玩转Android---组件篇---Service(服务)

Service是Andorid系统提供的四大组件之一，它的地位和Activity是并列的，只是使用的频率没有Activity高。Service就是运行于后台的一种服务程序，一般很少和用户交互，因此没有可视化界面。

定义一个Service类只要继承Service类即可，实现其生命周期中的方法就可以了，另外，一个定义好的Service组件必须要在AndoridManifest.xml文件中注册才能够使用。

Service有自己的生命周期，可以调用startService()启动一个Service或者使用bindService()来绑定一个service，还可以通过RPC(远程进程调用)机制来实现不同进程间Service的调用。

Service中定义了一系列和自身生命周期相关的方法：

onBind(Intent intent):是必须实现的一个方法，返回一个绑定的接口给Service。

onCreate()：当Service第一次被创建时，由系统调用。

onStart(Intent intent,int startId)：当通过startService()方法启动Service时，该方法被调用。

onDestroy()：当Service不再使用，系统调用该方法。

实例如下：

MyService.java

Java代码

1. /*
2. *@authorhualang
3. */
4. packageorg.hualang.service;
6. importandroid.app.Service;
7. importandroid.content.Intent;
8. importandroid.os.IBinder;
9. importandroid.util.Log;
10. importandroid.widget.Toast;
12. publicclassMyServiceextendsService{
14. @Override
15. publicIBinderonBind(Intentintent){
16. //TODOAuto-generatedmethodstub
17. Log.i("SERVICE","onBind.................");
18. Toast.makeText(MyService.this,"onBind.................",Toast.LENGTH_LONG).show();
19. returnnull;
20. }
22. publicvoidonCreate()
23. {
24. Log.i("SERVICE","onCreate................");
25. Toast.makeText(MyService.this,"onCreate................",Toast.LENGTH_LONG).show();
26. }
27. publicvoidonStart(Intentintent,intstartId)
28. {
29. Log.i("SERVICE","onStart.................");
30. Toast.makeText(MyService.this,"onStart.................",Toast.LENGTH_LONG).show();
31. }
32. publicvoidonDestroy()
33. {
34. Log.i("SERVICE","onDestroy.................");
35. Toast.makeText(MyService.this,"onDestroy.................",Toast.LENGTH_LONG).show();
36. }
37. }

/* * @author hualang */package org.hualang.service;import android.app.Service;import android.content.Intent;import android.os.IBinder;import android.util.Log;import android.widget.Toast;public class MyService extends Service {	@Override	public IBinder onBind(Intent intent) {		// TODO Auto-generated method stub		Log.i("SERVICE", "onBind.................");		Toast.makeText(MyService.this, "onBind.................", Toast.LENGTH_LONG).show();		return null;	}		public void onCreate()	{		Log.i("SERVICE", "onCreate................");		Toast.makeText(MyService.this, "onCreate................", Toast.LENGTH_LONG).show();	}	public void onStart(Intent intent,int startId)	{		Log.i("SERVICE", "onStart.................");		Toast.makeText(MyService.this, "onStart.................", Toast.LENGTH_LONG).show();	}	public void onDestroy()	{		Log.i("SERVICE", "onDestroy.................");		Toast.makeText(MyService.this, "onDestroy.................", Toast.LENGTH_LONG).show();	}}

