C#实现Post数据或文件到指定的服务器进行接收_C#

应用场景

不同的接口服务器处理不同的应用，我们会在实际应用中将a服务器的数据提交给b服务器进行数据接收并处理业务。

比如我们想要处理一个office文件，由用户上传到a服务器，上传成功后，由b服务器负责进行数据处理和下载工作，这时我们就需要 post a服务器的文件数据到b服务器进行处理。

实现原理

将用户上传的数据或a服务器已存在的数据，通过form-data的形式post到b服务器，b服务由指定ashx文件进行数据接收，并转由指定的业务逻辑程序进行处理。如下图：

实现代码

postanywhere类

创建一个 postanywhere 类，

该类具有如下属性：

（1）public string posturl 要提交的服务器url

（2）public list<postfileitem> postdata 要准备的数据(postfileitem类可包括数据和文件类型)

该类包含的关键方法如下：

（1）public void addtext(string key, string value)

该方法将指定的字典数据加入到postdata中

（2）public void addfile(string name, string srcfilename, string desname, string contenttype = "text/plain")

该方法将指定的文件添加到postdata中，其中 srcfilename 表示要添加的文件名，desname表示接收数据生成的文件名

（3）public string send()

该方法将开始post传送数据

代码如下：

    public class postanywhere
    {
        public string posturl { get; set; }
        public list<postfileitem> postdata { get; set; }
 
        public postanywhere()
        {
            this.postdata = new list<postfileitem>();
        }
 
        public void addtext(string key, string value)
        {
            this.postdata.add(new postfileitem { name = key, value = value });
        }
 
        public void addfile(string name, string srcfilename, string desname,string at, string contenttype = "text/plain")
        {
            string[] srcname = path.getfilename(srcfilename).split('.');
            string exname = "";
            if (srcname.length > 1)
            {
                exname = "."+srcname[srcname.length-1];
            }
            
            this.posturl = "https://www.xxx.com/test.ashx?guid=" + desname;
            readyfile(name, getbinarydata(srcfilename), exname,contenttype);
        }
         void readyfile(string name, byte[] filebytes, string fileexname = "", string contenttype = "text/plain")
        {
            this.postdata.add(new postfileitem
            {
                type = postfileitemtype.file,
                name = name,
                filebytes = filebytes,
                filename = fileexname,
                contenttype = contenttype
            });
        }
 
        public string send()
        {
            var boundary = "----------------------------" + datetime.now.ticks.tostring("x");
            var request = (httpwebrequest)webrequest.create(this.posturl);
            request.contenttype = "multipart/form-data; boundary=" + boundary;
            request.method = "post";
            request.keepalive = true;
 
            stream memstream = new system.io.memorystream();
            var boundarybytes = system.text.encoding.ascii.getbytes("\r\n--" + boundary + "\r\n");
            var endboundarybytes = system.text.encoding.ascii.getbytes("\r\n--" + boundary + "--");
 
            var formdatatemplate = "\r\n--" + boundary + "\r\ncontent-disposition: form-data; name=\"{0}\";\r\n\r\n{1}";
 
            var formfields = this.postdata.where(m => m.type == postfileitemtype.text).tolist();
            foreach (var d in formfields)
            {
                var textbytes = system.text.encoding.utf8.getbytes(string.format(formdatatemplate, d.name, d.value));
                memstream.write(textbytes, 0, textbytes.length);
            }
 
            const string headertemplate = "content-disposition: form-data; name=\"{0}\"; filename=\"{1}\"\r\ncontent-type: {2}\r\n\r\n";
            var files = this.postdata.where(m => m.type == postfileitemtype.file).tolist();
            foreach (var fe in files)
            {
                memstream.write(boundarybytes, 0, boundarybytes.length);
                var header = string.format(headertemplate, fe.name, fe.filename ?? "system.byte[]", fe.contenttype ?? "text/plain");
                var headerbytes = system.text.encoding.utf8.getbytes(header);
                memstream.write(headerbytes, 0, headerbytes.length);
                memstream.write(fe.filebytes, 0, fe.filebytes.length);
            }
            memstream.write(endboundarybytes, 0, endboundarybytes.length);
            request.contentlength = memstream.length;
 
            httpwebresponse response;
 
            try
            {
                using (var requeststream = request.getrequeststream())
                {
                    memstream.position = 0;
                    var tempbuffer = new byte[memstream.length];
                    memstream.read(tempbuffer, 0, tempbuffer.length);
                    memstream.close();
                    requeststream.write(tempbuffer, 0, tempbuffer.length);
                }
                response = (httpwebresponse)request.getresponse();
            }
            catch (webexception webexception)
            {
                response = (httpwebresponse)webexception.response;
            }
 
            if (response == null)
            {
                throw new exception("httpwebresponse is null");
            }
 
            var responsestream = response.getresponsestream();
            if (responsestream == null)
            {
                throw new exception("responsestream is null");
            }
 
            using (var streamreader = new streamreader(responsestream))
            {
                return streamreader.readtoend();
            }
        }
    }
 
    public class postfileitem
    {
        public postfileitem()
        {
            this.type = postfileitemtype.text;
        }
 
        public postfileitemtype type { get; set; }
        public string value { get; set; }
        public byte[] filebytes { get; set; }
        public string name { get; set; }
        public string filename { get; set; }
        public string contenttype { get; set; }
    }
 
    public enum postfileitemtype
    {
        text = 0,
        file = 1
    }
    public byte[] getbinarydata(string filename)
		{
			if(!file.exists(filename))
			{
				return null;
			}
			try
			{
				filestream fs = new filestream(filename, filemode.open, fileaccess.read);
				byte[] imagedata = new byte[fs.length];
				fs.read( imagedata, 0,convert.toint32(fs.length));
				fs.close();
				return imagedata;
			}
			catch(exception)
			{
				return null;
			}
			finally
			{
				
			}
		}

ashx文件部署

在b服务器上部署ashx文件接收数据，ashx程序即，一般处理程序（httphandler），一个httphandler接受并处理一个http请求，需要实现ihttphandler接口，这个接口有一个isreusable成员，一个待实现的方法processrequest(httpcontextctx) 。.ashx程序适合产生供浏览器处理的、不需要回发处理的数据格式。

示例代码如下：

<%@ webhandler language="c#" class="handler" %>
 
using system;
using system.web;
using system.io;
 
public class handler : ihttphandler {
    
public void processrequest (httpcontext context) {
   if (context.request.files.count > 0)
   {
      string strpath = system.web.httpcontext.current.server.mappath("~/app_data/test/");
      string strname = context.request.files[0].filename;
      string ext=path.getextension(strname);
      string filename =httpcontext.current.request.querystring["guid"].tostring()+path.getfilenamewithoutextension(strname);
      if(ext!=""){
         filename = filename  + ext;
      }
      context.request.files[0].saveas(system.io.path.combine(strpath, filename));
   }
}
 
public bool isreusable {
   get {
      return false;
   }
}
 
}