HttpWebRequest類與HttpRequest類的區別。

HttpRequest類的對象用于服務器端，獲取客戶端傳來的請求的信息，包括HTTP報文傳送過來的所有信息。而HttpWebRequest用于客戶端，拼接請求的HTTP報文并發送等。

HttpWebRequest這個類非常強大，強大的地方在于它封裝了幾乎HTTP請求報文里需要用到的東西，以致于能夠能夠發送任意的HTTP請求并獲得服務器響應(Response)信息。采集信息常用到這個類。在學習這個類之前，首先有必要了解下HTTP方面的知識。

一、簡單示例

我們先來一個最簡單的，就是緊緊輸入一個網址就獲取響應。代碼如下：

class Program{static void Main(string[] args){HttpWebRequest request = (HttpWebRequest)HttpWebRequest.Create("http://www.baidu.com"); //創建一個請求示例HttpWebResponse response = (HttpWebResponse)request.GetResponse();　　//獲取響應，即發送請求Stream responseStream = response.GetResponseStream();StreamReader streamReader = new StreamReader(responseStream, Encoding.UTF8);string html = streamReader.ReadToEnd();Console.WriteLine(html);Console.ReadKey();}}

OK，就是這么簡單了，真的這么簡單嗎？發送一個HTTP請求真的這么簡單。但是要做出很多功能就不簡單了。你需要詳細了解下HTTP方面的知識，比如HTTP請求報文之類的。

二、模擬登錄

下面來個復雜點的，這次是獲取登錄之后的頁面。登錄之后的請求用什么實現呢？呵呵，用到是cookie。在拼接HTTP請求的時候，連著cookie也發送過去。

namespace ConsoleApplication1 {class Program{static void Main(string[] args){HttpHeader header = new HttpHeader();header.accept = "image/gif, image/x-xbitmap, image/jpeg, image/pjpeg, application/x-shockwave-flash, application/x-silverlight, application/vnd.ms-excel, application/vnd.ms-powerpoint, application/msword, application/x-ms-application, application/x-ms-xbap, application/vnd.ms-xpsdocument, application/xaml+xml, application/x-silverlight-2-b1, */*";header.contentType = "application/x-www-form-urlencoded";header.method = "POST";header.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)";header.maxTry = 300;//在這里自己拼接一下Cookie，不用復制過來的那個GetCookie方法了，原來的那個寫法還是比較嚴謹的CookieContainer cc = new CookieContainer();Cookie cUserName = new Cookie("cSpaceUserEmail", "742783833%40qq.com");cUserName.Domain = ".7soyo.com";Cookie cUserPassword = new Cookie("cSpaceUserPassWord", "4f270b36a4d3e5ee70b65b1778e8f793");cUserPassword.Domain = ".7soyo.com";cc.Add(cUserName);cc.Add(cUserPassword);string html = HTMLHelper.GetHtml("http://user.7soyo.com/CollectUser/List", cc, header);FileStream fs = new FileStream(@"D:\123.txt",FileMode.CreateNew,FileAccess.ReadWrite);fs.Write(Encoding.UTF8.GetBytes(html),0,html.Length);fs.Flush();fs.Dispose();Console.WriteLine(html);Console.ReadKey();}}public class HTMLHelper{/// <summary>/// 獲取CooKie/// </summary>/// <param name="loginUrl"></param>/// <param name="postdata"></param>/// <param name="header"></param>/// <returns></returns>public static CookieContainer GetCooKie(string loginUrl, string postdata, HttpHeader header){HttpWebRequest request = null;HttpWebResponse response = null;try{CookieContainer cc = new CookieContainer();request = (HttpWebRequest)WebRequest.Create(loginUrl);request.Method = header.method;request.ContentType = header.contentType;byte[] postdatabyte = Encoding.UTF8.GetBytes(postdata); //提交的請求主體的內容request.ContentLength = postdatabyte.Length; //提交的請求主體的長度request.AllowAutoRedirect = false;request.CookieContainer = cc;request.KeepAlive = true;//提交請求 Stream stream;stream = request.GetRequestStream();stream.Write(postdatabyte, 0, postdatabyte.Length); //帶上請求主體 stream.Close();//接收響應response = (HttpWebResponse)request.GetResponse(); //正式發起請求response.Cookies = request.CookieContainer.GetCookies(request.RequestUri);CookieCollection cook = response.Cookies;//Cookie字符串格式string strcrook = request.CookieContainer.GetCookieHeader(request.RequestUri);return cc;}catch (Exception ex){throw ex;}}/// <summary>/// 獲取html/// </summary>/// <param name="getUrl"></param>/// <param name="cookieContainer"></param>/// <param name="header"></param>/// <returns></returns>public static string GetHtml(string getUrl, CookieContainer cookieContainer, HttpHeader header){Thread.Sleep(1000);HttpWebRequest httpWebRequest = null;HttpWebResponse httpWebResponse = null;try{httpWebRequest = (HttpWebRequest)HttpWebRequest.Create(getUrl);httpWebRequest.CookieContainer = cookieContainer;httpWebRequest.ContentType = header.contentType;httpWebRequest.ServicePoint.ConnectionLimit = header.maxTry;httpWebRequest.Referer = getUrl;httpWebRequest.Accept = header.accept;httpWebRequest.UserAgent = header.userAgent;httpWebRequest.Method = "GET";httpWebResponse = (HttpWebResponse)httpWebRequest.GetResponse();Stream responseStream = httpWebResponse.GetResponseStream();StreamReader streamReader = new StreamReader(responseStream, Encoding.UTF8);string html = streamReader.ReadToEnd();streamReader.Close();responseStream.Close();httpWebRequest.Abort();httpWebResponse.Close();return html;}catch (Exception e){if (httpWebRequest != null) httpWebRequest.Abort();if (httpWebResponse != null) httpWebResponse.Close();return string.Empty;}}}public class HttpHeader{public string contentType { get; set; }public string accept { get; set; }public string userAgent { get; set; }public string method { get; set; }public int maxTry { get; set; }} }