ServiceTest.java

Java代码

1. /*
2. *@authorhualang
3. */
4. packageorg.hualang.service;
6. importandroid.app.Activity;
7. importandroid.app.Service;
8. importandroid.content.ComponentName;
9. importandroid.content.Intent;
10. importandroid.content.ServiceConnection;
11. importandroid.os.Bundle;
12. importandroid.os.IBinder;
13. importandroid.util.Log;
14. importandroid.view.View;
15. importandroid.view.View.OnClickListener;
16. importandroid.widget.Button;
17. importandroid.widget.Toast;
19. publicclassServiceTestextendsActivity{
20. /**Calledwhentheactivityisfirstcreated.*/
21. privateButtonstartService,stopService,bindService,unbindService;
22. @Override
23. publicvoidonCreate(BundlesavedInstanceState){
24. super.onCreate(savedInstanceState);
25. setContentView(R.layout.main);
26. startService=(Button)findViewById(R.id.startButton);
27. stopService=(Button)findViewById(R.id.stopButton);
28. bindService=(Button)findViewById(R.id.bindButton);
29. unbindService=(Button)findViewById(R.id.unbindButton);
30. startService.setOnClickListener(startListener);
31. stopService.setOnClickListener(stopListener);
32. bindService.setOnClickListener(bindListener);
33. unbindService.setOnClickListener(unbindListener);
35. }
36. privateOnClickListenerstartListener=newOnClickListener()
37. {
39. @Override
40. publicvoidonClick(Viewv){
41. //TODOAuto-generatedmethodstub
42. Intentintent=newIntent();
43. intent.setAction("org.hualang.service.action.MYSERVICE");
44. startService(intent);
45. }
47. };
48. privateOnClickListenerstopListener=newOnClickListener()
49. {
51. @Override
52. publicvoidonClick(Viewv){
53. //TODOAuto-generatedmethodstub
54. Intentintent=newIntent();
55. intent.setAction("org.hualang.service.action.MYSERVICE");
56. stopService(intent);
57. }
59. };
60. privateServiceConnectionconn=newServiceConnection()
61. {
63. @Override
64. publicvoidonServiceConnected(ComponentNamename,IBinderservice){
65. //TODOAuto-generatedmethodstub
66. Log.i("SERVICE","connectionsuccess");
67. Toast.makeText(ServiceTest.this,"connectionsuccess",Toast.LENGTH_LONG).show();
68. }
70. @Override
71. publicvoidonServiceDisconnected(ComponentNamename){
72. //TODOAuto-generatedmethodstub
73. Log.i("SERVICE","connectionsuccess");
74. Toast.makeText(ServiceTest.this,"connectionfailure",Toast.LENGTH_LONG).show();
75. }
77. };
78. privateOnClickListenerbindListener=newOnClickListener()
79. {
81. @Override
82. publicvoidonClick(Viewv){
83. //TODOAuto-generatedmethodstub
84. Intentintent=newIntent();
85. intent.setAction("org.hualang.service.action.MYSERVICE");
86. bindService(intent,conn,Service.BIND_AUTO_CREATE);
87. }
89. };
90. privateOnClickListenerunbindListener=newOnClickListener()
91. {
93. @Override
94. publicvoidonClick(Viewv){
95. //TODOAuto-generatedmethodstub
96. Intentintent=newIntent();
97. intent.setAction("org.hualang.service.action.MYSERVICE");
98. unbindService(conn);
99. }
101. };
102. }

