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.NET中HttpWebRequest模拟请求保持登录状态

　　最近碰到这样一个需求，ASP项目里需要从另一个API项目的接口中取数据。

　　我想了想，最方便也是最快速的方法的就是使用HttpWebRequest请求接口。

　　而这里有一个问题，就是API那边接口需要登录之后才能拿到完整的数据。

　未登录价格显示不全:

　　由于之前未曾使用过HttpWebRequest，所以并不知道登录完成之后要怎样保持登录状态，进行接下来的请求；

　　花费了我两天时间才研究明白（本人菜鸡，大神轻喷），HttpWebRequest每次请求，服务端是不同的Session, 对于需要登录保持Session才能操作的页面，无法进行。这就要求程序每次请求在同一个Session中。

　　服务端每次识别客户端在同一个Session访问，是基于cookie中有SessionID值。每次访问服务端时，服务端通过识别客户请求的cookie的SessionID值，来判断是否在同一个Session中。那么就需要在拿列表数据之前，先请求一次登陆接口，然后拿到这次请求的Cookie。

　　HttpWebRequest帮助类：

  1  public class HttpRequest
  2     {
  3         // 保持 Cookie 为同一 Cookie 值。         
  4         protected CookieContainer craboCookie = new CookieContainer();
  5         protected string _Uri = null;         // 标识 Internet 资源的 URI 
  6         protected string _Referer = null;         // 标识 Internet 资源请求的 Referer        
  7         protected string _Headers = null;         // 标识 Internet 资源请求的 Header 
  8         // 标识 Internet 资源请求的 Accept 
  9         protected string _Accept = "image/gif, image/x-xbitmap, image/jpeg, image/pjpeg, application/x-shockwave-flash, application/vnd.ms-excel, application/vnd.ms-powerpoint, application/msword, */*";
 10         protected List<string> cookiesstrs = null;
 11         protected string cookiesstr = null;
 12         protected CookieCollection cookieheader = null;
 13 
 14         protected string _Method = null;         // 标识 Internet 资源请求的 Method 
 15         protected string _Data = null;         // POST 请求时的数据 
 16         protected string _CharacterSet = null;         // 响应的字符集 
 17         protected HttpStatusCode _StatusCode;         // 响应状态 
 18         protected StringBuilder _Html_Text = new StringBuilder();
 19         public bool IsException = false;
 20         public int TimeOut = 20000;
 21         public HttpRequest(String encode = "GB2312")
 22         {
 23             // 
 24             // TODO: 在此处添加构造函数逻辑 
 25             // 
 26             cookiesstrs = new List<string>();
 27            _CharacterSet = encode;
 28         }
 29         /// <summary> 
 30         /// 对 Internet 资源发起 GET 请求 
 31         /// </summary> 
 32         /// <param name="requestUriString">标识 Internet 资源的URI</param> 
 33         /// <param name="requestReferer">标识 Internet 资源请求的Referer</param> 
 34         public bool OpenRequest(string requestUriString, string requestReferer)
 35         {
 36             _Uri = requestUriString;
 37             _Referer = requestReferer;
 38             _Method = "GET";
 39             return OpenRequest();
 40         }
 41         /// <summary> 
 42         /// 对 Internet 资源发起 GET 请求 
 43         /// </summary> 
 44         /// <param name="requestUriString">标识 Internet资源的URI</param> 
 45         /// <param name="requestReferer">标识 Internet资源请求的Referer</param> 
 46         /// <param name="requestMethod">标识 Internet资源请求的 Post 数据</param> 
 47         public bool OpenRequest(string requestUriString, string requestReferer, string requestData)
 48         {
 49             _Uri = requestUriString;
 50             _Referer = requestReferer;
 51             _Data = requestData;
 52             _Method = "POST";
 53             return OpenRequest();
 54         }
 55         public bool OpenRequestNew(string requestUriString, string requestReferer, string requestData)
 56         {
 57             _Uri = requestUriString;
 58             _Referer = requestReferer;
 59             _Data = requestData;
 60             _Method = "POST";
 61             return OpenRequestNew();
 62         }
 63         public void SetCookieheader(string Cookie)
 64         {
 65 
 66             cookiesstrs.Add(Cookie);
 67              
 68         }
 69       
 70         /// <summary> 
 71         public string GetCookieheader()
 72         {
 73             return cookiesstr;  
 74         }
 75 
 76         public void SetCookie(CookieCollection Cookie)
 77         { 
 78             craboCookie.Add(Cookie);
 79         }
 80         public CookieCollection GetCookie()
 81         {
 82             return cookieheader;
 83         }
 84 
 85         /// 对 Internet 资源发起请求 
 86         /// </summary> 
 87         /// <returns></returns> 
 88         private bool OpenRequest()
 89         {
 90             // 清空已保留代码 
 91             _Html_Text.Remove(0, _Html_Text.Length);
 92             // 创建 HttpWebRequest 实例 
 93             HttpWebRequest Request = (HttpWebRequest)WebRequest.Create(_Uri);
 94             // 设置跟随重定向 
 95             Request.AllowAutoRedirect = true;