這樣獲取到的就是登錄之后的頁面了。

三、模擬表單提交

再來一個例子，運用HttpWebRequest來模擬表單的提交，先新建一個MVC項目，里面只有這些代碼：

[HttpPost] public ActionResult Index(string userName,string userPassword) {string str = "你提交過來的用戶名是:" + userName + ",密碼是: " + userPassword;Response.Write(str);return View(); }

然后啟動該項目，再新建另外一個項目,用于模擬提交表單，然后注意路徑填寫的是剛才建的那個MVC項目。

static void Main(string[] args){HttpWebRequest request = null;HttpWebResponse response = null;CookieContainer cc = new CookieContainer();request = (HttpWebRequest)WebRequest.Create("http://localhost:2539/");request.Method = "POST";request.ContentType = "application/x-www-form-urlencoded";request.UserAgent = "Mozilla/5.0 (Windows NT 6.1; rv:19.0) Gecko/20100101 Firefox/19.0";string requestForm = "userName=1693372175&userPassword=123456"; //拼接Form表單里的信息byte[] postdatabyte = Encoding.UTF8.GetBytes(requestForm);request.ContentLength = postdatabyte.Length;request.AllowAutoRedirect = false;request.CookieContainer = cc;request.KeepAlive = true;Stream stream;stream = request.GetRequestStream();stream.Write(postdatabyte, 0, postdatabyte.Length); //設置請求主體的內容 stream.Close();//接收響應response = (HttpWebResponse)request.GetResponse();Console.WriteLine();Stream stream1 = response.GetResponseStream();StreamReader sr = new StreamReader(stream1);Console.WriteLine(sr.ReadToEnd());Console.ReadKey();}

輸出結果如下所示：

四、模擬上傳

血的教訓，注意路徑不能寫錯，否則在對流進行操作時，Write，就會報錯：

?HttpWebRequest request = (HttpWebRequest)WebRequest.Create("http://localhost:9170/upload/test");?

