HTTP文件上传如何工作？ [英] How does HTTP file upload work?

问题描述

 < form enctype =multipart / form- dataaction =http：// localhost：3000 / upload？upload_progress_id = 12344method =POST> 
< input type =hiddenname =MAX_FILE_SIZEvalue =100000/> 
选择要上传的文件：< input name =uploadedfiletype =file/>< br /> 
< input type =submitvalue =Upload File/> 
< / form> 
  

它如何在内部发送文件？该文件是否作为数据的HTTP身体的一部分发送？在这个请求的头文件中，我没有看到与文件名相关的任何内容。

我只是想知道发送文件时HTTP的内部工作方式。 解决方案

<$ p $

p> POST / upload？upload_progress_id = 12344 HTTP / 1.1
Host：localhost：3000
Content-Length：1325
Origin：http：// localhost：3000
...其他标题...
Content-Type：multipart / form-data; border = ---- WebKitFormBoundaryePkpFF7tjBAqx29L

------ WebKitFormBoundaryePkpFF7tjBAqx29L
Content-Disposition：form-data; name =MAX_FILE_SIZE

100000
------ WebKitFormBoundaryePkpFF7tjBAqx29L
Content-Disposition：form-data; NAME = UploadedFile的; filename =hello.o
Content-Type：application / x-object

...文件内容放在这里...
------ WebKitFormBoundaryePkpFF7tjBAqx29L -


代替表单参数的URL编码，表单参数（包括文件数据）被发送在上面的例子中，你可以看到输入 MAX_FILE_SIZE Content-Disposition 标题的一部分。

完整的详细信息是这里。

When I submit a simple form like this with a file attached:

<form enctype="multipart/form-data" action="http://localhost:3000/upload?upload_progress_id=12344" method="POST">
<input type="hidden" name="MAX_FILE_SIZE" value="100000" />
Choose a file to upload: <input name="uploadedfile" type="file" /><br />
<input type="submit" value="Upload File" />
</form>

How does it send the file internally? Is the file sent as part of the HTTP body as data? In the headers of this request, I don't see anything related to the name of the file.

I just would like the know the internal workings of the HTTP when sending a file.

解决方案

Let's take a look at what happens when you select a file and submit your form (I've truncated the headers for brevity):

POST /upload?upload_progress_id=12344 HTTP/1.1
Host: localhost:3000
Content-Length: 1325
Origin: http://localhost:3000
... other headers ...
Content-Type: multipart/form-data; boundary=----WebKitFormBoundaryePkpFF7tjBAqx29L

------WebKitFormBoundaryePkpFF7tjBAqx29L
Content-Disposition: form-data; name="MAX_FILE_SIZE"

100000
------WebKitFormBoundaryePkpFF7tjBAqx29L
Content-Disposition: form-data; name="uploadedfile"; filename="hello.o"
Content-Type: application/x-object

... contents of file goes here ...
------WebKitFormBoundaryePkpFF7tjBAqx29L--

Instead of URL encoding the form parameters, the form parameters (including the file data) are sent as sections in a multipart document in the body of the request.

In the example above, you can see the input MAX_FILE_SIZE with the value set in the form, as well as a section containing the file data. The file name is part of the Content-Disposition header.

The full details are here.

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