Home Backend Development PHP Tutorial 为什么上传文件时要设置为“multipart/form-data”

为什么上传文件时要设置为“multipart/form-data”

Jun 06, 2016 pm 08:49 PM
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上传文件时要设置为“multipart/form-data”是因为此类型不适合用于传输大型二进制数据或者包含非ASCII字符的数据。

为什么上传文件时要设置为“multipart/form-data”

Content-Type是什么?

Content-Type 实体头部用于指示资源的MIME类型 media type 。

在响应中,Content-Type标头告诉客户端实际返回的内容的内容类型。浏览器会在某些情况下进行MIME查找,并不一定遵循此标题的值; 为了防止这种行为,可以将标题 X-Content-Type-Options 设置为 nosniff。

Content-Type的句法示例:

Content-Type: text/html; charset=utf-8
Content-Type: multipart/form-data; boundary=something
Copy after login

为什么上传文件时要设置为“multipart/form-data”?

我们知道上传文件的时候media-type要设置为 multipart/form-data ,这是为什么呢?为什么不已有使用application/x-www-form-urlencoded呢?

因为此类型不适合用于传输大型二进制数据或者包含非ASCII字符的数据。平常我们使用这个类型都是把表单数据使用url编码后传送给后端,二进制文件当然没办法一起编码进去了。所以multipart/form-data就诞生了,专门用于有效的传输文件。

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