Run Spring Boot Maven Project in IntelliJ

IntelliJ IDEA is a popular IDE for Java development, and it provides excellent support for Spring Boot projects. In this tutorial, we will walk you through the steps to create, import, and run a Spring Boot Maven project in IntelliJ IDEA.

Prerequisites

• JDK 17 or later
• Maven
• IntelliJ IDEA installed on your machine (Community or Ultimate edition)
• Spring Boot (version 3.2+ recommended)

Step 1: Set Up a Spring Boot Project Using Spring Initializr

Use Spring Initializr to generate a new Spring Boot project with the following configuration:

• Project: Maven Project
• Language: Java
• Spring Boot: 3.2.x
• Dependencies: Spring Web

Download the generated project, unzip it, and open it in IntelliJ IDEA.

Example Project Structure

The basic structure of a Spring Boot project with Maven looks like this:

my-spring-boot-app/
├── src/
│   ├── main/
│   │   ├── java/
│   │   │   └── com/example/demo/
│   │   │       └── DemoApplication.java
│   │   └── resources/
│   │       └── application.properties
│   └── test/
│       └── java/
│           └── com/example/demo/
│               └── DemoApplicationTests.java
├── mvnw
├── mvnw.cmd
├── pom.xml
└── .mvn/
    └── wrapper/
        └── maven-wrapper.properties

Step 2: Import the Maven Project into IntelliJ IDEA

1. Open IntelliJ IDEA: Launch IntelliJ IDEA on your machine.

2. Import Project:

   • Click on File -> New -> Project from Existing Sources.
   • Navigate to the root directory of your Spring Boot project and select the pom.xml file.
   • Click OK.

3. Import Maven Projects:

   • IntelliJ IDEA will detect that it is a Maven project and open the "Import Project from Maven" dialog.
   • Ensure that the Import Maven projects automatically option is checked.
   • Click Next and then Finish.

IntelliJ IDEA will import the project and resolve all dependencies specified in the pom.xml file.

Step 3: Explore the Project Structure

After the project is imported, you can explore the project structure in the Project Explorer panel on the left side of the IntelliJ IDEA window. You should see the standard Maven project layout with src/main/java, src/main/resources, src/test/java, and src/test/resources directories.

Step 4: Application Class

Let's understand the Spring boot Main Java class named DemoApplication in the src/main/java/com/example/demo directory.

package com.example.demo;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class DemoApplication {

    public static void main(String[] args) {
        SpringApplication.run(DemoApplication.class, args);
    }
}

Explanation:

• @SpringBootApplication: Marks this class as the main entry point for the Spring Boot application.
• main method: Starts the Spring Boot application.

Step 5: Create a Simple REST Controller

To verify the application works as expected, let's create a simple REST controller.

Create a Java class named HelloController in the src/main/java/com/example/demo directory:

package com.example.demo;

import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class HelloController {

    @GetMapping("/hello")
    public String sayHello() {
        return "Hello, World!";
    }
}

Explanation:

• @RestController: Marks this class as a REST controller.
• @GetMapping("/hello"): Maps HTTP GET requests to the /hello endpoint to the sayHello method.
• sayHello method: Returns a "Hello, World!" message.

Step 6: Run the Application

Using IntelliJ IDEA

1. Run the Application:

   • Right-click on the DemoApplication class in the Project Explorer.
   • Select Run 'DemoApplication.main()'.

   IntelliJ IDEA will build the project and start the Spring Boot application.

2. View the Output:

   • The Run window will open at the bottom of the IntelliJ IDEA window.
   • You should see logs indicating that the application has started successfully.

Verifying the Application

Open a web browser or a tool like Postman and navigate to the following URL to verify the application:

• Hello Endpoint:
  • URL: http://localhost:8080/hello
  • Method: GET
  • Response: Hello, World!

You should see the "Hello, World!" message returned by the HelloController.

Step 7: Creating a Test Class

Create a Java class named DemoApplicationTests in the src/test/java/com/example/demo directory.

package com.example.demo;

import org.junit.jupiter.api.Test;
import org.springframework.boot.test.context.SpringBootTest;

@SpringBootTest
class DemoApplicationTests {

    @Test
    void contextLoads() {
    }
}

Explanation:

• @SpringBootTest: Indicates that this is a Spring Boot test.
• contextLoads method: Tests if the Spring application context loads successfully.

Running Tests

1. Run Tests:

   • Right-click on the DemoApplicationTests class in the Project Explorer.
   • Select Run 'DemoApplicationTests'.

2. View Test Results:

   • The Run window will open at the bottom of the IntelliJ IDEA window.
   • You should see the test results indicating that the tests passed successfully.

Conclusion

In this tutorial, you have learned how to create, import, and run a Spring Boot Maven project in IntelliJ IDEA. We covered:

• Setting up a Spring Boot project using Spring Initializr with Maven.
• Importing the Maven project into IntelliJ IDEA.
• Creating the main application class.
• Creating a simple REST controller to verify the application works as expected.
• Running the application using IntelliJ IDEA.
• Creating and running tests.

By following these steps, you can easily set up and manage Spring Boot projects using Maven in IntelliJ IDEA, leveraging its powerful development and debugging features.