If it is IDEA before 2018.3, please refer to: https://blog.csdn.net/forezp/article/details/76408139
If it is a version after IDEA 2018.3, please use the following method:
1. Click Edit Configurations..
2. Find the project you want to start multiple times and check (allow parallel operation). Allow parallel run
3. By modifying the application.yml file server.port , then start it. Multiple instances need to modify multiple ports to start.