Android——getSystemService

android的后台运行在很多service，它们在系统启动时被SystemServer开启，支持系统的正常工作，比如MountService监 听是否有SD卡安装及移除，ClipboardService提供剪切板功能，PackageManagerService提供软件包的安装移除及查看等 等，应用程序可以通过系统提供的Manager接口来访问这些Service提供的数据。

 

    getSystemService是Android很重要的一个API，它是Activity的一个方法，根据传入的NAME来取得对应的Object，然后转换成相应的服务对象。以下介绍系统相应的服务。

 

           传入的Name           |           返回的对象              |         说明

• WINDOW_SERVICE                      WindowManager                    管理打开的窗口程序
• LAYOUT_INFLATER_SERVICE    
       
    LayoutInflater  
       
       
      取得xml里定义的view
• ACTIVITY_SERVICE    
       
       
     ActivityManager
       
       
     
   管理应用程序的系统状态
• POWER_SERVICE    
       
       
       
  PowerManger    
       
       
       电源的服务
• ALARM_SERVICE    
       
       
       
  AlarmManager    
       
       
      闹钟的服务
• NOTIFICATION_SERVICE    
       
     
   NotificationManager  
       
     
   状态栏的服务
• KEYGUARD_SERVICE    
       
       
     KeyguardManager
       
       
     
   键盘锁的服务
• LOCATION_SERVICE    
       
       
     LocationManager
       
       
     
   位置的服务，如GPS
• SEARCH_SERVICE    
       
       
     
   SearchManager  
       
       
       搜索的服务
• VEBRATOR_SERVICE    
       
       
     Vebrator  
       
       
       
      手机震动的服务
• CONNECTIVITY_SERVICE    
       
     
   Connectivity  
       
       
       
  网络连接的服务
• WIFI_SERVICE    
       
       
       
   WifiManager    
       
       
     
   Wi-Fi服务
• TELEPHONY_SERVICE    
       
       
    TeleponyManager  
       
       
     电话服务

 

 

Currently available names are:

• WINDOW_SERVICE ("window") 
  The top-level window manager in which you can place custom windows.
  The returned object is a WindowManager.
• LAYOUT_INFLATER_SERVICE ("layout_inflater")
  A LayoutInflater for inflating layout resources in this
  context.
• ACTIVITY_SERVICE ("activity")
  A ActivityManager for interacting with the global activity state of
  the system.
• POWER_SERVICE ("power")
  A PowerManager for controlling power
  management.
• ALARM_SERVICE ("alarm")
  A AlarmManager for receiving intents at the time of your
  choosing.
• NOTIFICATION_SERVICE ("notification")
  A NotificationManager for informing the user of background
  events.
• KEYGUARD_SERVICE ("keyguard")
  A KeyguardManager for controlling keyguard.
• LOCATION_SERVICE ("location")
  A LocationManager for controlling location (e.g., GPS)
  updates.
• SEARCH_SERVICE ("search")
  A SearchManager for handling search.
• VIBRATOR_SERVICE ("vibrator")
  A Vibrator for interacting with the vibrator
  hardware.
• CONNECTIVITY_SERVICE ("connection")
  A ConnectivityManager for handling management of network
  connections.
• WIFI_SERVICE ("wifi")
  A WifiManager for management of Wi-Fi
  connectivity.
• INPUT_METHOD_SERVICE ("input_method")
  An InputMethodManager for management of input
  methods.
• UI_MODE_SERVICE ("uimode")
  An UiModeManager for controlling UI modes.
• DOWNLOAD_SERVICE ("download")
  A DownloadManager for requesting HTTP downloads

 

Note: System services obtained via this API may be closely
associated with the Context in which they are obtained from. In
general, do not share the service objects between various different
contexts (Activities, Applications, Services, Providers,
etc.)

 

一个例子：

在android 获取手机信息的时候用到这样一段代码：

public class BasicInfo {

public String
getPhoneNumber()

{

//
获取手机号 MSISDN，很可能为空

TelephonyManager tm =
(TelephonyManager) getSystemService(Context.TELEPHONY_SERVICE);

StringBuffer
inf = new StringBuffer();

switch(tm.getSimState()){
//getSimState()取得sim的状态  有下面6中状态

case
TelephonyManager.SIM_STATE_ABSENT :inf.append("无卡");return
inf.toString();

case
TelephonyManager.SIM_STATE_UNKNOWN :inf.append("未知状态");return
inf.toString();

case
TelephonyManager.SIM_STATE_NETWORK_LOCKED
:inf.append("需要NetworkPIN解锁");return inf.toString();

case
TelephonyManager.SIM_STATE_PIN_REQUIRED
:inf.append("需要PIN解锁");return inf.toString();

case
TelephonyManager.SIM_STATE_PUK_REQUIRED
:inf.append("需要PUK解锁");return inf.toString();

case
TelephonyManager.SIM_STATE_READY :break;

}

String phoneNumber =
tm.getLine1Number();

return
phoneNumber;

}

在另外一个activity类里面调用的时候 总是出现进程关闭 无法获取手机信息。后来发现

getSystemService这个方法基于context,只有存在TextView控件的窗体中这个方法才会被激活~

于是：

1. 给BasicInfo
添加一个带参数Context的构造函数：

public BasicInfo (Context context)

{

this.context =
context;

}

2. getPhoneNumber()函数里面改成：

context.getSystemService(Context.TELEPHONY_SERVIC);

3. 在调用类里面 BasicInfo bi = new
BasicInfo(this);

bi.getPhoneNumber();

引自：http://blog.sina.com.cn/s/blog_7cb2c5d50101c26t.html