ConnectivityManager（三）

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关于Android WiFi，我写了5篇文章，讲解了在配置WiFi中用到的知识

WifiManager、ScanResult（一）
WifiInfo（二）
ConnectivityManager（三）
NetworkInfo和NetworkInfo.State（四）
WifiManager、WifiInfo、WifiConfiguration集成类（五）

代码示例来自http://www.cnblogs.com/ywtk/p/3876076.html

ConnectivityManager
android.net.ConnectivityManager
1、用于管理与网络连接相关的操作用于查询网络连接类型和状态
2、网络状态发生改变时通知应用。

主要功能：
The primary responsibilities of this class are to:
1、Monitor network connections (Wi-Fi, GPRS, UMTS, etc.)
2、Send broadcast intents when network connectivity changes
3、Attempt to “fail over” to another network when connectivity to a network is lost
4、Provide an API that allows applications to query the coarse-grained or fine-grained state of the available networks
5、Provide an API that allows applications to request and select networks for their data traffic

• 通过调用下面函数获得ConnectivityManager的实例：Context.getSystemService(Context.CONNECTIVITY_SERVICE)。

ConnectivityManager cm = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);

• 网络改变时发送广播，使用CONNECTIVITY_ACTION注册Receiver接收广播

networkBroadcast = new NetworkBroadcast();networkfilter = new IntentFilter (ConnectivityManager . CONNECTIVITY_ACTION);registerReceiver(networkBroadcast, networkfilter);

• NetworkInfo getNetworkInfo(int networkType)
  Returns connection status information about a particular network type. 查询连接状态的信息关于指定的网络模式

  • NetworkInfo.State getState()
    Reports the current coarse-grained state of the network.
    这个是NetworkInfo 的方法，粗粒度报告当前的网络连接状态，这里的粗粒度，就是枚举类型State里的几种状态

State wifiState = cm.getNetworkInfo(ConnectivityManager.TYPE_WIFI).getState();