一、Native Service
1>什么是Native Service
使用JNI编写,在系统启动完成之前启动的系统级服务。
2>哪些服务是Native Service
ACCESSIBILITY_SERVICE
ACCOUNT_SERVICE
ACTIVITY_SERVICE
ALARM_SERVICE
AUDIO_SERVICE
CLIPBOARD_SERVICE
CONNECTIVITY_SERVICE
DEVICE_POLICY_SERVICE
DOWNLOAD_SERVICE
DROPBOX_SERVICE
INPUT_METHOD_SERVICE
KEYGUARD_SERVICE
LAYOUT_INFLATER_SERVICE
LOCATION_SERVICE
NOTIFICATION_SERVICE
POWER_SERVICE
SEARCH_SERVICE
SENSOR_SERVICE
STORAGE_SERVICE
TELEPHONY_SERVICE
UI_MODE_SERVICE
USB_SERVICE
VIBRATOR_SERVICE
WALLPAPER_SERVICE
WIFI_SERVICE
WINDOW_SERVICE
3>如何使用(示例)
1 //A. 怎么才能从资源文件中创建View呢? 2 //////////////////////////////////////////// 3 //调用LAYOUT_INFLATER_SERVICE,从资源中创建layout. 4 //////////////////////////////////////////// 5 LayoutInflater inflater= (LayoutInflater)context.getSystemService( 6 Context.LAYOUT_INFLATER_SERVICE); 7 View v = inflater.inflate(R.layout.list_item, null); 8 9 //B. 手机底座(Dock)是一种外设,一般分为Car Dock和Desk Dock 10 // 11 //当插入手机底座时,我们可能需要带给用户不同的体验。 12 //如:当插入Car Dock时,用户可能是将手机放在汽车的手机底座上,并很有可能正在开车途中。 13 //此时我们应将某些界面转入驾驶模式,如精简用户界面、加大图标及文字的显示等,以方便用户操作。 14 // 15 //那么,我们应当如何了解手机底座的插入状态呢? 16 // 17 //////////////////////////////////////////// 18 //使用UI_MODE_SERVICE查看当前手机的底座状态 19 //////////////////////////////////////////// 20 UiModeManager uiModeManager = (UiModeManager)getSystemService(Context.UI_MODE_SERVICE); 21 switch(uiModeManager.getCurrentModeType()) 22 case Configuration.UI_MODE_TYPE_NORMAL: 23 dockState.setText("no dock"); 24 break; 25 case Configuration.UI_MODE_TYPE_CAR: 26 dockState.setText("car dock mode"); 27 break; 28 case Configuration.UI_MODE_TYPE_DESK: 29 { 30 dockState.setText("desk dock mode"); 31 break; 32 }
4>Native Service的创建过程 (在系统启动完成之前)
(1) 获取Default Service Manager
(2) 创建NativeService并加入ServiceManager
(3) 启动线程池,开始处理Application传入的请求
二、Bound Service
1>什么是Bound Service
2>怎么使用
【Service】
1 //示例3.3.2 2 //BinderService.java 3 public class BinderService extends Service { 4 5 public interface ICallback{ 6 //在收到Message时被调用 7 public void onMessage(String msg); 8 } 9 private Set<ICallback> mCallbackList = new HashSet<ICallback>(); 10 11 public class ServiceBinder extends Binder{ 12 //将收到的Message通知所有的Callback 13 public void sendMessage(String msg){ 14 for (ICallback c : mCallbackList){ 15 c.onMessage(msg); 16 } 17 } 18 19 //将Callback添加到链表 20 public void RegisterCallback(ICallback callback){ 21 mCallbackList.add(callback); 22 } 23 24 //将Callback从链表中删除 25 public void UnregisterCallback(ICallback callback){ 26 mCallbackList.remove(callback); 27 } 28 } 29 private ServiceBinder mBinder = new ServiceBinder(); 30 @Override 31 public IBinder onBind(Intent arg0) { 32 return mBinder; 33 } 34 }
(1)创建Service并在AndroidManifest.xml中添加相关信息
(2)继承Binder类
(3)在OnBind()函数中返回Binder对象
【Client (如Activity)】
