1.首先加入开发工具依赖

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

2.其次在build maven插件中开启热部署

<build><plugins><plugin><groupId>org.springframework.boot</groupId><artifactId>spring-boot-maven-plugin</artifactId><configuration><fork>true</fork> #主要是这里，开启</configuration></plugin></plugins>
</build>

3.idea开启自动

4.勾选compiler.automake.allow.when.app.running