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