HTTP请求中的Body构建——.NET客户端调用JAVA服务进行文件上传

PS：今日的第二篇，当日事还要当日毕:）

 

http的POST请求发送的内容在Body中，因此有时候会有我们自己构建body的情况。

JAVA使用http—post上传file时，spring框架中有HttpEntity类封装了http请求中的Body内容。JAVA客户端调用时非常方便，直接将File对象赋值进去就可以了。

C#中没有找到有类似的封装的（有发现的大神麻烦告知一声：）），HttpWebRequest是原始的http请求类，因此Body中的内容只能自己写入。

 

首先来看下http请求的内容：

---

POST /forwardOrder/applyRefund HTTP/1.1

Host: XXXX

Connection: keep-alive

Content-Length: 3478080

Cache-Control: max-age=0

Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8

Origin: http://192.168.1.115:3800

Upgrade-Insecure-Requests: 1

User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/45.0.2454.101 Safari/537.36

Content-Type: multipart/form-data; boundary=----WebKitFormBoundaryHUq1k5ZLV25EmvgR

Referer: http://192.168.1.115:3800/forwardOrder/refundOrder?id=160722103139001234

Accept-Encoding: gzip, deflate

Accept-Language: zh-CN,zh;q=0.8

Cookie: JSESSIONID=52F3D94B82F97240D5A4BBCA2FB08969;

 

------WebKitFormBoundaryHUq1k5ZLV25EmvgR

Content-Disposition: form-data; name="condition"

 

{"orderId":"160722103139001234","fileName":"C:\\fakepath\\12349.jpg"}

------WebKitFormBoundaryHUq1k5ZLV25EmvgR

Content-Disposition: form-data; name="file"; filename="12349.jpg"

Content-Type: image/jpeg

 

����

---

红色的是HttpHeader的内容，boundary定义了body的分割符。

蓝色的就是我们的Body了，每一个参数使用boundary来进行分割。

特殊的例如文件参数，需要加上Content-Type描述。

乱码部分就是我们的文件字节流了。

最后注意换行和空格的写入。

 

C#代码示例：

         /// <summary>
         /// 上传文件操作
         /// </summary>
         /// <param name="fileStream"> 文件流</param>
         /// <param name="url"> 上传地址</param>
         /// <param name="fileName"> 文件名</param>
         /// <param name="contenttype"> 上下文类型 </param>
         /// <returns> 返回值</returns>
         private Dictionary <string, string> UploadFileEx(Stream fileStream, string url, string fileName, string contenttype)
         {
             Dictionary<string , string> result = new Dictionary <string, string>();

             if ((contenttype == null ) || (contenttype.Length == ))
             {
                 contenttype = "application/octet-stream" ;
             }

             Uri uri = new Uri(url);
             string boundary = "----" + DateTime.Now.Ticks.ToString( "x");
             HttpWebRequest webrequest = (HttpWebRequest )WebRequest.Create(uri);
             webrequest.ContentType = "multipart/form-data; boundary=" + boundary;
             webrequest.Method = "POST";

             // 构建POST消息头，除文件之外的键值对都需要赋值
             StringBuilder sb = new StringBuilder();
             sb.AppendFormat( "--{0}", boundary);
             sb.AppendLine( string.Empty);
             sb.Append( "Content-Disposition: form-data; name=\"uptype\";" );
             sb.AppendLine( string.Empty);
             sb.AppendLine( string.Empty);
             sb.Append( "clbuss");
             sb.AppendLine( string.Empty);

             sb.AppendFormat( "--{0}", boundary);
             sb.AppendLine( string.Empty);
             sb.Append( "Content-Disposition: form-data; name=\"fileName\";" );
             sb.AppendLine( string.Empty);
             sb.AppendLine( string.Empty);
             sb.Append(fileName);
             sb.AppendLine( string.Empty);

             sb.AppendFormat( "--{0}", boundary);
             sb.AppendLine( string.Empty);
             sb.AppendFormat( "Content-Disposition: form-data; name=\"file\"; filename=\"{0}\"" , fileName);
             sb.AppendLine( string.Empty);
             sb.AppendFormat( "Content-Type: {0}", contenttype);
             sb.AppendLine( string.Empty);
             sb.AppendLine( string.Empty);

             string postHeader = sb.ToString();
             byte[] postHeaderBytes = Encoding .UTF8.GetBytes(postHeader);

             // 构建POST消息尾
             StringBuilder endSb = new StringBuilder();
             endSb.AppendLine( string.Empty);
             endSb.AppendFormat( "--{0}", boundary);
             byte[] boundaryBytes = Encoding .UTF8.GetBytes(endSb.ToString());
             long length = postHeaderBytes.Length + fileStream.Length + boundaryBytes.Length;
             webrequest.ContentLength = length;
             Stream requestStream = webrequest.GetRequestStream();

             // 写入消息头
             requestStream.Write(postHeaderBytes, , postHeaderBytes.Length);

             // 写入文件内容
             byte[] buffer = new byte[checked(( uint)Math .Min(, (int)fileStream.Length))];
             int bytesRead = ;

             while ((bytesRead = fileStream.Read(buffer, , buffer.Length)) != )
             {
                 requestStream.Write(buffer, , bytesRead);
             }

             // 写入消息尾
             requestStream.Write(boundaryBytes, , boundaryBytes.Length);
             WebResponse responce = webrequest.GetResponse();
             Stream s = responce.GetResponseStream();
             StreamReader sr = new StreamReader(s);
             string resStr = sr.ReadToEnd();
             Dictionary<string , object> resDic = JsonConvert.DeserializeObject<Dictionary <string, object>>(resStr);
             if (resDic["code" ].ToString() == "")
             {
                 Dictionary<string , string> resDetail = JsonConvert.DeserializeObject<Dictionary <string, string>>(resDic["content" ].ToString());
                 if (resDetail["code" ] == "")
                 {
                     result.Add( "issucess", "" );
                     result.Add( "address", BaseSysParamCache .GetSysParam("ShareUploadImgUrl") + resDetail["path" ]);
                 }
                 else
                 {
                     result.Add( "issucess", "" );
                     result.Add( "msg", resDetail["msg" ]);
                 }
             }
             else
             {
                 result.Add( "issucess", "" );
                 result.Add( "msg", resDic["message" ].ToString());
             }

             return result;
         }    

 

http请求对于JAVA和C#本身其实并无区分，只是使用的方式不同而已。

无论何种情况，源生的HTTP请求内容都是通用的。