Hot deployment eliminates the need for full application restarts when modifying source files by dynamically reloading only the updated compiled classes or templates, boosting development efficiency.

Maven Spring Loaded Plugin

Add the Spring Loaded dependency to the spring-boot-maven-plugin section of your pom.xml:

<build>
    <plugins>
        <plugin>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-maven-plugin</artifactId>
            <dependencies>
                <dependency>
                    <groupId>org.springframework</groupId>
                    <artifactId>springloaded</artifactId>
                    <version>1.2.5.RELEASE</version>
                </dependency>
            </dependencies>
        </plugin>
    </plugins>
</build>

Launch the application using mvn spring-boot:run. After modifying a controller or HTML file, press Ctrl+Shift+F9 in IntelliJ IDEA to reload the updated class and refresh the browser to see changes.

Note: This method works only with mvn spring-boot:run, not by diretcly running Application.java.

Required IDE and Configuration Checks

1. Ensure IntelliJ IDEA has automatic compilation enabled: Go to Preferences > Compiler and check Build project automatically.
2. If using Thymeleaf, disable template caching in application.properties to reflect HTML changes:

# Disable Thymeleaf cache for development (set to true in production)
spring.thymeleaf.cache=false

Spring Boot DevTools Depednency

Add the DevTools hot deployment module to pom.xml:

<!-- Hot deployment module -->
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-devtools</artifactId>
    <optional>true</optional> <!-- Required for hot deployment to work -->
</dependency>

Restart the application (either via mvn spring-boot:run or directly running Application.java). Any changes to controllers or HTML files will now be reflected immediately upon browser refresh.