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HttpWebRequest类
HttpWebRequest类与HttpRequest类的区别。
HttpRequest类的对象用于服务器端，获取客户端传来的请求的信息，包括HTTP报文传送过来的所有信息。而HttpWebRequest用于客户端，拼接请求的HTTP报文并发送等。
HttpWebRequest这个类非常强大，强大的地方在于它封装了几乎HTTP请求报文里需要用到的东西，以致于能够能够发送任意的HTTP请求并获得服务器响应(Response)信息。采集信息常用到这个类。在学习这个类之前，首先有必要了解下HTTP方面的知识。
一、简单示例
我们先来一个最简单的，就是紧紧输入一个网址就获取响应。代码如下：
class Program { static void Main(string[] args) { HttpWebRequest request = (HttpWebRequest)HttpWebRequest.Create("http://www.baidu.com"); //创建一个请求示例 HttpWebResponse response = (HttpWebResponse)request.GetResponse(); //获取响应，即发送请求 Stream responseStream = response.GetResponseStream(); StreamReader streamReader = new StreamReader(responseStream, Encoding.UTF8); string html = streamReader.ReadToEnd(); Console.WriteLine(html); Console.ReadKey(); } }OK，就是这么简单了，真的这么简单吗？发送一个HTTP请求真的这么简单。但是要做出很多功能就不简单了。你需要详细了解下HTTP方面的知识，比如HTTP请求报文之类的。
二、模拟登录
下面来个复杂点的，这次是获取登录之后的页面。登录之后的请求用什么实现呢？呵呵，用到是cookie。在拼接HTTP请求的时候，连着cookie也发送过去。
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; //在这里自己拼接一下Cookie，不用复制过来的那个GetCookie方法了，原来的那个写法还是比较严谨的 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> /// 获取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); //提交的请求主体的内容 request.ContentLength = postdatabyte.Length; //提交的请求主体的长度 request.AllowAutoRedirect = false; request.CookieContainer = cc; request.KeepAlive = true; //提交请求 Stream stream; stream = request.GetRequestStream(); stream.Write(postdatabyte, 0, postdatabyte.Length); //带上请求主体 stream.Close(); //接收响应 response = (HttpWebResponse)request.GetResponse(); //正式发起请求 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> /// 获取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; } }}这样获取到的就是登录之后的页面了。
三、模拟表单提交
再来一个例子，运用HttpWebRequest来模拟表单的提交，先新建一个MVC项目，里面只有这些代码：
[HttpPost] public ActionResult Index(string userName,string userPassword) { string str = "你提交过来的用户名是:" + userName + ",密码是: " + userPassword; Response.Write(str); return View(); }然后启动该项目，再新建另外一个项目,用于模拟提交表单，然后注意路径填写的是刚才建的那个MVC项目。
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表单里的信息 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); //设置请求主体的内容 stream.Close(); //接收响应 response = (HttpWebResponse)request.GetResponse(); Console.WriteLine(); Stream stream1 = response.GetResponseStream(); StreamReader sr = new StreamReader(stream1); Console.WriteLine(sr.ReadToEnd()); Console.ReadKey(); }输出结果如下所示：
四、模拟上传
血的教训，注意路径不能写错，否则在对流进行操作时，Write，就会报错：
HttpWebRequest request = (HttpWebRequest)WebRequest.Create("http://localhost:9170/upload/test");客户端：
class Program { /** * 如果要在客户端向服务器上传文件，我们就必须模拟一个POST multipart/form-data类型的请求 * Content-Type必须是multipart/form-data。 * 以multipart/form-data编码的POST请求格式与application/x-www-form-urlencoded完全不同 * multipart/form-data需要首先在HTTP请求头设置一个分隔符,例如7d4a6d158c9： * 我们模拟的提交要设定 content-type不同于非含附件的post时候的content-type * 这里需要： ("Content-Type", "multipart/form-data; boundary=ABCD"); * 然后，将每个字段用“--7d4a6d158c9”分隔，最后一个“--7d4a6d158c9--”表示结束。 * 例如，要上传一个title字段"Today"和一个文件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 * 如果是图片Content-Type: application/octet-stream * \r\n\r\n * <这里是1.txt文件的内容> * --7d4a6d158c9 * \r\n * 请注意，每一行都必须以\r\n结束value前面必须有2个\r\n，包括最后一行。 */ static void Main(string[] args) { string boundary = "----------" + DateTime.Now.Ticks.ToString("x");//元素分割标记 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前面必须有2个换行 HttpWebRequest request = (HttpWebRequest)WebRequest.Create("http://localhost:9170/upload/test"); request.ContentType = "multipart/form-data; boundary=" + boundary;//其他地方的boundary要比这里多-- 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请求总长度 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(); }
}测试服务器端地址：
public ActionResult Test() { HttpRequest request = System.Web.HttpContext.Current.Request; HttpFileCollection FileCollect = request.Files; if (FileCollect.Count > 0) //如果集合的数量大于0 { foreach (string str in FileCollect) { HttpPostedFile FileSave = FileCollect[str]; //用key获取单个文件对象HttpPostedFile string imgName = DateTime.Now.ToString("yyyyMMddhhmmss"); string AbsolutePath = FileSave.FileName; FileSave.SaveAs(AbsolutePath); //将上传的东西保存 } } return Content("键值对数目：" + FileCollect.Count); }参考：http://blog.csdn.net/youaregoo/article/details/8780709
其实还有很多东西的，比如模拟下载等等。这个留到以后用到再研究了。
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