1.WifiManagr (管理Wifi的)
WifiManager wm=(WifiManager)getSystemService(Context.WIFI_SERVICE);
2. ActivityManager (与所有在系统上运行的Acctivity都有交互)
ActivityManager am = (ActivityManager)getSystemService(Context.ACTIVITY_SERVICE);
3. PackageManager (Class for retrieving various kinds of information related to the application packages that are currently installed on the device.)
PackageManager pm=(PackageManager)getPackageManager();
4. ConnectivityManager (查询网络连接状态的类，它也能提醒程序当网络改变的时候)(感觉用处不大)
ConnectivityManager cm=(ConnectivityManager)getSystemService(Context.CONNECTIVITY_SERVICE).
5. WindowManager (The interface that apps use to talk to the window manager.)(可以靠他得到屏幕信息)
WindowManager wm=(WindowManager)getSystemService(Context.WINDOW_SERVICE);
6. DownloadManager (The download manager is a system service that handles long-running HTTP downloads)
DownloadManager dm=(DownloadManager)getSystemService(Context.DOWNLOAD_SERVICE);
7. NotificationManager (通知栏提醒控制类)
NotificationManager nm=(NotificationManager)getSystemService(NOTIFICATION_SERVICE);
8.ClipboardManager (复制黏贴控制类)
ClipboardManager clipboardManager = (ClipboardManager )getSystemService(Context.CLIPBOARD_SERVICE);