基础连接已经关闭解决方案

最新推荐文章于 2025-05-20 11:08:01 发布

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最新推荐文章于 2025-05-20 11:08:01 发布

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分类专栏： Winform (C#) 可用类库、方法、DLL等

本文链接：https://blog.youkuaiyun.com/keenweiwei/article/details/8871272

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本文介绍了一种解决网页抓取过程中遇到的基础连接已关闭错误的方法，通过使用HttpWebRequest替代WebRequest，并设置UserAgent、KeepAlive等属性，成功避免了连接关闭的问题。

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       /// <summary>
        /// iEncode=1- gb2312; 2- UTF8
       /// </summary>
       /// <param name="url"></param>
       /// <param name="iEncode"></param>
       /// <returns></returns>
       public static string GetPageInfo(String url, int iEncode = 1)
       {
           WebResponse wr_result = null;
           StringBuilder txthtml = new StringBuilder();
           try
           {
               //WebRequest wr_req = WebRequest.Create(url);
               //wr_result = wr_req.GetResponse();

               HttpWebRequest wr_req = WebRequest.Create(url) as HttpWebRequest;
               wr_req.UserAgent = "Mozilla/4.0   (compatible;   MSIE   6.0;   Windows   NT   5.1;   SV1;   .NET   CLR  4.0) ";
               //wr_req.UserAgent = "Mozilla/4.0   (compatible;   MSIE   6.0;   Windows   NT   5.1;   SV1;   .NET   CLR  2.0.50727) ";
               wr_req.KeepAlive = false;
               wr_req.ProtocolVersion = HttpVersion.Version10;
               wr_result = wr_req.GetResponse();
              
               Stream ReceiveStream = wr_result.GetResponseStream();
               Encoding encode = System.Text.Encoding.GetEncoding("gb2312");

               if (iEncode == 1)
               {
                   encode = System.Text.Encoding.GetEncoding("gb2312");
               }
               else if (iEncode == 2)
               {
                   encode = Encoding.UTF8;
               }

               //Encoding encode = Encoding.Unicode;
               //Encoding encode = Encoding.UTF8;

               StreamReader sr = new StreamReader(ReceiveStream, encode);
               if (true)
               {
                   Char[] read = new Char[256];
                   int count = sr.Read(read, 0, 256);
                   while (count > 0)
                   {
                       String str = new String(read, 0, count);
                       txthtml.Append(str);
                       count = sr.Read(read, 0, 256);
                   }
               }
           }
           catch (Exception ex)
           {
               txthtml.Append("err");
           }
           finally
           {
               if (wr_result != null)
               {
                   wr_result.Close();
               }
           }
           return txthtml.ToString();
       }

用这2行

WebRequest wr_req = WebRequest.Create(url);
wr_result = wr_req.GetResponse();

就会出现基础连接已经关闭的错误

改用

HttpWebRequest wr_req = WebRequest.Create(url) as HttpWebRequest;
wr_req.UserAgent = "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; .NET CLR 4.0) ";
//wr_req.UserAgent = "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; .NET CLR 2.0.50727) ";
wr_req.KeepAlive = false;
wr_req.ProtocolVersion = HttpVersion.Version10;
wr_result = wr_req.GetResponse();

就可以了.

参考：

http://blog.youkuaiyun.com/flyingdream123/article/details/6766487

http://q.cnblogs.com/q/8593/