Android提高第五篇之Service

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：

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1. <? xml   version = "1.0"   encoding = "utf-8" ?>   
2. < LinearLayout   xmlns:android = "http://schemas.android.com/apk/res/android"   
3.     android:orientation = "vertical"   android:layout_width = "fill_parent"   
4.     android:layout_height = "fill_parent" >   
5.     < Button   android:layout_width = "wrap_content"   
6.         android:layout_height = "wrap_content"   android:id = "@+id/btnStartMyService"   
7.         android:text = "StartMyService" > </ Button >   
8.     < Button   android:layout_width = "wrap_content"   
9.         android:layout_height = "wrap_content"   android:id = "@+id/btnStopMyService"   
10.         android:text = "StopMyService" > </ Button >   
11.     < Button   android:layout_width = "wrap_content"   
12.         android:layout_height = "wrap_content"   android:id = "@+id/btnBindMyService"   
13.         android:text = "BindMyService" > </ Button >   
14.     < Button   android:layout_width = "wrap_content"   
15.         android:layout_height = "wrap_content"   android:id = "@+id/btnUnbindMyService"   
16.         android:text = "UnbindMyService" > </ Button >   
17.     < Button   android:layout_width = "wrap_content"   
18.         android:layout_height = "wrap_content"   android:id = "@+id/btnExit"   
19.         android:text = "退出程序" > </ Button >   
20. </ LinearLayout >   

<?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>

testService.java的源码：

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1. package  com.testService;  
2.   
3. import  android.app.Activity;  
4. import  android.app.Service;  
5. import  android.content.ComponentName;  
6. import  android.content.Intent;  
7. import  android.content.ServiceConnection;  
8. import  android.os.Bundle;  
9. import  android.os.IBinder;  
10. import  android.util.Log;  
11. import  android.view.View;  
12. import  android.widget.Button;  
13.   
14. public   class  testService  extends  Activity {  
15.     Button btnStartMyService,btnStopMyService,btnBindMyService,btnUnbindMyService,btnExit;  
16.     @Override   
17.     public   void  onCreate(Bundle savedInstanceState) {  
18.         super .onCreate(savedInstanceState);  
19.         setContentView(R.layout.main);  
20.         btnStartMyService=(Button)this .findViewById(R.id.btnStartMyService);  
21.         btnStartMyService.setOnClickListener(new  ClickEvent());  
22.           
23.         btnStopMyService=(Button)this .findViewById(R.id.btnStopMyService);  
24.         btnStopMyService.setOnClickListener(new  ClickEvent());  
25.           
26.         btnBindMyService=(Button)this .findViewById(R.id.btnBindMyService);  
27.         btnBindMyService.setOnClickListener(new  ClickEvent());  
28.           
29.         btnUnbindMyService=(Button)this .findViewById(R.id.btnUnbindMyService);  
30.         btnUnbindMyService.setOnClickListener(new  ClickEvent());   
31.           
32.         btnExit=(Button)this .findViewById(R.id.btnExit);  
33.         btnExit.setOnClickListener(new  ClickEvent());  
34.     }  
35.     @Override   
36.     public   void  onDestroy()  
37.     {  
38.         super .onDestroy();  
39.         Log.e("Activity" , "onDestroy" );  
40.     }  
41.       
42.     private  ServiceConnection _connection =  new  ServiceConnection() {    
43.         @Override   
44.         public   void  onServiceConnected(ComponentName arg0, IBinder arg1) {  
45.             // TODO Auto-generated method stub   
46.         }  
47.   
48.         @Override   
49.         public   void  onServiceDisconnected(ComponentName name) {  
50.             // TODO Auto-generated method stub   
51.         }    
52.     };    
53.     class  ClickEvent  implements  View.OnClickListener{  
54.   
55.         @Override   
56.         public   void  onClick(View v) {  
57.             Intent intent=new  Intent(testService. this ,MyService. class );  
58.             if (v==btnStartMyService){  
59.                 testService.this .startService(intent);  
60.             }  
61.             else   if (v==btnStopMyService){  
62.                 testService.this .stopService(intent);  
63.             }  
64.             else   if (v==btnBindMyService){  
65.                 testService.this .bindService(intent, _connection, Service.BIND_AUTO_CREATE);  
66.             }  
67.             else   if (v==btnUnbindMyService){  
68.                 if (MyService.ServiceState== "onBind" ) //Service绑定了之后才能解绑   
69.                     testService.this .unbindService(_connection);  
70.             }  
71.             else   if (v==btnExit)  
72.             {  
73.                 testService.this .finish();  
74.             }  
75.               
76.         }  
77.           
78.     }  
79. }  

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(); } } } }

MyService.java的源码：

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1. package  com.testService;  
2.   
3. import  android.app.Service;  
4. import  android.content.Intent;  
5. import  android.os.IBinder;  
6. import  android.util.Log;  
7.   
8. public   class  MyService  extends  Service {  
9.     static   public  String ServiceState= "" ;  
10.     @Override   
11.     public  IBinder onBind(Intent arg0) {  
12.         Log.e("Service" ,  "onBind" );  
13.         ServiceState="onBind" ;  
14.         return   null ;  
15.     }  
16.     @Override   
17.     public   boolean  onUnbind(Intent intent){  
18.         super .onUnbind(intent);  
19.         Log.e("Service" ,  "onUnbind" );  
20.         ServiceState="onUnbind" ;  
21.         return   false ;  
22.           
23.     }  
24.     @Override   
25.     public   void  onCreate(){  
26.         super .onCreate();  
27.         Log.e("Service" ,  "onCreate" );  
28.         ServiceState="onCreate" ;  
29.     }  
30.     @Override   
31.     public   void  onDestroy(){  
32.         super .onDestroy();  
33.         Log.e("Service" ,  "onDestroy" );  
34.         ServiceState="onDestroy" ;  
35.     }  
36.     @Override   
37.     public   void  onStart(Intent intent, int  startid){  
38.         super .onStart(intent, startid);  
39.         Log.e("Service" ,  "onStart" );  
40.         ServiceState="onStart" ;  
41.     }  
42.   
43. }