Spring Boot Template Engine Hot Deployment Techniques

In Spring Boot, template engines such as Thymeleaf, FreeMarker, Groovy, and Velocity cache pages by default, so changes are not reflected after a refresh; disabling the cache in application.properties solves this.

1. Disable cache via properties: Thymeleaf: spring.thymeleaf.cache=false FreeMarker: spring.freemarker.cache=false Groovy: spring.groovy.template.cache=false Velocity: spring.velocity.cache=false

2. Debug mode hot deployment: Run the application in Debug mode for the simplest and fastest hot‑reload, though it cannot handle changes to configuration files, method names, or added classes.

3. spring‑boot‑devtools: Adding the spring-boot-devtools dependency enables automatic restart and live reload for both templates and code. Example dependency:

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

This approach covers all changes, including configuration files, but restarts the application on file changes, which may affect experience.

4. Spring Loaded: Similar to Debug mode but works without starting the JVM in Debug; it requires adding the Spring Loaded agent to the run configuration.

5. JRebel: A commercial Java hot‑deployment tool that offers extensive support for Spring Boot; it provides a 14‑day trial and can be installed via plugin.

Additional links at the end point to related technical articles and a large collection of interview questions covering many backend technologies.