c# 模拟表单提交，post form 上传文件、大数据内容

表单提交协议规定：
要先将 HTTP 要求的 Content-Type 设为 multipart/form-data，而且要设定一个 boundary 参数，
这个参数是由应用程序自行产生，它会用来识别每一份资料的边界 (boundary)，
用以产生多重信息部份 (message part)。
而 HTTP 服务器可以抓取 HTTP POST 的信息，


基本内容：
1. 每个信息部份都要用 --[BOUNDARY_NAME] 来包装，以分隔出信息的每个部份，而最后要再加上一个 --[BOUNDARY_NAME] 来表示结束。
2. 每个信息部份都要有一个 Content-Disposition: form-data; name=""，而 name 设定的就是 HTTP POST 的键值 (key)。
3. 声明区和值区中间要隔两个新行符号（\r\n）。
4. 中间可以夹入二进制资料，但二进制资料必须要格式化为二进制字符串。
5. 若要设定不同信息段的资料型别 (Content-Type)，则要在信息段内的声明区设定。


两个form内容模板
boundary = "----" + DateTime.Now.Ticks.ToString("x");//程序生成
1.文本内容
"\r\n--" + boundary +
"\r\nContent-Disposition: form-data; name=\"键\"; filename=\"文件名\"" +
"\r\nContent-Type: application/octet-stream" +
"\r\n\r\n";
2.文件内容
"\r\n--" + boundary +
"\r\nContent-Disposition: form-data; name=\"键\"" +

"\r\n\r\n内容";

代码
1.表示一个表单项的对象

/// <summary>/// 表单数据项/// </summary>public class FormItemModel{/// <summary>/// 表单键，request["key"]/// </summary>public string Key { set; get; }/// <summary>/// 表单值,上传文件时忽略，request["key"].value/// </summary>public string Value { set; get; }/// <summary>/// 是否是文件/// </summary>public bool IsFile{get{if (FileContent==null || FileContent.Length == 0)return false;if (FileContent != null && FileContent.Length > 0 && string.IsNullOrWhiteSpace(FileName))throw new Exception("上传文件时 FileName 属性值不能为空");return true;}}/// <summary>/// 上传的文件名/// </summary>public string FileName { set; get; }/// <summary>/// 上传的文件内容/// </summary>public Stream FileContent { set; get; }}

2.提交表单主逻辑实现

/// <summary>/// 使用Post方法获取字符串结果/// </summary>/// <param name="url"></param>/// <param name="formItems">Post表单内容</param>/// <param name="cookieContainer"></param>/// <param name="timeOut">默认20秒</param>/// <param name="encoding">响应内容的编码类型（默认utf-8）</param>/// <returns></returns>public static string PostForm(string url, List<FormItemModel> formItems, CookieContainer cookieContainer = null, string refererUrl = null, Encoding encoding = null,int timeOut = 20000){HttpWebRequest request = (HttpWebRequest)WebRequest.Create(url);#region 初始化请求对象request.Method = "POST";request.Timeout = timeOut;request.Accept = "text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8";request.KeepAlive = true;request.UserAgent = "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/31.0.1650.57 Safari/537.36";if (!string.IsNullOrEmpty(refererUrl))request.Referer = refererUrl;if (cookieContainer != null)request.CookieContainer = cookieContainer;#endregionstring boundary = "----" + DateTime.Now.Ticks.ToString("x");//分隔符request.ContentType = string.Format("multipart/form-data; boundary={0}", boundary);//请求流var postStream = new MemoryStream();#region 处理Form表单请求内容//是否用Form上传文件var formUploadFile = formItems != null && formItems.Count > 0;if (formUploadFile){//文件数据模板string fileFormdataTemplate ="\r\n--" + boundary +"\r\nContent-Disposition: form-data; name=\"{0}\"; filename=\"{1}\"" +"\r\nContent-Type: application/octet-stream" +"\r\n\r\n";//文本数据模板string dataFormdataTemplate ="\r\n--" + boundary +"\r\nContent-Disposition: form-data; name=\"{0}\"" +"\r\n\r\n{1}";foreach (var item in formItems){string formdata = null;if (item.IsFile){//上传文件formdata = string.Format(fileFormdataTemplate,item.Key, //表单键item.FileName);}else{//上传文本formdata = string.Format(dataFormdataTemplate,item.Key,item.Value);}//统一处理byte[] formdataBytes = null;//第一行不需要换行if (postStream.Length == 0)formdataBytes = Encoding.UTF8.GetBytes(formdata.Substring(2, formdata.Length - 2));elseformdataBytes = Encoding.UTF8.GetBytes(formdata);postStream.Write(formdataBytes, 0, formdataBytes.Length);//写入文件内容if (item.FileContent != null && item.FileContent.Length>0){using (var stream = item.FileContent){byte[] buffer = new byte[1024];int bytesRead = 0;while ((bytesRead = stream.Read(buffer, 0, buffer.Length)) != 0){postStream.Write(buffer, 0, bytesRead);}}}}//结尾var footer = Encoding.UTF8.GetBytes("\r\n--" + boundary + "--\r\n");postStream.Write(footer, 0, footer.Length);}else{request.ContentType = "application/x-www-form-urlencoded";}#endregionrequest.ContentLength = postStream.Length;#region 输入二进制流if (postStream != null){postStream.Position = 0;//直接写入流Stream requestStream = request.GetRequestStream();byte[] buffer = new byte[1024];int bytesRead = 0;while ((bytesRead = postStream.Read(buffer, 0, buffer.Length)) != 0){requestStream.Write(buffer, 0, bytesRead);}////debug//postStream.Seek(0, SeekOrigin.Begin);//StreamReader sr = new StreamReader(postStream);//var postStr = sr.ReadToEnd();postStream.Close();//关闭文件访问}#endregionHttpWebResponse response = (HttpWebResponse)request.GetResponse();if (cookieContainer != null){response.Cookies = cookieContainer.GetCookies(response.ResponseUri);}using (Stream responseStream = response.GetResponseStream()){using (StreamReader myStreamReader = new StreamReader(responseStream, encoding ?? Encoding.UTF8)){string retString = myStreamReader.ReadToEnd();return retString;}}}

3.调用模拟post表单

var url = "http://127.0.0.1/testformdata.aspx?aa=1&bb=2&ccc=3";var log1=@"D:\temp\log1.txt";var log2 = @"D:\temp\log2.txt";var formDatas = new List<Grass.Net.FormItemModel>();//添加文件formDatas.Add(new Grass.Net.FormItemModel(){Key="log1",Value="",FileName = "log1.txt",FileContent=File.OpenRead(log1)});formDatas.Add(new Grass.Net.FormItemModel(){Key = "log2",Value = "",FileName = "log2.txt",FileContent = File.OpenRead(log2)});//添加文本formDatas.Add(new Grass.Net.FormItemModel(){Key = "id",Value = "id-test-id-test-id-test-id-test-id-test-"});formDatas.Add(new Grass.Net.FormItemModel(){Key = "name",Value = "name-test-name-test-name-test-name-test-name-test-"});//提交表单var result = PostForm(url, formDatas);