 96             #region 判断 Uri 资源类型
 97             {
 98                 Regex _RegexUri = new Regex("^https://", RegexOptions.IgnoreCase);
 99                 if (_RegexUri.IsMatch(_Uri))
100                     ServicePointManager.CertificatePolicy = new TrustAllCertificatePolicy();
101             };
102             #endregion
103 
104             //System.Net.WebProxy proxy = new System.Net.WebProxy("172.168.2.254:8080", true);
105             //proxy.Credentials = new NetworkCredential("linxy", "lxy123456");
106             //Request.Proxy = proxy;
107          
108             Request.Timeout = TimeOut;
109             Request.Method = _Method;
110             Request.Accept = _Accept;
111             Request.UserAgent = "Mozilla/5.0 (X11; U; Linux i686; zh-CN; rv:1.9.1.2) Gecko/20090803 Fedora/3.5.2-2.fc11 Firefox/3.5.2";
112             Request.Referer = _Referer;
113             Request.Proxy = null;
114             Request.CookieContainer = craboCookie;
115 
119             if (_Method == "POST")
120             {
121                 #region 请求为 POST
122                 Request.ContentType = "application/x-www-form-urlencoded";
123               
124                 byte[] Bytes = Encoding.GetEncoding(_CharacterSet).GetBytes(_Data);
125                 Request.ContentLength = Bytes.Length;
126                 using (Stream writer = Request.GetRequestStream())
127                 {
128                     writer.Write(Bytes, 0, Bytes.Length);
129                     writer.Close();
130                 }
131                 #endregion
132             }
133             #region 读取返回数据
134             // 设置返回值变量 
135             bool bResult = true;
136             try
137             {
138                 HttpWebResponse Response = (HttpWebResponse)Request.GetResponse();
139                 cookiesstr = Response.Headers["Set-Cookie"]?.ToString();
140                 cookieheader = Request.CookieContainer.GetCookies(new Uri(_Uri));
141                 // 获取状态值 
142                 _StatusCode = Response.StatusCode;
143                 if (_StatusCode == HttpStatusCode.OK)
144                 {
145                     
146                      // 判断页面编码 
147                     string ContentEncoding = Response.ContentEncoding.ToLower();
148                     switch (ContentEncoding)
149                     {
150                         case "gzip":
151                            
152                             break;
153                         default:
154                             using (Stream reader = Response.GetResponseStream())
155                             {
156                                 StreamReader sr = new StreamReader(reader, Encoding.GetEncoding(CharacterSet));
157                                 _Html_Text.Append(sr.ReadToEnd());
158                                 sr.Close();
159                                 reader.Close();
160                                 try
161                                 {
162                                 _doc.RemoveAll();
163                                     _doc.LoadXml(_Html_Text.ToString().Trim());
164                             }
165                                 catch{}
166                             }
167                             break;
168                     }
169                  }
170                 else
171                     bResult = false;
172             }
173             catch (Exception pEx)
174             {
175                 IsException = true;
176                 _Html_Text.Append(pEx.Message);
177                 return false;
178             }
179             #endregion
180             return bResult;
181         }
182         private bool OpenRequestNew()
183         {
184             // 清空已保留代码 
185             _Html_Text.Remove(0, _Html_Text.Length);
186             // 创建 HttpWebRequest 实例 
187             HttpWebRequest Request = (HttpWebRequest)WebRequest.Create(_Uri);
188             // 设置跟随重定向 
189             Request.AllowAutoRedirect = true;
190             #region 判断 Uri 资源类型
191             {
192                 Regex _RegexUri = new Regex("^https://", RegexOptions.IgnoreCase);
193                 if (_RegexUri.IsMatch(_Uri))
194                     ServicePointManager.CertificatePolicy = new TrustAllCertificatePolicy();
195             };
196             #endregion
197 
198             //System.Net.WebProxy proxy = new System.Net.WebProxy("172.168.2.254:8080", true);
199             //proxy.Credentials = new NetworkCredential("linxy", "lxy123456");
200             //Request.Proxy = proxy;
201 
