C# POST 表单发送文件
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; #endregion string 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)); else formdataBytes = 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"; } #endregion request.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 } #endregion HttpWebResponse 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);
