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

/// 
/// 表单数据项
/// 
public class FormItemModel
{
	/// 
	/// 表单键,request["key"]
	/// 
	public string Key { set; get; }
	/// 
	/// 表单值,上传文件时忽略,request["key"].value
	/// 
	public string Value { set; get; }
	/// 
	/// 是否是文件
	/// 
	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;
		}
	}
	/// 
	/// 上传的文件名
	/// 
	public string FileName { set; get; }
	/// 
	/// 上传的文件内容
	/// 
	public Stream FileContent { set; get; }
}

2.提交表单主逻辑实现

/// 
/// 使用Post方法获取字符串结果
/// 
/// 
/// Post表单内容
/// 
/// 默认20秒
/// 响应内容的编码类型(默认utf-8)
/// 
public static string PostForm(string url, List 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();
//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);




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