Android 判断网络是否可用

/**
 * 判断网络连接是否可用（返回true表示网络可用，false为不可用）
 */
public static boolean checkNetworkAvailable(Activity activity) {
    boolean isNetUsable = false;
    ConnectivityManager manager = (ConnectivityManager)
            activity.getSystemService(Context.CONNECTIVITY_SERVICE);
    NetworkCapabilities networkCapabilities =
            manager.getNetworkCapabilities(manager.getActiveNetwork());
    if (networkCapabilities != null) {
        isNetUsable = networkCapabilities.hasCapability(NetworkCapabilities.NET_CAPABILITY_VALIDATED);
    }
    return isNetUsable;
}