步驟很簡單，只需要變更一下pom檔案。

1. Maven新增依賴

將下邊的依賴新增到你的pom檔案中去

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

2. 實現熱載入

• 在Eclipse中，儲存檔案會自動觸發熱載入
• 在IDEA中，需要build project來觸發熱載入，快捷鍵是Ctrl+F9

官方文件：As DevTools monitors classpath resources, the only way to trigger a restart is to update the classpath. The way in which you cause the classpath to be updated depends on the IDE that you are using. In Eclipse, saving a modified file causes the classpath to be updated and triggers a restart. In IntelliJ IDEA, building the project (Build -> Build Project) has the same effect.

3. 注意

• 如果你的專案是通過java命令（java -jar）或者某個特殊的類載入器啟動的，spring-boot 的Developer tools會認為這是生產環境而自動失效