/**
 * 检测网络是否连接
 * 
 * @return
 */
private boolean isNetworkAvailable() {
  // 得到网络连接信息
  ConnectivityManager manager = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
  // 去进行判断网络是否连接
  if (manager.getActiveNetworkInfo() != null) {
    return manager.getActiveNetworkInfo().isAvailable();
  }
  return false;
}

/* @author suncat
 * @category 判断是否有外网连接（普通方法不能判断外网的网络是否连接，比如连接上局域网）
 * @return
 */ 
public static final boolean ping() { 

  String result = null; 
  try { 
      String ip = "www.baidu.com";// ping 的地址，可以换成任何一种可靠的外网 
      Process p = Runtime.getRuntime().exec("ping -c 3 -w 100 " + ip);// ping网址3次 
      // 读取ping的内容，可以不加 
      InputStream input = p.getInputStream(); 
      BufferedReader in = new BufferedReader(new InputStreamReader(input)); 
      StringBuffer stringBuffer = new StringBuffer(); 
      String content = ""; 
      while ((content = in.readLine()) != null) { 
          stringBuffer.append(content); 
      } 
      Log.d("------ping-----", "result content : " + stringBuffer.toString()); 
      // ping的状态 
      int status = p.waitFor(); 
      if (status == 0) { 
          result = "success"; 
          return true; 
      } else { 
          result = "failed"; 
      } 
  } catch (IOException e) { 
      result = "IOException"; 
  } catch (InterruptedException e) { 
      result = "InterruptedException"; 
  } finally { 
      Log.d("----result---", "result = " + result); 
  } 
  return false;
}