How to hot deploy Spring MVC - Spring Boot Application in Intelij

• Create your first Spring MVC / Spring Boot application by cloning the    sample project provided in Spring's web site 

•  In IntelliJ open the Maven project

• mvn clean install 

• Right click the Application.java class and simply run it in Intellij.

• Notice that once you access the application from http://localhost:8080/greeting  and if you do any changes  to the files in src/main/java/resources/templates/greeting.html; those changes do not get reflected unless you do a restart.

• However if you create a webapp folder and have an index.jsp under i.e. src/main/webapp/index.jsp  and make changes to that file; then  you will be able to dynamically see any changes done to it with a simple page refresh in the browser. Note: Its simply the files under src/main/java/resources/ that do not reflect changes. To overcome this, and to achieve class level and resource level changes to hot deploy ..

• We are going to add the springloaded plugin. Add the plugin dependency as follows:
  

  <plugin>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-maven-plugin</artifactId>
  <dependencies>
  

  <dependency>

  <groupId>org.springframework</groupId>

  <artifactId>springloaded</artifactId>

  <version>1.2.0.RELEASE</version>

  </dependency>

  </dependencies>
  </plugin>

• Do a mvn clean install and make sure the jar is downloaded to your m2 repository.

•  Next copy the downloaded jar file from the repository to your  root folder of your application.

• In Intelij -> Run configuration -> Specify VM arguments :

       -Djavaagent:springloaded-1.2.0.RELEASE.jar -noverify
       
        note: you can also give the path like c:\\myfolder\\springloaded.jar
       so it will be like
       -Djavaagent:c:\\myfolder\\springloaded.jar -noverify.

•  inside src/main/java/resources folder create a new file application.properties.    Its contents should have two properties :

spring.template.cache=false
spring.thymeleaf.cache=false
 

• shut down the servers and run the application again. Do class level changes and make changes to the /java/resources/templates/greeting.html . After doing the changes make sure to run MAKE to compile the classes.

• Changes will be reflected immediately in the browser without having to rerun the Application.java.