The IntelliJ IDEA Ultimate has the specific Spring Boot Run configuration which can be used when running Spring Boot applications. However, the IntelliJ IDEA CE doesn't support this feature and it needs to be configured for running Spring Boot applications as normal Java Applications.

Comparison of IntelliJ IDEA Ultimate vs IntelliJ IDEA Community can be found here.

Prerequisites:

IntelliJ IDEA CE installed, or else download from here.
JDK installed and configured locally.

The following walkthrough will explain how this can be achieved for an existing application in IntelliJ IDEA CE.

Step 1: Creating a Spring Boot application using spring.io.

Go to spring.io and generate a simple Spring project using the properties as described below.

Project: Maven Project

Spring Boot: 2.7.3

Group: com.test

Artifact: spring-test

Name: spring-test

Description: Spring test application

Package name: com.test.spring-test

Packaging: JAR

Java: 11

Dependencies:

Spring Boot DevTools
Spring Web
Thymeleaf

Click on the Generate button to download the project as a ZIP file.

Alternatively, clone the existing application available here on Github.

Step 2: Importing the application to IntelliJ IDEA CE.

First unzip the project if generated via spring.io. Open IntelliJ CE and go to File > Open and select the project.

Project should be imported to the IDE as below.

Step 3: Configuring the project to run locally.

Go to Edit Configurations > Add New > Application

In the newly opened window, select Modify Options > Add VM Options. This step will allow us to specify a local server with a port.

Add following details in the configuration window.

Name: Spring-test-application

VM Options: -Dserver.port=8080

Java: java 15

Main class: com.test.springtest.SpringTestApplication

Click on Apply and OK to save.

We should now see the new run option as below.

Click on the run button to build and run the project for the first time. The spring console output should look like below when the project is up and running successfully.

Go to localhost:8080 and it should display as below.

The Whitelabel Error is expected at this stage since we don't have a root path and a template page configured yet. We'll be adding this in the next step.

Step 4: Adding a simple controller and a Thymeleaf template page for testing.

Before adding any changes, make sure the following setting in IntelliJ is set which enables reloading the project upon new changes to the files.

Preferences > Build, Execution, Deployment > Build Tools > Reload project after changes in the build script

Then in Advanced Settings enable the following compiler setting.

Once these settings are enabled, follow the steps below to create a new controller and an associated template page.

Create a new package - com.test.springtest.controller and add new a Java class - HomeController.java to it as shown below.

Add the following code to the HomeController.java

// HomeController.java
package com.test.springtest.controller;

import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.GetMapping;

@Controller
public class HomeController {

    @GetMapping("/")
    public String displayHome(Model model) {
        model.addAttribute("message", "Thank you for visiting.");
        return "home";
    }
}

Create home.html in src/main/resources/templates

<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml" xmlns:th="http://www.thymeleaf.org">
   <head>
      <meta charset="UTF-8">
      <title>Spring Boot Thymeleaf Web Application</title>
   </head>
   <body>
      <h1>Welcome to Spring Boot Thymeleaf</h1>
      <p>
         Hey there! 
         <th:block th:text="${message}">message</th:block>
      </p>
   </body>
</html>

Save the changes and refresh localhost:8080.

The project can be found here in Github.