Spring Initializer – using Java and Maven

Spring Initializr is a web tool which is provided by Spring on official site https://start.spring.io/ We can create Spring Boot project by providing project details.

In the below example, we added the springboot-starter-web dependency to write REST Endpoints.

After providing the Group, Artifact, Dependencies, Build Project, Platform and Version, click Generate Project button. The zip file will get downloaded and the files will be extracted. After the project is downloaded, unzip the file.

The maven file pom.xml will have the Web dependency we had selected above.

Note that only the Spring boot starter parent has a version number. Spring boot starter web doesn’t have a version as it is automatically configured based on version of the parent.

You can find the main class file under src/java/main directories with the default package.

To write a simple Hello World Rest Endpoint in the Spring Boot Application main class file itself, follow the steps shown below:

• Firstly, add the @RestController annotation at the top of the class.
• Now, write a Request URI method with @RequestMapping annotation.
• Then, the Request URI method should return the Hello World string.

Create an executable JAR by executing the below Maven command in the folder having pom.xml
C:\Users\SaravananP\Downloads\demo\mvn clean install

The .jar file will be created in the target folder as indicated above

Run the Jar file using java –jar and verify the results

Application Properties

In the above examples, we have seen that Spring boot automatically configured Tomcat to run in port 8080. We can override this by specifying the port in the file src\main\resources\application.properties

If we rebuild the jar and execute it, we will get an error in http://localhost:8080 and be able to see the Hello World message in http://localhost:9090