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：

 <? 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 >

<?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：

 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.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：

 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" ;
     }

 }