判断网络状态

public static boolean isNetworkAvailable(Context context) {
    ConnectivityManager connectivity = (ConnectivityManager) context
            .getSystemService(Context.CONNECTIVITY_SERVICE);
    if (connectivity != null) {
        NetworkInfo info = connectivity.getActiveNetworkInfo();
        if (info != null && info.isConnected())
        {
            // 当前网络是连接的
            if (info.getState() == NetworkInfo.State.CONNECTED)
            {
                // 当前所连接的网络可用
                return true;
            }
        }
    }
    return false;
}
判断时注意在Manifests中添加权限

<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>
<uses-permission android:name="android.permission.INTERNET"/>