控制WebRequest代理

private void ProxySetting(WebRequest request)
        {
            WebProxy proxy = WebProxy.GetDefaultProxy();//获取IE缺省设置 //如果缺省设置为空，则有可能是根本不需要代理服务器，如果此时配置文件中也未配置则认为不需Proxy 
            if (proxy.Address == null)//按配置文件创建Proxy 地置 
            {
                string address = "http://"+ConfigurationUtil.ProxyAddress + ":" + ConfigurationUtil.ProxyPort;
                proxy.Address = new Uri(address);
            }
           
            if (proxy.Address != null)//如果地址为空，则不需要代理服务器
            {
                proxy.Credentials = new NetworkCredential(ConfigurationUtil.UserName, ConfigurationUtil.Password);//从配置封装参数中创建
                request.Proxy = proxy;//赋予 request.Proxy 
            }
        }

if (Convert.ToBoolean(ConfigurationUtil.IsProxy))
{
     ProxySetting(request);
}

internal class ConfigurationUtil
    {
        public static string IsProxy
        {
            get
            {
                if (string.IsNullOrEmpty(_IsProxy))
                {
                    _IsProxy = ConfigurationManager.AppSettings["IsProxy"];
                }
                return _IsProxy;
            }
        }

        public static string ProxyAddress
        {
            get
            {
                if (string.IsNullOrEmpty(_proxyAddress))
                {
                    _proxyAddress = ConfigurationManager.AppSettings["ProxyAddress"];
                }
                return _proxyAddress;
            }
        }

        public static string ProxyPort
        {
            get
            {
                if (string.IsNullOrEmpty(_proxyPort))
                {
                    _proxyPort = ConfigurationManager.AppSettings["ProxyPort"];
                }
                return _proxyPort;
            }
        }

        public static string UserName
        {
            get
            {
                if (string.IsNullOrEmpty(_userName))
                {
                    _userName = ConfigurationManager.AppSettings["UserName"];
                }
                return _userName;
            }
        }

        public static string Password
        {
            get
            {
                if (string.IsNullOrEmpty(_password))
                {
                    _password = ConfigurationManager.AppSettings["Password"];
                }
                return _password;
            }
        }

        private static string _proxyAddress;
        private static string _proxyPort;
        private static string _userName;
        private static string _password;
        private static string _IsProxy;
    }

<?xml version="1.0" encoding="utf-8"?>
<appSettings>
  <add key="IsProxy" value="False"/>
  <add key="ProxyAddress" value="192.168.1.222"/>
  <add key="ProxyPort" value="8080"/>
  <add key="UserName" value="xxxx"/>
  <add key="Password" value="123"/>
</appSettings>