202             Request.Timeout = TimeOut;
203             Request.Method = _Method;
204             Request.Accept = _Accept;
205             Request.UserAgent = "Mozilla/5.0 (X11; U; Linux i686; zh-CN; rv:1.9.1.2) Gecko/20090803 Fedora/3.5.2-2.fc11 Firefox/3.5.2";
206             Request.Referer = _Referer;
207             Request.Proxy = null;
208  
209             foreach (var cookie in cookiesstrs)
210             {
211                 Request.Headers.Add("Cookie", cookie);
212             }
213            
214             if (_Method == "POST")
215             {
216                 #region 请求为 POST
217                 Request.ContentType = "application/x-www-form-urlencoded";
218 
219                 byte[] Bytes = Encoding.GetEncoding(_CharacterSet).GetBytes(_Data);
220                 Request.ContentLength = Bytes.Length;
221                 using (Stream writer = Request.GetRequestStream())
222                 {
223                     writer.Write(Bytes, 0, Bytes.Length);
224                     writer.Close();
225                 }
226                 #endregion
227             }
228             #region 读取返回数据
229             // 设置返回值变量 
230             bool bResult = true;
231             try
232             {
233                 HttpWebResponse Response = (HttpWebResponse)Request.GetResponse();
234 
235                 // 获取状态值 
236                 _StatusCode = Response.StatusCode;
237                 if (_StatusCode == HttpStatusCode.OK)
238                 {
239 
240                     // 判断页面编码 
241                     string ContentEncoding = Response.ContentEncoding.ToLower();
242                     switch (ContentEncoding)
243                     {
244                         case "gzip":
245 
246                             break;
247                         default:
248                             using (Stream reader = Response.GetResponseStream())
249                             {
250                                 StreamReader sr = new StreamReader(reader, Encoding.GetEncoding(CharacterSet));
251                                 _Html_Text.Append(sr.ReadToEnd());
252                                 sr.Close();
253                                 reader.Close();
254                                 try
255                                 {
256                                     _doc.RemoveAll();
257                                     _doc.LoadXml(_Html_Text.ToString().Trim());
258                                 }
259                                 catch { }
260                             }
261                             break;
262                     }
263                     cookiesstr = craboCookie.GetCookieHeader(Request.RequestUri); //把cookies转换成字符串
264                 }
265                 else
266                     bResult = false;
267             }
268             catch (Exception pEx)
269             {
270                 IsException = true;
271                 _Html_Text.Append(pEx.Message);
272                 return false;
273             }
274             #endregion
275             return bResult;
276         }
277         private XmlDocument _doc = new XmlDocument();
278 
279         public XmlDocument Doc
280         {
281             get
282             {
283                 return _doc;
284             }
285         }
286         
287 
288         /// <summary> 
289         /// 获取或设置 Uri 资源字符集 
290         /// </summary> 
291         public string CharacterSet
292         {
293             get
294             {
295                 return _CharacterSet;
296             }
297             set
298             {
299                 _CharacterSet = value;
300             }
301         }
302         /// <summary> 
303         /// 获取或设置 Uri 资源标识 
304         /// </summary> 
305         public string RequestUriString
306         {
307             get
308             {
309                 return _Uri;
310             }
311             set
312             {
313                 _Uri = value;
314             }
315         }
316         /// <summary> 
317         /// 获取或设置 Uri 资源请求 Accept 
318         /// </summary> 
319         public string Accept
320         {
321             get
322             {
323                 return _Accept;
324             }
325             set
326             {
327                 _Accept = value;
328             }
329         }
330         public string HtmlDocument
331         {
332             get
333             {
334                 return _Html_Text.ToString();
335             }
336         }
337 
338         
339     }