/* * @author hualang */package org.hualang.service;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.view.View.OnClickListener;import android.widget.Button;import android.widget.Toast;public class ServiceTest extends Activity {    /** Called when the activity is first created. */	private Button startService,stopService,bindService,unbindService;    @Override    public void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.main);        startService=(Button)findViewById(R.id.startButton);        stopService=(Button)findViewById(R.id.stopButton);        bindService=(Button)findViewById(R.id.bindButton);        unbindService=(Button)findViewById(R.id.unbindButton);        startService.setOnClickListener(startListener);        stopService.setOnClickListener(stopListener);        bindService.setOnClickListener(bindListener);        unbindService.setOnClickListener(unbindListener);            }    private OnClickListener startListener=new OnClickListener()    {		@Override		public void onClick(View v) {			// TODO Auto-generated method stub			Intent intent=new Intent();			intent.setAction("org.hualang.service.action.MYSERVICE");			startService(intent);		}    	    };    private OnClickListener stopListener=new OnClickListener()    {		@Override		public void onClick(View v) {			// TODO Auto-generated method stub			Intent intent=new Intent();			intent.setAction("org.hualang.service.action.MYSERVICE");			stopService(intent);		}    	    };    private ServiceConnection conn=new ServiceConnection()    {		@Override		public void onServiceConnected(ComponentName name, IBinder service) {			// TODO Auto-generated method stub			Log.i("SERVICE", "connection success");			Toast.makeText(ServiceTest.this, "connection success", Toast.LENGTH_LONG).show();		}		@Override		public void onServiceDisconnected(ComponentName name) {			// TODO Auto-generated method stub			Log.i("SERVICE", "connection success");			Toast.makeText(ServiceTest.this, "connection failure", Toast.LENGTH_LONG).show();		}    	    };    private OnClickListener bindListener=new OnClickListener()    {		@Override		public void onClick(View v) {			// TODO Auto-generated method stub			Intent intent=new Intent();			intent.setAction("org.hualang.service.action.MYSERVICE");			bindService(intent,conn,Service.BIND_AUTO_CREATE);		}    	    };    private OnClickListener unbindListener=new OnClickListener()    {		@Override		public void onClick(View v) {			// TODO Auto-generated method stub			Intent intent=new Intent();			intent.setAction("org.hualang.service.action.MYSERVICE");			unbindService(conn);		}    	    };}

在AndroidManifest.xml文件中注册Service如下

Java代码

1. <serviceandroid:name="MyService">
2. <intent-filter>
3. <actionandroid:name="org.hualang.service.action.MYSERVICE"/>
4. </intent-filter>
5. </service>

<service android:name="MyService">			<intent-filter>				<action android:name="org.hualang.service.action.MYSERVICE"/>			</intent-filter>		</service>

main.xml布局文件

Java代码

1. <?xmlversion="1.0"encoding="utf-8"?>
2. <LinearLayoutxmlns:android="http://schemas.android.com/apk/res/android"
3. android:orientation="vertical"
4. android:layout_width="fill_parent"
5. android:layout_height="fill_parent"
6. >
7. <Button
8. android:text="启动Service"
9. android:id="@+id/startButton"
10. android:layout_width="fill_parent"
11. android:layout_height="wrap_content"
12. />
13. <Button
14. android:text="停止Service"
15. android:id="@+id/stopButton"
16. android:layout_width="fill_parent"
17. android:layout_height="wrap_content"
18. />
19. <Button
20. android:text="绑定Service"
21. android:id="@+id/bindButton"
22. android:layout_width="fill_parent"
23. android:layout_height="wrap_content"
24. />
25. <Button
26. android:text="解除绑定unbindService"
27. android:id="@+id/unbindButton"
28. android:layout_width="fill_parent"
29. android:layout_height="wrap_content"
30. />
31. </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:text="启动Service"		android:id="@+id/startButton"		android:layout_width="fill_parent"		android:layout_height="wrap_content"	/>		<Button		android:text="停止Service"		android:id="@+id/stopButton"		android:layout_width="fill_parent"		android:layout_height="wrap_content"	/>		<Button		android:text="绑定Service"		android:id="@+id/bindButton"		android:layout_width="fill_parent"		android:layout_height="wrap_content"	/>		<Button		android:text="解除绑定unbindService"		android:id="@+id/unbindButton"		android:layout_width="fill_parent"		android:layout_height="wrap_content"	/></LinearLayout>

不解释，看运行结果就会明白

（1）当点击“启动Servcie”会先弹出"onCreate"，然后弹出"onStart"的Toast，在LogCat中会看到先显示

的也是

onCreate

onStart

(2)点击“停止Service”按钮，会弹出onDestroy的Toast

LogCat中也会显示

onDestroy()

（3）点击"绑定Service"按钮，会弹出onCreate和onBind的Toast

LogCat中显示

onCreate

onBind

(4)点击“解除绑定Service”按钮，会弹出onDestroy的Toast,LogCat中也如此

下面是LogCat中显示的信息