客戶端：

class Program{/** * 如果要在客戶端向服務器上傳文件，我們就必須模擬一個POST multipart/form-data類型的請求 * Content-Type必須是multipart/form-data。 * 以multipart/form-data編碼的POST請求格式與application/x-www-form-urlencoded完全不同 * multipart/form-data需要首先在HTTP請求頭設置一個分隔符,例如7d4a6d158c9： * 我們模擬的提交要設定 content-type不同于非含附件的post時候的content-type * 這里需要： ("Content-Type", "multipart/form-data; boundary=ABCD"); * 然后，將每個字段用“--7d4a6d158c9”分隔，最后一個“--7d4a6d158c9--”表示結束。 * 例如，要上傳一個title字段"Today"和一個文件C:\1.txt，HTTP正文如下： * * --7d4a6d158c9 * Content-Disposition: form-data; name="title" * \r\n\r\n * Today * --7d4a6d158c9 * Content-Disposition: form-data; name="1.txt"; filename="C:\1.txt" * Content-Type: text/plain * 如果是圖片Content-Type: application/octet-stream * \r\n\r\n * <這里是1.txt文件的內容> * --7d4a6d158c9 * \r\n * 請注意，每一行都必須以\r\n結束value前面必須有2個\r\n，包括最后一行。 */static void Main(string[] args){string boundary = "----------" + DateTime.Now.Ticks.ToString("x");//元素分割標記 StringBuilder sb = new StringBuilder();sb.Append("--" + boundary);sb.Append("\r\n");sb.Append("Content-Disposition: form-data; name=\"file1\"; filename=\"D:\\upload.xml" + "\"");sb.Append("\r\n");sb.Append("Content-Type: application/octet-stream");sb.Append("\r\n");sb.Append("\r\n");//value前面必須有2個換行 HttpWebRequest request = (HttpWebRequest)WebRequest.Create("http://localhost:9170/upload/test");request.ContentType = "multipart/form-data; boundary=" + boundary;//其他地方的boundary要比這里多-- request.Method = "POST";FileStream fileStream = new FileStream(@"D:\123.xml", FileMode.OpenOrCreate, FileAccess.Read);byte[] postHeaderBytes = Encoding.UTF8.GetBytes(sb.ToString());byte[] boundaryBytes = Encoding.ASCII.GetBytes("\r\n--" + boundary + "\r\n");//http請求總長度 request.ContentLength = postHeaderBytes.Length + fileStream.Length + boundaryBytes.Length;Stream requestStream = request.GetRequestStream(); requestStream.Write(postHeaderBytes, 0, postHeaderBytes.Length);byte[] buffer = new Byte[checked((uint)Math.Min(4096, (int)fileStream.Length))];int bytesRead = 0;while ((bytesRead = fileStream.Read(buffer, 0, buffer.Length)) != 0){requestStream.Write(buffer, 0, bytesRead);}fileStream.Dispose();requestStream.Write(boundaryBytes, 0, boundaryBytes.Length);WebResponse webResponse2 = request.GetResponse();Stream htmlStream = webResponse2.GetResponseStream();string HTML = GetHtml(htmlStream, "UTF-8");Console.WriteLine(HTML);htmlStream.Dispose();}}

測試服務器端地址：

public ActionResult Test(){HttpRequest request = System.Web.HttpContext.Current.Request;HttpFileCollection FileCollect = request.Files;if (FileCollect.Count > 0) //如果集合的數量大于0 {foreach (string str in FileCollect){HttpPostedFile FileSave = FileCollect[str]; //用key獲取單個文件對象HttpPostedFilestring imgName = DateTime.Now.ToString("yyyyMMddhhmmss");string AbsolutePath = FileSave.FileName;FileSave.SaveAs(AbsolutePath); //將上傳的東西保存 }}return Content("鍵值對數目：" + FileCollect.Count);}

?

轉載于:https://www.cnblogs.com/a-dou/p/5755229.html

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