.Net模拟提交表单

2016-09-0210:49:20

　　以中邮速递API为服务接口，由于提交方式为表单提交，我要获取返回值来处理其他业务，所以一开始尝试采用Js后台获取返回值，但是涉及到跨域请求限制问题，那边服务端接口返回的是json而不能处理jsonp；所以开始着手考虑后台模拟提交表单；

　　网上开始查资料，对于后台提交表单的一些相关资料：

• 表单提交协议规定：

　　 对于含文件的表单提交，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)。

• 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。

• 内容模板：

　　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";

•  单个文件或文本的实体类：

/// <summary>
    /// 单个文件或键值
    /// </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 == )
                    return false;

                if (FileContent != null && FileContent.Length >  && 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; }
    }

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 FormSubmit(string url, List<FormItemModel> formItems, CookieContainer cookieContainer = null, string refererUrl = null, Encoding encoding = null, int timeOut = )
        {
            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 > ;
            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 == )
                        formdataBytes = Encoding.UTF8.GetBytes(formdata.Substring(, formdata.Length - ));
                    else
                        formdataBytes = Encoding.UTF8.GetBytes(formdata);
                    postStream.Write(formdataBytes, , formdataBytes.Length);

                    //写入文件内容
                    if (item.FileContent != null && item.FileContent.Length > )
                    {
                        using (var stream = item.FileContent)
                        {
                            byte[] buffer = new byte[];
                            int bytesRead = ;
                            while ((bytesRead = stream.Read(buffer, , buffer.Length)) != )
                            {
                                postStream.Write(buffer, , bytesRead);
                            }
                        }
                    }
                }
                //结尾
                var footer = Encoding.UTF8.GetBytes("\r\n--" + boundary + "--\r\n");
                postStream.Write(footer, , 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 = ;
                //直接写入流
                Stream requestStream = request.GetRequestStream();

                byte[] buffer = new byte[];
                int bytesRead = ;
                while ((bytesRead = postStream.Read(buffer, , buffer.Length)) != )
                {
                    requestStream.Write(buffer, , bytesRead);
                }
                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;
                }
            }
        }

public static Stream FileToStream(string fileName)
{
// 打开文件
FileStream fileStream = new FileStream(fileName, FileMode.Open, FileAccess.Read, FileShare.Read);
// 读取文件的 byte[]
byte[] bytes = new byte[fileStream.Length];
fileStream.Read(bytes, 0, bytes.Length);
fileStream.Close();
// 把 byte[] 转换成 Stream
Stream stream = new MemoryStream(bytes);
return stream;
}

• 调用实例，请求中邮速递API

   public static string FormSubmitDemo()
          {
              //中邮速递API
              var url = "http://captureupload.30post.cn/capture/index/idcard_upload";
              var log1 = @"C:\Users\fmh\Desktop\图片\1.jpg";
              var log2 = @"C:\Users\fmh\Desktop\图片\2.jpg";
              var formDatas = new List<FormItemModel>();
              //添加文件
              formDatas.Add(new FormItemModel()
              {
                  Key = "card_photo",
                  Value = "",
                  FileName = "1.jpg",
                  FileContent = FileToStream(log1)
              });
              formDatas.Add(new FormItemModel()
              {
                  Key = "card_photob",
                  Value = "",
                  FileName = "2.jpg",
                  FileContent = FileToStream(log2)
              });
              //添加文本
              formDatas.Add(new FormItemModel()
              {
                  Key = "name",
                  Value = "测试"
              });
              formDatas.Add(new FormItemModel()
              {
                  Key = "id_card",
                  Value = ""
              });
              formDatas.Add(new FormItemModel()
              {
                  Key = "mobile",
                  Value = ""
              });
              formDatas.Add(new FormItemModel()
              {
                  Key = "order_no",
                  Value = ""
              });
              //提交表单
              var result = FormSubmit(url, formDatas);
              return result;
          }