一个以流方式读取文件的方式,可以设置超时时间

代码

using System;
using System.Xml;
using System.Text;
using System.Text.RegularExpressions;
using System.Net;
using System.IO;
 
namespace blogdata.nms_common
{
       ///<summary>
       ///定义获得数据流接口
       ///</summary>
       public interface IRequestable
       {
              Stream GetStream(string requestUrl);
       }
       ///<summary>
       /// Http 的摘要说明
       ///</summary>
       public class Http : IRequestable
       {
              ///<summary>
              ///设置请求的延时时间，以秒为单位
              ///</summary>
              private int mTimeOut = 1;
              ///<summary>
              /// ̉异常错误信息
              ///</summary>
              public string errorMessage;
              public string ErrorMessage
              {
                     get {return this.errorMessage;}
              }
              ///<summary>
              ///构造函数
              ///</summary>
              public Http(int timeOut)
              {
                     this.mTimeOut = timeOut * 1000;   
              }
              ///<summary>
              ///用方法隐藏成员
              ///</summary>
              ///<param name="timeOut"></param>
              ///<returns></returns>
              public static Http GetIntance(int timeOut)
              {
                     return new Http(timeOut);
              }
              ///<summary>
              ///重载用方法隐藏成员，默认为1秒
              ///</summary>
              public static Http GetIntance()
              {
                     return new Http(1);
              }
 
              #region IRequestface ³ÉÔ±
              ///<summary>
              ///实现接口
              ///</summary>
              ///<param name="requestUrl"></param>
              ///<returns></returns>
              public Stream GetStream(string requestUrl)
              {
                     return GetStream(requestUrl,null);
              }
              ///<summary>
              ///重载接口
              ///</summary>
              ///<param name="requestUrl"></param>
              ///<param name="postData"></param>
              ///<returns></returns>
              public Stream GetStream(string requestUrl,byte[] postData)
              {
                     if (requestUrl == null || requestUrl.Length == 0) return null;
                     //判断有没有http://头
                     string httpHead = requestUrl.Substring(0,7);
                     if (httpHead.ToLower() != "http://") return null;
                     WebRequest wrq = WebRequest.Create(requestUrl);
                     wrq.Timeout = this.mTimeOut; //请求的时间，以秒为单位
                            if (postData != null)
                            {
                                   wrq.Method = "POST";
                                   wrq.ContentType =
                                          "application/x-www-form-urlencoded";
                                   wrq.ContentLength = postData.Length;
                                   Stream rs = wrq.GetRequestStream();
                                   rs.Write(postData,0,postData.Length);
                                   rs.Close();
                                   rs = null;
                            }
                     try
                     {
                            WebResponse wrp = wrq.GetResponse();
                            Stream res = wrp.GetResponseStream();
                            if(res != null) return res;
                     }
                     catch (WebException we)
                     {
                            //调试使用，也可以转化为流输出,我没有转化
                            this.errorMessage = we.Message;
                     }
                     return null;
              }
              #endregion
       }
}

调用方法：
Stream gets = Http.GetIntance(timeout).GetStream(url);
//这里可以判断一下流
if (gets == null)
          Response.Write("error");
else
{
          //由于有些域名的访问是返回了北京宽带网或者其他的错误信息。因此不能捕获异常，结果为：流 !=null 通过读出流看一下数据，就明白了。
         Encoding encode =
         System.Text.Encoding.GetEncoding("gb2312");
         //读流
         StreamReader reader = new StreamReader(gets, encode);
         string str = reader.ReadToEnd().ToString();
         Response.Write(str);
}
注：
1、这里就不要捕获异常了。如果返回的为：null则就是发生了异常。因为我在类里面
已经处理异常了。
2、Url必须为完整的路径
即：带有http://标志，否则不能访问