很多时候我们要用HttpWebRequest组件模拟http协议发送web请求，封装一个请求类看起来就很有必要了。要很好的封装一个这样的类，要考虑很多因素，比如通用性和异常处理，甚至还可以是继承性。当然，我下面要说的是一个静态类，继承什么的就算了，简单封装一下能用就行，呵呵，太懒了。
1 using System;
2 using System.Collections.Generic;
3 using System.Text;
4 using System.Net;
5 using System.IO;
6
7 namespace Uu102
8 {
9 /// <summary>
10 ///http协议模拟请求类
11 ///主要考虑请求后的具体结果
12 ///此类出自 uu102.com，请尊重原作者，转载请加上此链接
13 /// </summary>
14 class HttpHelper
15 {
16 /// <summary>
17 /// 请求并发限制数目
18 /// </summary>
19 private static int DefaultConnectionLimit=1;
20 private const string Accept = "*/*";
21 private const string UserAgent = "Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; .NET CLR 2.0.50727; .NET CLR 3.0.04506.648; .NET CLR 3.5.21022)";
22 private const string ContentType = "application/x-www-form-urlencoded";
23
24 /// <summary>
25 /// 发送资源请求。返回请求到的响应文本
26 /// 之所以看到这么多形参，只是本人的水平很菜的体现^.^
27 /// 注意，这个类并没有处理https加密请求
28 /// </summary>
29 /// <param name="url">发送请求的url地址</param>
30 /// <param name="postString"></param>
31 /// <param name="IsPost"></param>
32 /// <param name="cookieContainer"></param>
33 /// <param name="referer"></param>
34 /// <param name="encoding"></param>
35 /// <returns></returns>
36 public static string GetHtml(string url, string postString, bool IsPost, CookieContainer cookieContainer, string referer, Encoding encoding)
37 {
38 string html = string.Empty;
39 ServicePointManager.Expect100Continue = false;
40 ServicePointManager.DefaultConnectionLimit = DefaultConnectionLimit;//设置并发连接数限制上额
41 DefaultConnectionLimit++;
42 if (string.IsNullOrEmpty(postString)) IsPost = false;
43 HttpWebRequest httpWebRequest = null;
44
45 HttpWebResponse httpWebResponse = null;
46 try
47 {
48 httpWebRequest = (HttpWebRequest)HttpWebRequest.Create(url);//创建连接请求
49 httpWebRequest.Method = IsPost ? "POST" : "GET";
50 if (cookieContainer != null) httpWebRequest.CookieContainer = cookieContainer;
51 httpWebRequest.AllowAutoRedirect = true;//【注意】这里有个时候在特殊情况下要设置为否，否则会造成cookie丢失
52 httpWebRequest.ContentType = ContentType;
53 httpWebRequest.Accept = Accept;
54 httpWebRequest.UserAgent = UserAgent;
55 if (!string.IsNullOrEmpty(referer)) httpWebRequest.Referer = referer;
56 if (IsPost) //如果是Post递交数据，则写入传的字符串数据
57 {
58 byte[] byteRequest = Encoding.Default.GetBytes(postString);
59 httpWebRequest.ContentLength = byteRequest.Length;
60 Stream stream = httpWebRequest.GetRequestStream();
61 stream.Write(byteRequest, 0, byteRequest.Length);
62 stream.Close();
63 }
64
65 httpWebResponse = (HttpWebResponse)httpWebRequest.GetResponse();//开始获取响应流
66 Stream responseStream = httpWebResponse.GetResponseStream();
67 StreamReader streamReader = new StreamReader(responseStream, encoding);
68 html = streamReader.ReadToEnd();//注意这里是直接将所有的字节从头读到尾，也可以一行一行的控制，节省时间
69 streamReader.Close();
70 responseStream.Close();
71 httpWebRequest.Abort();
72
73 foreach (Cookie cookie in httpWebResponse.Cookies) //获取cookie
74 {
75 cookieContainer.Add(cookie);
76 }
77
78 httpWebResponse.Close();
79 //到这里为止，所有的对象都要释放掉，以免内存像滚雪球一样
80 return html;
81 }
82 catch
83 {
84 DefaultConnectionLimit--;
85 //我这里就没做任何处理了，这里最好还是处理一下
86 return null;
87 }
88
89 }
90 #region 重载方法
91 public static string GetHtml(string url, string postString, CookieContainer cookieContainer, string referer)
92 {
93 return GetHtml(url, postString, true, cookieContainer, referer, Encoding.UTF8);
94 }
95 public static string GetHtml(string url, string postString, CookieContainer cookieContainer)
96 {
97 return GetHtml(url, postString, true, cookieContainer, url, Encoding.UTF8);
98 }
99 public static string GetHtml(string url, CookieContainer cookieContainer, string referer)
100 {
101 return GetHtml(url, "", false, cookieContainer, referer, Encoding.UTF8);
102 }
103 public static string GetHtml(string url, CookieContainer cookieContainer)
104 {
105 return GetHtml(url, "", false, cookieContainer, url, Encoding.UTF8);
106 }
107 public static string GetHtml(string url)
108 {
109 return GetHtml(url, "", true, null, url, Encoding.UTF8);
110 }
111 #endregion
112 /// <summary>
113 /// 这个方法主要用来获取非文本的html响应正文
114 /// </summary>
115 /// <param name="url"></param>
116 /// <param name="cookieContainer"></param>
117 /// <returns></returns>
118 public static Stream GetStream(string url,CookieContainer cookieContainer)
119 {
120 HttpWebRequest httpWebRequest = null;
121 HttpWebResponse httpWebResponse = null;
122
123 try
124 {
125
126 httpWebRequest = (HttpWebRequest)HttpWebRequest.Create(url);
127 httpWebRequest.CookieContainer = cookieContainer;
128 httpWebResponse = (HttpWebResponse)httpWebRequest.GetResponse();
129 Stream responseStream = httpWebResponse.GetResponseStream();
130 return responseStream;
131 }
132 catch
133 {
134 if (httpWebRequest != null)
135 {
136 httpWebRequest.Abort();
137 } if (httpWebResponse != null)
138 {
139 httpWebResponse.Close();
140 }
141 return null;
142 }
143 }
144
145 }
146 }
代码太简单解释都免了吧？要强调的一点，上面的封装类还没有处理https这样的加密连接，以及返回的status和异常，如果是自己调试，最好是将try这个功能注释掉，免得看了半天都不知道哪出了问题。
以上的功能虽然能适合绝大部分请求，但是仍有一些请客不适合，比如当模拟上传文件等等的情况就不适用。
