/*** 检查WIFI是否连接* * @author Ysjian* @date 2014-5-9* @return 假设连接了返回true，否则返回false*/public boolean isWifiConnected() {ConnectivityManager connectivityManager = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);NetworkInfo wifiInfo = connectivityManager.getNetworkInfo(ConnectivityManager.TYPE_WIFI);return wifiInfo != null;}/*** 检查手机网络(4G/3G/2G)是否连接* * @author Ysjian* @date 2014-5-9* @return 假设连接了返回true，否则返回false*/public boolean isMobileNetworkConnected() {ConnectivityManager connectivityManager = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);NetworkInfo mobileNetworkInfo = connectivityManager.getNetworkInfo(ConnectivityManager.TYPE_MOBILE);return mobileNetworkInfo != null;}/*** 检查是否有可用网络* * @author Ysjian* @date 2014-5-9* @return 存在WIFI和手机数据随意可用网络返回true。否则返回false*/public boolean hasActivityNetwork() {ConnectivityManager connectivityManager = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);return connectivityManager.getActiveNetworkInfo() != null;}

if (!hasActivityNetwork()) {AlertDialog.Builder builder = new AlertDialog.Builder(this );builder. setTitle( "没有可用的网络" ).setMessage( "是否对网络进行设置?" ).setPositiveButton( "是" ,new DialogInterface.OnClickListener() {@Overridepublic void onClick(DialogInterface dialog,int which) {Intent intent = null ;intent = newIntent(android.provider.Settings.ACTION_WIRELESS_SETTINGS);startActivity(intent);}}).setNegativeButton( "否" ,new DialogInterface.OnClickListener() {@Overridepublic void onClick(DialogInterface dialog, int which) {dialog.dismiss();}}).show();
}

文章来源：http://blog.csdn.net/ysjian_pingcx/article/details/25461053