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获取网络连接状态

随着3G和Wifi的推广，越来越多的Android应用程序需要调用网络资源，检测网络连接状态也就成为网络应用程序所必备的功能。

Android平台提供了ConnectivityManager  类，用于网络连接状态的检测。

Android开发文档这样描述ConnectivityManager 的作用：

 

Class that answers queries about the state of network connectivity. It also notifies applications when network connectivity changes. Get an instance of this class by callingContext.getSystemService(Context.CONNECTIVITY_SERVICE).

The primary responsibilities of this class are to:

Monitor network connections (Wi-Fi, GPRS, UMTS, etc.)

Send broadcast intents when network connectivity changes

Attempt to "fail over" to another network when connectivity to a network is lost

Provide an API that allows applications to query the coarse-grained or fine-grained state of the available networks

下面这个简单的例子 checkNetworkInfo() 说明了如何编程获取Android手机的当前网络状态

private void checkNetworkInfo()
{
        ConnectivityManager conMan = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);

        //mobile 3G Data Network
        State mobile = conMan.getNetworkInfo(ConnectivityManager.TYPE_MOBILE).getState();
        txt3G.setText(mobile.toString()); //显示3G网络连接状态
        //wifi
        State wifi = conMan.getNetworkInfo(ConnectivityManager.TYPE_WIFI).getState();
        txtWifi.setText(wifi.toString()); //显示wifi连接状态
}

private void checkNetworkInfo()
{
        ConnectivityManager conMan = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);

        //mobile 3G Data Network
        State mobile = conMan.getNetworkInfo(ConnectivityManager.TYPE_MOBILE).getState();
        txt3G.setText(mobile.toString());
        //wifi
        State wifi = conMan.getNetworkInfo(ConnectivityManager.TYPE_WIFI).getState();
        txtWifi.setText(wifi.toString());
        
        //如果3G网络和wifi网络都未连接，且不是处于正在连接状态 则进入Network Setting界面 由用户配置网络连接
        if(mobile==State.CONNECTED||mobile==State.CONNECTING)
            return;
        if(wifi==State.CONNECTED||wifi==State.CONNECTING)
            return;
        
        
        startActivity(new Intent(Settings.ACTION_WIRELESS_SETTINGS));//进入无线网络配置界面
        //startActivity(new Intent(Settings.ACTION_WIFI_SETTINGS)); //进入手机中的wifi网络设置界面
        
}

运行结果(关闭3G及wifi网络连接的状态下)，程序转入无线网络配置界面

startActivity(new Intent(Settings.ACTION_WIRELESS_SETTINGS));//进入无线网络配置界面

startActivity(new Intent(Settings.ACTION_WIFI_SETTINGS)); //直接进入手机中的wifi网络设置界面

则直接进入手机中的wifi网络设置界面