HLCode Miniprogram PDF Download

Problem Context

Some WeChat miniprograms only allow PDF preview and do not expose a direct download button, such as file preview pages from HLCode / hlcode.cn. Engineers may have only a #miniprogram://... protocol link or a long preview.hlcode.cn URL. In a browser, the page can render the document but not reliably return the original file, while manual packet capture can miss key parameters.

How It Works

The skill turns “preview page to downloadable file” into explicit steps: identify the link type, extract parameters such as id, name, type, and time, call the backend API to obtain the real download URL, then download and validate the file.
- Preferred input: an H5 preview URL like https://preview.hlcode.cn/?....
- Miniprogram link: #miniprogram://HLCode/xxx must be converted to an H5 link or captured from the preview request.
- Key call: use id to request POST /qruser/file/get_url_byid, then read data.url.
- Validation: check file size, Content-Type as application/pdf, and the %PDF- magic bytes.
- Scope: the same flow can be used when type is word, excel, or ppt.

Boundaries

This flow targets HLCode miniprogram file downloads and is not a general miniprogram decompiler. The time parameter may expire, but the API call usually depends on a valid id. If the response is HTML, code: 1, or code: 500, re-check the link, file status, or parameter extraction. URL-encoded Chinese file names must be decoded before display.