1 //示例3.3.3 2 //ServiceTestActivity.java 3 4 public class ServiceTestActivity extends Activity{ 5 private ServiceBinder mService = null; 6 7 //实现Service的Callback, 当收到Message时, 使用Toast将其显示出来 8 private ICallback mCallback = new ICallback(){ 9 @Override 10 public void onMessage(String msg) { 11 Toast.makeText(getApplication(), "Get message: " + msg, Toast.LENGTH_LONG).show(); 12 } 13 }; 14 15 //在OnCreate时BindService 16 //但需注意的时,此时Service还没有被绑定,而需要等到onServiceConnected执行时才能使用。 17 @Override 18 public void onCreate(Bundle savedInstanceState) { 19 super.onCreate(savedInstanceState); 20 bindService(new Intent(this, BinderService.class), mConnection, BIND_AUTO_CREATE); 21 } 22 23 //在onDestroy时unbindService,mService不应再被使用 24 @Override 25 protected void onDestroy() { 26 if (mService != null){ 27 mService.UnregisterCallback(mCallback); 28 unbindService(mConnection); 29 } 30 31 super.onDestroy(); 32 } 33 34 private ServiceConnection mConnection = new ServiceConnection() { 36 //Service绑定完成 37 @Override 38 public void onServiceConnected(ComponentName className, 39 IBinder service) { 40 mService = (ServiceBinder) service; 41 mService.RegisterCallback(mCallback); 42 mService.sendMessage("Service Connected!"); 43 } 45 //Service已断开 46 @Override 47 public void onServiceDisconnected(ComponentName className) { 48 mService = null; 49 } 50 }; 51 }
(1)调用BindSerive
(2)实现ServiceConnection
(3)在onServiceConnected中保存由Service提供的Binder对象
3>如何与Client交互
(1)编写ICallback接口
(2)在Service的Binder类中实现RegisterCallback和UnregisterCallback
(3)在Client中调用RegisterCallback
4>分类
【Local Service】
只能被当前进程调用 参考:示例3.3.2, 3.3.3
【Remote Service】
可以被其它进程调用的Service, 可用于进程间的数据共享。
1>Service
(1) 创建AIDL文件
1 (2) //示例3.3.4 2 (3) //IRemoteService.aidl 4 (5) package com.demo.service; 6 (7) /* 7 (8) * 在AIDL文件中只能使用一下类型的数据: 8 (9) * 9 (10) * 基础类型(int, long, boolean等) 10 (11) * String 11 (12) * CharSequence 12 (13) * List 13 (14) * Map 14 (15) */ 15 (16) interface IRemoteService { 16 (17) int getVersion();(18) }
(2) 在Service中实现AIDL中的接口,并返回给Client
1 //示例3.3.5 2 //RemoteService.java 3 public class RemoteService extends Service { 4 private static final int VERSION = 1492; 5 public class RemoteBinder extends IRemoteService.Stub{ 6 @Override 7 public int getVersion() throws RemoteException { 8 return VERSION; 9 } 10 } 11 private RemoteBinder mBinder = new RemoteBinder(); 12 @Override 13 public IBinder onBind(Intent intent) { 14 return mBinder; 15 } 16 }
(3) 在AndroidManifest中添加相关信息
1 //示例3.3.6 2 <serviceandroid:name="RemoteService"> 3 <intent-filter> 4 <actionandroid:name="com.demo.service.action.REMOTE_SERVICE"/> 5 </intent-filter> 6 </service>
2>Client
(1) 复制AIDL文件至相应的目录
(2) 编译项目,Eclipse会自动生成相关的服务接口类
(3) 调用bindService绑定服务
1 //示例3.3.7 2 //注意:这里应该使用远程服务的action,而不能再直接用class 3 bindService(newIntent("com.demo.service.action.REMOTE_SERVICE"), mConnection,BIND_AUTO_CREATE); 4 //ServiceConnection 5 private ServiceConnection mConnection = new ServiceConnection() { 6 @Override 7 public void onServiceConnected(ComponentName name, IBinder service) { 8 //注意这里应该使用asInterface方法进行转换 9 mService = IRemoteService.Stub.asInterface(service);//(IRemoteService)service; 10 Log.e("Alfred", "onServiceConnected" + mService); 11 try { 12 Log.e("Alfred", "version: " + mService.getVersion()); 13 } catch (RemoteException e) { 14 e.printStackTrace(); 15 } 16 } 17 @Override 18 public void onServiceDisconnected(ComponentName name) { 19 mService = null; 20 } 21 };
三、什么时候使用Intent Service, 什么时候使用Bound Service
通常,在只需要Service执行一个简单的请求,只需要传递参数,而不在乎返回值、无需和Service有交互操作时,我们使用
IntentService。
若我们需要知道Service的处理结果,或者和Service之间有交互操作(一般通过Callback实现)时,我们使用Bound Service.