确定byte []是否为pdf文件 [英] Determine if a byte[] is a pdf file

问题描述

有没有办法检查byte []是否为pdf而无需打开?

Is there any way of checking if a byte[] is a pdf without opening?

我有一些代码可以将byte []列表显示为pdf缩略图.我以前知道所有的byte []都是pdf的，因为我们过滤了servlet以便仅返回它们.现在要求已更改，我需要恢复所有文件类型.有什么方法可以检查byte []是什么，或更具体地确定它是否不是pdf?

I have some code to display a list of byte[] as pdf thumbnails. I previously knew all the byte[] were pdf's because we filtered the servlet to only return these. Now the requirement has changed and I need to bring all file types back. Is there any way of checking what the byte[] is, or more specifically determining if it isn't, a pdf?

推荐答案

检查数组的前4个字节.

Check the first 4 bytes of the array.

如果这些文件是0x25 0x50 0x44 0x46，则很可能是PDF文件.

If those are 0x25 0x50 0x44 0x46 then it's most probably a PDF file.

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