1.psd file is in the file format of Photoshop and cannot be displayed directly by the browser. There is a need to generate a preview of the psd file. I searched on Google for a few days but could not find the available code, so I researched it myself and finally found it. The solution is to export the psd to a jpg file first and then generate a thumbnail of it, it will be much easier.
2. You need to use an open source library of PHP: imagemagick. Installation method: Search "ImageMagick php windows installation" in Google. Of course, if you are Linux, just replace Windows with Linux.
3. After installation, the key is how to use it. After a few hours of tossing, the conversion was finally achieved. It is very simple:
$mw= NewMagickWand();
MagickReadImage($mw, 123.psd);
MagickResetIterator($mw);
MagickWriteImage($mw, "123.jpg");