When developing the interface, it needs to be connected with the partner's interface, using the php language, and the partner's interface needs to be signed and verified by their rules, but the DEMO given is java. Don't know how to start. Do I need to write the java language into php? But I know little about the JAVA language.
The following is a signed demo. 
Supplementary sign method
![[Web front-end] Node.js quick start](https://img.php.cn/upload/course/000/000/067/662b5d34ba7c0227.png)
You can follow the demo he gave and write it in PHP. Also, did the questioner not post a complete demo? There should be a sign function.
This is an SDK. Logically speaking, a multi-language version of the SDK should be provided. If it is not provided, just rewrite it into PHP based on the logic of Java. Don't be afraid that the code does not have much logic, so just put it in Google and rewrite it. Just a copy of php is enough