转自：https://www.cnblogs.com/DoNetCShap/p/10696277.html
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";
/// <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 == )
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; }
}
/// <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 = )
{
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);
} ////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;
}
}
}
运行方式：
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);
以下内容做了一些优化修改：
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}";
//头部
var header = Encoding.UTF8.GetBytes("--" + boundary);
postStream.Write(header, , header.Length);
var index = ;
foreach (var item in formItems)
{
index++;
string formdata = null;
if (item.IsFile)
{
if (index == )
{
formdata = string.Format("\r\nContent-Disposition: form-data; name=\"{0}\"; filename=\"{1}\"\r\nContent-Type: application/octet-stream\r\n\r\n", item.Key, item.FileName); }
else
{
//上传文件
formdata = string.Format(fileFormdataTemplate,item.Key,item.FileName); } }
else
{
if (index==)
{
formdata = string.Format("\r\nContent-Disposition: form-data; name=\"{0}\"\r\n\r\n{1}", item.Key, item.FileName);
}
else
{
//上传文本
formdata = string.Format(dataFormdataTemplate, item.Key, item.Value);
} } //统一处理
byte[] formdataBytes = Encoding.UTF8.GetBytes(formdata); postStream.Write(formdataBytes, , formdataBytes.Length); //写入文件内容
//if (item.FileContent != null && item.FileContent.Length > 0)
if (item.IsFile)
{ FileStream fs = new FileStream(item.FilePath, FileMode.Open, FileAccess.Read);//可以是其他重载方法
byte[] byData = new byte[fs.Length];
fs.Read(byData, , byData.Length);
fs.Close();
postStream.Write(byData, , byData.Length);
}
}
//结尾
var footer = Encoding.UTF8.GetBytes("\r\n--" + boundary + "--");
postStream.Write(footer, , footer.Length); }