Add the following configuration in application. Properties

spring.thymeleaf.cache=false # close cache

Introduce debugging tools into POM. XML and set it to open

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-devtools</artifactId>
    <optional>true</optional>
</dependency>

alt + ctrl + S open settings：
Build,Execution,Deployment —— Complier：
Check Build project automatically
ctrl + shift + alt + /:
Check Registry
Check compiler.automake.allow.when.app.running