如何通过 HTTP 协议和 C++ 上传文件？

Question

I'm going to upload files with C++, to a Java spring boot web server.我将使用 C++ 将文件上传到 Java spring 启动 Z2567A5EC9705EB7AC2ZC9 服务器。

I constructed the protocol looks like below (in plain text):我构建的协议如下所示（纯文本）：

POST /gallery/multimedia/uploadvideo HTTP/1.1
Host: 192.168.0.133:8981
Content-Type: multipart/form-data; boundary=------boundary1804289383
Connection: keep-alive

--------boundary1804289383
Content-Type: video/mp4
Content-Disposition: form-data; name="file"; filename="1.mp4"
Content-Length: 948611
Content-Transfer-Encoding: 8bit

... binary video data here ...

--------boundary1804289383--

The server side is Java spring boot server, interface defined as below:服务器端为 Java spring 启动服务器，接口定义如下：

@PostMapping("uploadvideo")
public ResultVo uploadVideo(@RequestParam("file") MultipartFile file);

While posting file, the server responses with code 400, and complains that发布文件时，服务器以代码 400 响应，并抱怨

Required request part 'file' is not present所需的请求部分“文件”不存在

However with a simple HTML page, file uploaded successfully, the HTML page listed below:但是通过一个简单的 HTML 页面，文件上传成功，HTML 页面如下：

<html>
    <head></head>
    <body>
        <form id="form" enctype="multipart/form-data" method="post" 
            action="http://192.168.0.133:8981/gallery/multimedia/uploadvideo">
            <input id="file" name="file" type="file" />
            <input id="submit" value="submit" type="submit" />
        </form>
    </body>
</html>

What do I miss?我想念什么？

Edit:编辑：

I've tried Postman/Chrome console/curl, all these tools only print the request looks like:我试过 Postman/Chrome 控制台/curl，所有这些工具只打印请求，如下所示：

# this is from curl
POST /gallery/multimedia/uploadvideo HTTP/1.1
User-Agent: curl/7.29.0
Host: 192.168.0.133:8981
Accept: */*
Content-Length: 187
Expect: 100-continue
Content-Type: multipart/form-data; boundary=----------------------------3c653d03b97f

How should I construct the file part?我应该如何构建文件部分？ Any ideas?有任何想法吗？

Answer 1

Firstly, thanks for @strupo 's suggestion.首先，感谢@strupo 的建议。

By turning on --trace option of curl and viewing the output log file, I finally fixed this problem.通过打开curl的--trace选项，查看output日志文件，终于解决了这个问题。

In curl , it posts file by several packets:在curl中，它通过几个数据包发布文件：

The header: header：

POST /gallery/multimedia/uploadvideo HTTP/1.1
User-Agent: curl/7.29.0
Host: 192.168.0.133:8981
Accept: */*
Content-Length: 13602  # you have to calculate content length first
Expect: 100-continue   # very important line
Content-Type: multipart/form-data; boundary=------3c653d03b97f

then it waits for server response:然后它等待服务器响应：

HTTP/1.1 100

after server responsed code 100, it sends data content, the form-data header goes first:服务器响应代码 100 后，它发送数据内容，表单数据 header 先行：

--------3c653d03b97f
Content-Type: video/mp4
Content-Disposition: form-data; name="file"; filename="1.mp4"
Content-Length: 6640
Content-Transfer-Encoding: 8bit

and file content follows, (in my case, a large memory is allocated, read from file and write to socket in once), and next file.然后是文件内容（在我的情况下，分配了一个大的 memory，从文件中读取并写入一次套接字），以及下一个文件。

Finally the protocol should finished with boundary line:最后，协议应该以边界线结束：

--------3c653d03b97f--

The Content-Length should include all bytes being sent after header. Content-Length应包括在 header 之后发送的所有字节。 The boundary should be prefixed with -- in file part. boundary应在文件部分以--为前缀。 Also the \r\n everywhere should be noticed.还应注意各处的\r\n 。

如何通过 HTTP 协议和 C++ 上传文件？

问题描述

1 个解决方案

解决方案1
1 已采纳 2020-12-08 07:51:15

如何通过 HTTP 协议和 C++ 上传文件？

问题描述

1 个解决方案

解决方案1 1 已采纳 2020-12-08 07:51:15

解决方案1
1 已采纳 2020-12-08 07:51:15