C#記一次http協(xié)議multipart/form-data的boundary問題

更新時間：2022年06月09日 15:56:23 作者：地獄高速公路

這篇文章主要介紹了C#記一次http協(xié)議multipart/form-data的boundary問題，具有很好的參考價值，希望對大家有所幫助。如有錯誤或未考慮完全的地方，望不吝賜教

1.問題描述

使用post方法調(diào)用上級聯(lián)網(wǎng)廠家接口，返回http狀態(tài)碼415，返回信息Content type ‘application/x-www-form-urlencoded’ not supported

測試上級聯(lián)網(wǎng)廠家接口使用的是Postman工具，工具下載地址：https://www.getpostman.com/downloads/

使用application/x-www-form-urlencoded調(diào)用接口，返回http狀態(tài)碼415，如圖：

既然服務(wù)器無法處理請求附帶的媒體格式，那么改用multipart/form-data試試？

測試后發(fā)現(xiàn)可以調(diào)用成功，如圖：

我們都知道ContentType為application/x-www-form-urlencoded的請求頭、體如何構(gòu)造，如：

HttpWebRequest request = WebRequest.Create(new Uri(url)) as HttpWebRequest;
request.Method = "POST";
request.Host = Properties.Settings.Default.IP;
request.ContentType = "application/x-www-form-urlencoded; charset=UTF-8";
request.UserAgent = "Mozilla/5.0 (Windows NT 6.3; WOW64; Trident/7.0; rv:11.0) like Gecko";
request.Accept = "*/*";
request.CookieContainer = cc;
request.KeepAlive = true;
string postData = string.Format("action=cx&hphm={0}&hpzl=&jclb=&detlsh=&clpp=&clxh=&rlzl=&pfbz=&jcff=&evl=&staName={1}&detLineId=&syxz=&rqyi={2}&rqer={3}&RQXZ=JCRQ&CXJL=Jiance&cllb=&clgs=&zcrq=&zzl=&clsbdh=&syr=&ccdjrq=&page={4}&rows=10", hphm, staName, rqyi, rqer, page);
byte[] postdatabyte = Encoding.GetEncoding("utf-8").GetBytes(postData);
request.ContentLength = postdatabyte.Length;
using (Stream stream = request.GetRequestStream())
{
	stream.Write(postdatabyte, 0, postdatabyte.Length);
}
HttpWebResponse response = request.GetResponse() as HttpWebResponse;
using (StreamReader reader = new StreamReader(response.GetResponseStream(), Encoding.GetEncoding("utf-8")))
{
	string temp = reader.ReadToEnd();
}

但是！multipart/form-data的請求頭與請求體該如何構(gòu)造呢？像下面這樣？

string url = "http://112.17.158.12:8180/intf/services/query";
HttpWebRequest request = WebRequest.Create(new Uri(url)) as HttpWebRequest;
request.Method = "POST";
request.Host = "112.17.158.12:8180";
request.ContentType = "multipart/form-data; ";
request.UserAgent = "PostmanRuntime/7.17.1";
request.Accept = "*/*";
request.KeepAlive = true;
string postData = @"jkuser=33088102&jkpasswd=33088102&jsondata={""jkid"":""R10"",""requestTime"":""20190919110603"",""body"":[{""inspstationcode"":""33088102""}]}";
byte[] postdatabyte = Encoding.GetEncoding("utf-8").GetBytes(postData);
request.ContentLength = postdatabyte.Length;
using (Stream stream = request.GetRequestStream())
{
	stream.Write(postdatabyte, 0, postdatabyte.Length);
}
HttpWebResponse response = request.GetResponse() as HttpWebResponse;
using (StreamReader reader = new StreamReader(response.GetResponseStream(), Encoding.GetEncoding("utf-8")))
{
	string temp = reader.ReadToEnd();
}

顯然不對，捕獲到了"遠(yuǎn)程服務(wù)器返回錯誤:(500)內(nèi)部服務(wù)器錯誤。"異常，那么我們該怎么辦呢？

2.解決思路

既然Postman工具使用ContentType為multipart/form-data類型post數(shù)據(jù)可以成功，那么我們寫的C#程序應(yīng)該也可以呀！那怎么辦呢？。。。。沒錯??！就是抓包！

首先想到的是，用fiddler抓Postman的數(shù)據(jù)包，然后C#程序構(gòu)造同樣的數(shù)據(jù)包即可。

觀察數(shù)據(jù)包Headers選項卡，如圖：

發(fā)現(xiàn)Content-Type: multipart/form-data;后面跟了一個boundary=----------------------------183584948778966847113836

并且TextView選項卡如下：

WebForms選項卡如下：

所以，可以按照Headers和TextView選項卡內(nèi)容構(gòu)造post請求，就可以解決我們的問題了！

3.解決步驟

將ContentType加上boundary=boundary-------------------------xxxxxxxxxxxxxx

并且構(gòu)造參數(shù)，如下：

string url = "http://112.17.158.12:8180/intf/services/query";
string boundary = "--------------------------" + DateTime.Now.Ticks.ToString("x");
string boundary2 = "--" + boundary;
HttpWebRequest request = WebRequest.Create(new Uri(url)) as HttpWebRequest;
request.Method = "POST";
request.Host = "112.17.158.12:8180";
request.ContentType = "multipart/form-data; boundary=" + boundary;
request.UserAgent = "PostmanRuntime/7.17.1";
request.Accept = "*/*";
request.KeepAlive = true;
StringBuilder sb = new StringBuilder();
sb.Append(boundary2 + "\r\n");
sb.Append(@"Content-Disposition: form-data; name=""jkuser""" + "\r\n\r\n");
sb.Append("33088102" + "\r\n");
sb.Append(boundary2 + "\r\n");
sb.Append(@"Content-Disposition: form-data; name=""jkpasswd""" + "\r\n\r\n");
sb.Append("33088102" + "\r\n");
sb.Append(boundary2 + "\r\n");
sb.Append(@"Content-Disposition: form-data; name=""jsondata""" + "\r\n\r\n");
sb.Append(@"{""jkid"":""R10"",""requestTime"":""20190919110603"",""body"":[{""inspstationcode"":""33088102""}]}" + "\r\n");
sb.Append(boundary2 + "--" + "\r\n");
string postData = sb.ToString();
byte[] postdatabyte = Encoding.GetEncoding("utf-8").GetBytes(postData);
request.ContentLength = postdatabyte.Length;
using (Stream stream = request.GetRequestStream())
{
    stream.Write(postdatabyte, 0, postdatabyte.Length);
}
HttpWebResponse response = request.GetResponse() as HttpWebResponse;
using (StreamReader reader = new StreamReader(response.GetResponseStream(), Encoding.GetEncoding("utf-8")))
{
    string temp = reader.ReadToEnd();
}

值得注意的是，“boundary-------------------------xxxxxxxxxxxxxx”

這么長一串東西，只是作為分隔符出現(xiàn)的，不必太在意它是什么東西，我將它理解為分割文本參數(shù)的這么一個東西，并且通過仔細(xì)觀察發(fā)現(xiàn)可以發(fā)現(xiàn)header中contenttype的橫線數(shù)量比參數(shù)中橫線數(shù)量少兩個且必須少兩個？

以上為個人經(jīng)驗，希望能給大家一個參考，也希望大家多多支持腳本之家。

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