Setting Up a Modern Spring Boot Web Server with REST API & Web Content (2025 Guide)

• src/main/java: Application code (MySpringBootAppApplication.java).

• src/main/resources/static: Static assets (HTML, CSS, JS).

• src/main/resources/application.properties: Configuration for the application.

• pom.xml: Maven configuration and dependency management.

Edit src/main/resources/application.properties to configure your application:

# Server configuration
server.port=8080
# Leave server.servlet.context-path unset to serve /hello and / at the root

# Logging configuration
logging.level.root=INFO
logging.level.com.example=DEBUG

# Spring devtools
spring.devtools.restart.enabled=true

For different environments, create profile-specific properties:

• application-dev.properties
• application-prod.properties

For sensitive data like API keys, use environment variables.

1. Add spring-dotenv dependency to pom.xml:

<dependency>
    <groupId>me.paulschwarz</groupId>
    <artifactId>spring-dotenv</artifactId>
    <version>4.0.0</version>
</dependency>

2. Create .env.example file:

SERVER_PORT=8080
CUSTOM_API_KEY=your-api-key-here

3. Create your actual .env file (don't commit to git):

SERVER_PORT=8080
CUSTOM_API_KEY=actual-api-key-value

4. Reference env variables in application.properties:

server.port=${SERVER_PORT:8080}
api.key=${CUSTOM_API_KEY}

Create src/main/java/com/example/myspringbootapp/HelloController.java:

package com.example.myspringbootapp;

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

@RestController
public class HelloController {
@GetMapping("/hello")
public String sayHello(
@RequestParam(defaultValue = "World") String name
) {
return String.format("Hello, %s!", name);
}
}

• Run in IntelliJ: click the green play icon next to main method

• CLI:

  ✕−+

  bash

  ./mvnw spring-boot:run
  

Visit http://localhost:8080/hello and http://localhost:8080/hello?name=Spring or use:

curl http://localhost:8080/hello
curl "http://localhost:8080/hello?name=Developer"

1. Create src/main/resources/static/index.html:

   ✕−+

   html

   <!DOCTYPE html>
   <html lang="en">
   <head><meta charset="UTF-8"><title>Static Page</title></head>
   <body>
     <h1>Welcome to My Static Page!</h1>
   </body>
   </html>
   

2. Restart app and browse to http://localhost:8080/ Spring Boot serves files in static/ automatically.

Spring Boot DevTools (spring-boot-devtools dependency) enables automatic restart when compiled files on the classpath change. To optimize:

1. For IntelliJ IDEA:

• In Preferences > Build, Execution, Deployment > Compiler, enable "Build project automatically"
• Enable advanced settings: Registry (Ctrl+Alt+Shift+/) > check "compiler.automake.allow.when.app.running"

2. For CLI:

./mvnw spring-boot:run -Dspring-boot.run.jvmArguments="-Dspring.devtools.restart.enabled=true"

After editing Java sources, run ./mvnw compile in a second terminal to update the classpath and trigger a DevTools restart.

3. To run with specific profile:

./mvnw spring-boot:run -Dspring-boot.run.profiles=dev # For Maven
# For Gradle: ./gradlew bootRun --args='--spring.profiles.active=dev'

Spring Boot automatically configures your application based on the JAR dependencies you have added. For example, if spring-boot-starter-web is on the classpath, it auto-configures Tomcat and Spring MVC.

Spring Boot "Starters" are convenient dependency descriptors that you can include in your application. For example, spring-boot-starter-data-jpa for JPA/Hibernate, spring-boot-starter-security for security.

If port 8080 is in use, change it in application.properties (e.g., server.port=8081) or via command line:

./mvnw spring-boot:run -Dspring-boot.run.arguments="--server.port=8081"

Maven Central ( central.sonatype.com) is the primary public repository for Java libraries (dependencies). Spring Boot dependencies are typically fetched from here or other configured repositories (like Spring Milestones/Snapshots).

java -jar target/*.jar --spring.profiles.active=prod

When running in production, set environment variables externally:

export SERVER_PORT=80
export CUSTOM_API_KEY=production-key
java -jar target/*.jar

1. Create Dockerfile:

FROM eclipse-temurin:21-jre
WORKDIR /app
COPY target/*.jar app.jar
EXPOSE 8080
ENTRYPOINT ["java", "-jar", "app.jar"]

2. Build and run:

docker build -t myspringbootapp .
docker run -p 8080:8080 --env-file .env myspringbootapp