判断网络是否连接工具类

/**
 * Created by a on 2014/5/18.
 *
 * 和网络相关的工具类
 *
 * isConnected(Context context) 判断网络是否连接
 * isWifi(Context context) 判断是否是wifi连接
 * openSetting(Activity activity) 打开网络设置界面
 *
 * @author zhengjiao
 *
 */
public class NetUtils {


    private NetUtils()
    {
        /* cannot be instantiated */
        throw new UnsupportedOperationException("cannot be instantiated");
    }


    /**
     * 判断网络是否连接
     *
     * @param context
     * @return
     */
    public static boolean isConnected(Context context)
    {


        ConnectivityManager connectivity = (ConnectivityManager) context
                .getSystemService(Context.CONNECTIVITY_SERVICE);


        if (null != connectivity)
        {


            NetworkInfo info = connectivity.getActiveNetworkInfo();
            if (null != info && info.isConnected())
            {
                if (info.getState() == NetworkInfo.State.CONNECTED)
                {
                    return true;
                }
            }
        }
        return false;
    }


    /**
     * 判断是否是wifi连接
     */
    public static boolean isWifi(Context context)
    {
        ConnectivityManager cm = (ConnectivityManager) context .getSystemService(Context.CONNECTIVITY_SERVICE);


        if (cm == null)
            return false;


        return cm.getActiveNetworkInfo().getType() == ConnectivityManager.TYPE_WIFI;


    }


    /**
     * 打开网络设置界面
     */
    public static void openSetting(Activity activity)
    {
        Intent intent = new Intent("/");
        ComponentName cm = new ComponentName("com.android.settings","com.android.settings.WirelessSettings");
        intent.setComponent(cm);
        intent.setAction("android.intent.action.VIEW");
        activity.startActivityForResult(intent, 0);
    }


}