Android提高第五篇之Service
http://blog.csdn.net/hellogv/archive/2010/11/08/5994952.aspx
上次介绍了Activity以及Intent的使用，这次就介绍Service，如果把Activity比喻为前台程序，那么Service就是后台程序，Service的整个生命周期都只会在后台执行。Service跟Activity一样也由Intent调用。在工程里想要添加一个Service，先新建继承Service的类，然后到AndroidManifest.xml -> Application ->Application Nodes中的Service标签中添加。
Service要由Activity通过startService 或者 bindService来启动，Intent负责传递参数。先贴出本文程序运行截图：
本文主要讲解Service的调用，以及其生命周期。
上图是startService之后再stopService的Service状态变化。
上图是bindService之后再unbindService的Service状态变化。
startService与bindService都可以启动Service，那么它们之间有什么区别呢？它们两者的区别就是使Service的周期改变。由startService启动的Service必须要有stopService来结束Service，不调用stopService则会造成Activity结束了而Service还运行着。bindService启动的Service可以由unbindService来结束，也可以在Activity结束之后(onDestroy)自动结束。
上图是startService之后再Activity.finish()的Service状态变化，Service还在跑着。
上图是bindService之后再Activity.finish()的Service状态变化，Service最后自动unbindService。
main.xml代码：
<?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:orientation="vertical" android:layout_width="fill_parent" android:layout_height="fill_parent"> <Button android:layout_width="wrap_content" android:layout_height="wrap_content" android:id="@+id/btnStartMyService" android:text="StartMyService"></Button> <Button android:layout_width="wrap_content" android:layout_height="wrap_content" android:id="@+id/btnStopMyService" android:text="StopMyService"></Button> <Button android:layout_width="wrap_content" android:layout_height="wrap_content" android:id="@+id/btnBindMyService" android:text="BindMyService"></Button> <Button android:layout_width="wrap_content" android:layout_height="wrap_content" android:id="@+id/btnUnbindMyService" android:text="UnbindMyService"></Button> <Button android:layout_width="wrap_content" android:layout_height="wrap_content" android:id="@+id/btnExit" android:text="退出程序"></Button> </LinearLayout>
package com.testService; import android.app.Activity; import android.app.Service; import android.content.ComponentName; import android.content.Intent; import android.content.ServiceConnection; import android.os.Bundle; import android.os.IBinder; import android.util.Log; import android.view.View; import android.widget.Button; public class testService extends Activity { Button btnStartMyService,btnStopMyService,btnBindMyService,btnUnbindMyService,btnExit; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); btnStartMyService=(Button)this.findViewById(R.id.btnStartMyService); btnStartMyService.setOnClickListener(new ClickEvent()); btnStopMyService=(Button)this.findViewById(R.id.btnStopMyService); btnStopMyService.setOnClickListener(new ClickEvent()); btnBindMyService=(Button)this.findViewById(R.id.btnBindMyService); btnBindMyService.setOnClickListener(new ClickEvent()); btnUnbindMyService=(Button)this.findViewById(R.id.btnUnbindMyService); btnUnbindMyService.setOnClickListener(new ClickEvent()); btnExit=(Button)this.findViewById(R.id.btnExit); btnExit.setOnClickListener(new ClickEvent()); } @Override public void onDestroy() { super.onDestroy(); Log.e("Activity","onDestroy"); } private ServiceConnection _connection = new ServiceConnection() { @Override public void onServiceConnected(ComponentName arg0, IBinder arg1) { // TODO Auto-generated method stub } @Override public void onServiceDisconnected(ComponentName name) { // TODO Auto-generated method stub } }; class ClickEvent implements View.OnClickListener{ @Override public void onClick(View v) { Intent intent=new Intent(testService.this,MyService.class); if(v==btnStartMyService){ testService.this.startService(intent); } else if(v==btnStopMyService){ testService.this.stopService(intent); } else if(v==btnBindMyService){ testService.this.bindService(intent, _connection, Service.BIND_AUTO_CREATE); } else if(v==btnUnbindMyService){ if(MyService.ServiceState=="onBind")//Service绑定了之后才能解绑 testService.this.unbindService(_connection); } else if(v==btnExit) { testService.this.finish(); } } } } package com.testService; import android.app.Service; import android.content.Intent; import android.os.IBinder; import android.util.Log; public class MyService extends Service { static public String ServiceState=""; @Override public IBinder onBind(Intent arg0) { Log.e("Service", "onBind"); ServiceState="onBind"; return null; } @Override public boolean onUnbind(Intent intent){ super.onUnbind(intent); Log.e("Service", "onUnbind"); ServiceState="onUnbind"; return false; } @Override public void onCreate(){ super.onCreate(); Log.e("Service", "onCreate"); ServiceState="onCreate"; } @Override public void onDestroy(){ super.onDestroy(); Log.e("Service", "onDestroy"); ServiceState="onDestroy"; } @Override public void onStart(Intent intent,int startid){ super.onStart(intent, startid); Log.e("Service", "onStart"); ServiceState="onStart"; } }