I haven't done anything specific these days. The backstage said I didn't care if I was doing it, but I haven't succeeded for several days. I read the official documents and other projects myself. I found that most of the signatures were done backstage, so I recorded them to prevent similar situations from happening again in the future. Summarized the following points.

1. First, confirm whether the prepaid order in the background corresponds to the attribute value in the WeChat payment object PayReq.

2. Confirm the value of the symbol. The payment object in WeChat has a sing attribute, which is signature. The value of this attribute is special, and it can only be used directly after the secondary signature is completed in the background. If the secondary signature is not done in the background and needs to be done by ourselves, we need to use a method to deal with the symbol value.

3.MD5 encryption