公共代码参考（ConnectivityManager）

package com.fredric.util;

import android.content.Context;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;
import android.net.NetworkInfo.State;

/*-
 * 网络工具类
 */

public class NetUtils {

    //判断网络是否连接
    public static boolean isConnected(Context context){
        
        ConnectivityManager connectivity = (ConnectivityManager) context  
                .getSystemService(Context.CONNECTIVITY_SERVICE);
        //WLAN五种状态
        //1，显示连接已保存，但标题栏没有，即没有实质连接上，输出为：not connect， available
        //2，显示连接已保存，标题栏也有已连接上的图标，            输出为：connect， available
        //3，选择不保存后                                                                     输出为：not connect， available
        //4，选择连接，在正在获取IP地址时                                     输出为：not connect， not available
        //5，连接上后                                                                           输出为：connect， available
        if(null != connectivity){
            NetworkInfo info = connectivity.getActiveNetworkInfo();
            if(null != info && info.isConnected()){
                return true;
            }
        }
        
        return false;
    }
    
    //判断是否wifi连接
    public static boolean isWifiConnect(Context context){
        ConnectivityManager connectivity = (ConnectivityManager) context  
                .getSystemService(Context.CONNECTIVITY_SERVICE);
        if(null != connectivity){
            State state = connectivity
                    .getNetworkInfo(ConnectivityManager.TYPE_WIFI).getState();
            if(state == State.CONNECTED){
                return true;
            }
        }
        
        return false;        
    }
    
    //判断GPRS是否连接
    public static boolean isGPRSConnect(Context context){
        ConnectivityManager connectivity = (ConnectivityManager) context  
                .getSystemService(Context.CONNECTIVITY_SERVICE);
        if(null != connectivity){
            State state = connectivity
                    .getNetworkInfo(ConnectivityManager.TYPE_MOBILE).getState();
            if(state == State.CONNECTED){
                return true;
            }
        }
        
        return false;        
    }
}