Android实践--监測网络状态

	/**
	 * 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() {
                                     @Override
                                     public void onClick(DialogInterface dialog,int which) {
                                               Intent intent = null ;
                                               intent = newIntent(android.provider.Settings.ACTION_WIRELESS_SETTINGS);
                                               startActivity(intent);
                                     }
                     })
                    .setNegativeButton( "否" ,
                           new DialogInterface.OnClickListener() {
                                   @Override
                                    public void onClick(DialogInterface dialog, int which) {
                                               dialog.dismiss();
                                     }
                           }).show();
}