,所有匹配的BroadcasrReceiver会随机执行onReceive().
sendOrderedBroadcast()则根据BroadcasrReceiver注册时设置的过滤器优先级顺序进行.
sendStickyBroadcast(),Intent发出后会一直存在,并且在以后调用registerReceiver()注册匹配相同的Intent时会直接返回该Intent.
注册BroadcastReceiver的两种方式:
1.在Menifest.xml文件中用<receiver>标签注明,内部用<intent-filter>设置过滤器.
2.在代码中定义并设置好一个IntentFilter对象,在需要的地方用Context.registerReceiver()注册,取消注册用ujnregisterReceiver(),r 若Context对象销毁,则BroadcastReceiver也自动取消注册
注册BroadcastReceiver和sendBroadcast()时可以指定接收权限,此时只有在Manifest.xml中用<uses-permission>授权才可以接收到
调用StartService()时,若Service未启动,则先onCreate(),再onStart();若启动则直接onStart();Context对象可以通过stopService()关闭服务,Service自身也可以用stopSelf()或stopSelfResult来关闭,关闭前会调用onDestroy().
bindService()会使当前的Context对象通过一个ServiceConnection对象绑定到指定的服务.
若服务未启动,则首先onCreate(),再onBind()
若绑定服务的Context对象被销毁,则服务会调用onUnbind()和onDestroy().
BroadcastReceiver不能绑定服务.
Context对象可以unbindservice(),此时服务会调用unbind(),若服务是通过bindService()启动的,还会调用onDestroy().
BroadcastReceiver
首先将需要发送的信息包装成Intent对象,用Context.sendBroadcast(),sendOrderedBroadcast(),sendStickyBroadcast()以广播形式发送出去.则所有注册的BroadcasrReceiver的过滤器会做匹配检测,若匹配通过,则调用BroadcasrReceiver的onReceive()方法.
sendBroadcast(),sendStickyBroadcast()的消息被接收后,所有匹配的BroadcasrReceiver会随机执行onReceive().
sendOrderedBroadcast()则根据BroadcasrReceiver注册时设置的过滤器优先级顺序进行.
sendStickyBroadcast(),Intent发出后会一直存在,并且在以后调用registerReceiver()注册匹配相同的Intent时会直接返回该Intent.
注册BroadcastReceiver的两种方式:
1.在Menifest.xml文件中用<receiver>标签注明,内部用<intent-filter>设置过滤器.
2.在代码中定义并设置好一个IntentFilter对象,在需要的地方用Context.registerReceiver()注册,取消注册用ujnregisterReceiver(),r 若Context对象销毁,则BroadcastReceiver也自动取消注册
注册BroadcastReceiver和sendBroadcast()时可以指定接收权限,此时只有在Manifest.xml中用<uses-permission>授权才可以接收到
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