C# post数据时 出现如下错误: System.Net.WebException: 操作超时

net(客户端)调用IIS(服务端)出现503后，就报操作超时错误

问题描述：
服务端环境：
IIS

客户端环境：
windowsxp + iis + .net


调用时出现如下错误:
System.Net.WebException: 远程服务器返回错误: (503) 服务器不可用。
在 System.Net.HttpWebRequest.GetResponse()
在 TestWebRequest.WebMessage.SendRequest(Byte[] data, String urlStr)

接着就出现如下错误：

System.Net.WebException: 操作超时
在 System.Net.HttpWebRequest.GetRequestStream()

最后一直是这个错误

System.Net.WebException: 操作超时
在 System.Net.HttpWebRequest.GetRequestStream()

当服务器恢复正常时，访问已经是200时，这个线程还是返回操作超时，经过N多测试，最后如下一行完美解决：

myRequest.ServicePoint.Expect100Continue = false;

public byte[] SendRequest(byte[] data, string urlStr)
2{
3try
4{
5 Stream streamSend = null;
6 HttpWebRequest myRequest = (HttpWebRequest)WebRequest.Create(urlStr);
7 myRequest.Method = "POST";
8 myRequest.ContentType = "text/xml";
9 myRequest.Accept = "*/*";
10 myRequest.Timeout = 2000;
11 myRequest.UserAgent = "Mozilla-Firefox-Spider(Wenanry)";
12 myRequest.ContentLength = data.Length;
13//这个在Post的时候，一定要加上，如果服务器返回错误，他还会继续再去请求，不会使用之前的错误数据，做返回数据
14 myRequest.ServicePoint.Expect100Continue = false;
15
16 HttpRequestCachePolicy noCachePolicy = new HttpRequestCachePolicy(HttpRequestCacheLevel.NoCacheNoStore);
17 myRequest.CachePolicy = noCachePolicy;
18
19try
20{
21 streamSend = myRequest.GetRequestStream();
22 streamSend.Write(data, 0, data.Length);
23 streamSend.Close();
24 }
25catch (WebException wex)
26{
27 log.Debug("WebException=" + wex.ToString() + ",wex.Status=" + wex.Status);
28if (streamSend != null)
29 streamSend.Close();
30 streamSend = null;
31 myRequest = null;
32return null;
33 }
34catch (Exception ex)
35{
36 log.Debug("GetRequestStream=" + ex.ToString());
37if (streamSend != null)
38 streamSend.Close();
39 myRequest = null;
40return null;
41 }
42
43byte[] byteArr = new byte[256];
44 Stream streamRequest = null;
45try
46{
47 streamRequest = myRequest.GetResponse().GetResponseStream();
48 }
49catch (Exception httpex)
50{
51 log.Debug("SendRequest=" + httpex.ToString());
52if (streamRequest != null)
53 streamRequest.Close();
54 myRequest = null;
55return null;
56 }
57 Bytes bytes = new Bytes();
58int count = streamRequest.Read(byteArr, 0, 256);
59while (count > 0)
60{
61 bytes.writeByteArr(Bytes.byteSub(byteArr, 0, count));
62 count = streamRequest.Read(byteArr, 0, 256);
63 }
64 streamRequest.Close();
65return bytes.getByte;
66 }
67catch (Exception eee)
68{
69 log.Debug("eee=" + eee.ToString() + eee.Source + eee.StackTrace);
70 }
71return null;
72 }