　　HttpWebrequest设置cookie可以用以下两种方式：

Request.CookieContainer = craboCookie;
Request.Headers.Add("Cookie", cookie);

　　调用方法：

  HttpRequest hr = new  HttpRequest("UTF-8");
  string strUrl = APIUrl + "/IAccount/Login";
  string strUrlPan = string.Format("customerID={0}&md5Pwd={1}&loginType={2}&source={3}", txtUid.Text.Trim(), Util.GetMD5(txtPwd.Text.Trim()), 1, 3);
  hr.OpenRequest(strUrl + "?" + strUrlPan, "");
  //缓存登录Cookie
  Session["Cookieheader"] = hr.GetCookie(); 
  var rb = Newtonsoft.Json.JsonConvert.DeserializeObject<LoginResponseData>(hr.HtmlDocument.Trim());
  //保存站点
  CookieUtil.ClearCookie("ChangeWebSiteSysNo");
  CookieUtil.SetCookie("ChangeWebSiteSysNo", rb.data.CustomerInfo.WebSiteSysNo.ToString());
  //保存登录用户标识
  string cookiestr = hr.GetCookieheader();
  string str = getCookie(cookiestr, "path=/,userGuid").Replace("path=/,", "");
  var cookieArr = str.Split('=');
  CookieUtil.ClearCookie("userGuid");
  CookieUtil.SetCookie("userGuid", cookieArr.Length > 0 ? cookieArr[1] : "");

这里有一个比较坑的就是，因为我那边API项目不仅要验证是否登录还要验证用户唯一标识，所以我这里将userGuid也缓存了起来在下一次请求时一并传过去。

然后再另起一个请求拿数据

//设置请求登录Cookie
Icson.Utils.HttpRequest hr1 = new Icson.Utils.HttpRequest("UTF-8");
System.Net.CookieCollection Cookies = new System.Net.CookieCollection();
if (Session["Cookieheader"] != null)
　　Cookies.Add((System.Net.CookieCollection)Session["Cookieheader"]);
Cookies.Add(new System.Net.Cookie("userGuid", CookieUtil.GetCookie("userGuid"), "/", APIUrl.Replace("http://", "")));
hr1.SetCookie(Cookies);
//请求商品列表
string strUrl = APIUrl + "/IProductList/ListNew";
string strUrlPan = string.Format("c1SysNo={0}&c2SysNo={1}&c3SysNo={2}&extCode={3}&filter={4}&limit=30&madeIn=-1&offset={5}&query={6}&sType=1&sort=8&source=3&systemversion=9&version=3.2.2", ddlC1.SelectedItem?.Value.TryInt() < 0 ? "" : ddlC1.SelectedItem?.Value, ddlC2.SelectedItem?.Value.TryInt() < 0 ? "" : ddlC2.SelectedItem?.Value, "", 0, "", 0, txtProductName.Text.Trim());
hr1.OpenRequest(strUrl + "?" + strUrlPan, "", "");

这样就可以拿到完整的列表数据了

以上就是一次HttpWebRequest踩坑经历，希望各位遇到能够避免在这上面浪费过多时间。

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原文地址：https://www.cnblogs.com/AlexZha/p/13691557.html