C#实现HTTP POST请求的一个问题

CrazyTdkgn

鄙人学生狗，想编个程序从学校网站爬取所有本校学生的基本个人信息，但是处理一个post请求遇到了问题，求各位大神指点。




如图这么一个局部页面，当我输入学号并点击查询的时候，能用IE捕获一个HTTP请求


用学号20131002做测试的时候，捕获的请求正文如下

__VIEWSTATE=HLl7RXFL6YpOPaz9Ks92d5pfyHlcO9h4M1myiZ4CDMijHAADaC%2FClM8CawE2W%2F9dJNN2HG%2FQnZ5k0dW6HM%2FE%2Bn%2BMAosdT%2Bst1MsJsCTHu4o9qs5K%2BaiygQWBsoM1bcGTWq7iWnQoo%2FTc1FsnVSIbTXlAhhf%2B2U%2BKGkE1vpxDMFCyxFNHQb1XWidAYRmgxq7Yef5dYhEU4vd%2Fyt8KJ00WWuWNgTIDg%2BmIpO%2FK9KiRz%2Fes1VUpSJQrrVIrVnlmmQKA5n3yrdt3EPXk%2FHIt44TD%2BmNBglXZ5aaRNt9LXrlgNfYeXHEmSWDGNI29sJXc1iMBOjFu%2BtV62oyqnb%2FKLoOEFJz0tvvS2vZ57kTeUn596Krhilr2Y0WKk1DSHJ10xpVS5h5SYWRidzligH7f%2BV001UVjhopBxQMplPLfYp%2BoLCKV5rv%2FzR7RvqPk6v5TxhARrSZj5yqXcC6mZ2OhlK1UDSaWysLENT8BNwWa1rJiA7VOwicCo9YVeBl%2BkkuyzKlITCvthRfdTRoF1QIV2Zmxp%2F1qqpRVhOWdhXxXlRPes9h4FvbQfWXShdma3VHfHIAciXSCNZCC6OBu7VlZesIWF8b7wo%2Fa3BU7el6skfal3qlR%2BVNrjBtkS0aSCyQFsXNpJshwmC3J1X%2FxnsNiA67igLSSIMvy41rN%2Fe%2B1NK4reWHQzmHG0siqZKOVOcsgiFDr0STS4byuGkVd95mlndyVR3rZoiZj8wFMI2X%2BLqd6iQ2OvGKrH7FwLkS%2Fa3E%2BYsuhkduQCH91y385AMiLwfUdOSc%2Fpu8mGT2U4mnaNwwpd68lwrD3&__VIEWSTATEGENERATOR=E08963AD&__VIEWSTATEENCRYPTED=&__EVENTVALIDATION=Ceyz650IL4OhDS0syr0KXWxq4V7p5ovghORzJ7hpYr3IdszhfCwfS9AJnnGwMbNOp5fGgCRX5uTUqrXVsVCHe7gb9NfLIsY8ZIOo3z894NI0%2Fr4C&StudentNo=20131002&StudentName=&Button1=%B2%E9%D1%AF&SearchStyleControl_currentState=False


我的post实现主体贴在下面

[C#] 纯文本查看 复制代码

public string HttpPost(string Url,string strPostdata)
        {
            StringBuilder content = new StringBuilder();
            try
            {
                // 与指定URL创建HTTP请求
                HttpWebRequest request = (HttpWebRequest)WebRequest.Create(Url);
                request.UserAgent = "Mozilla/5.0 (Windows NT 6.3; WOW64; Trident/7.0; rv:11.0) like Gecko";
                request.Method = "POST";
                request.Accept = "*/*";
//出于隐私考虑，cookie实际内容“键”、“值”代替
                CookieContainer objcok = new CookieContainer();
                objcok.Add(new Uri("http://www.yanghua.net/SystemForm/Student/Search/StuInfoSearch.aspx"), new Cookie("键", "值"));
                objcok.Add(new Uri("http://www.yanghua.net/SystemForm/Student/Search/StuInfoSearch.aspx"), new Cookie("键", "值"));
                objcok.Add(new Uri("http://www.yanghua.net/SystemForm/Student/Search/StuInfoSearch.aspx"), new Cookie("键", "值"));
                request.CookieContainer = objcok;

                //不保持连接
                request.KeepAlive = true;
                byte[] buffer = Encoding.Default.GetBytes(strPostdata);
                request.ContentLength = buffer.Length;

                request.GetRequestStream().Write(buffer, 0, buffer.Length);
             

                // 获取对应HTTP请求的响应
                HttpWebResponse response = (HttpWebResponse)request.GetResponse();

                // 获取响应流
                Stream responseStream = response.GetResponseStream();

                // 对接响应流(以"GBK"字符集)
                StreamReader sReader = new StreamReader(responseStream, Encoding.GetEncoding("gb2312"));

                // 开始读取数据
                Char[] sReaderBuffer = new Char[256];
                int count = sReader.Read(sReaderBuffer, 0, 256);
                while (count > 0)
                {
                    String tempStr = new String(sReaderBuffer, 0, count);
                    content.Append(tempStr);
                    count = sReader.Read(sReaderBuffer, 0, 256);
                }
                // 读取结束
                sReader.Close();
            }
            catch (Exception)
            {
                content = new StringBuilder("Runtime Error");
            }

            return content.ToString();
        }

但是我把上述请求正文作为postdata传入的时候，得到的响应却不是预期的响应。
预期响应片段：


实际响应片段：

不知道为什么会未找到相关数据。
不知道我有没有把我的问题描述清楚了。如果还需要其他信息，我再提供。希望大神们能给一个解决方案，已经卡了两天了。谨拜谢！

站长苏飞

StudentNo=20131002&StudentName=&Button1=%B2%E9%D1%AF&SearchStyleControl_currentState=False 参数应该是只要这一部分就行了，

你再看看是不是Cookiei不对

CrazyTdkgn

站长苏飞 发表于 2014-10-16 13:13
StudentNo=20131002&StudentName=&Button1=%B2%E9%D1%AF&SearchStyleControl_currentState=False 参数应该 ...

站长，我刚刚在你的苏飞开发助手里面已经调试出正确响应了，问题不在cookie和Post数据，我在高级选项里面的ContentType里面选“application/x-www-form-urlencoded”（默认是text/html）就能得到正确响应。
我在代码里面加上

[C#] 纯文本查看 复制代码

response.ContentType = "application/x-www-form-urlencoded";

但是post返回了“Runtime Error”。我想知道在方法里面怎么改才能同样得到正确响应？