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Jotty John
Jotty John

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Write your first Spring Boot application

#springboot #microservices #restapi

Creating a Spring Boot application involves several steps. Below is a guide to help you get started with a simple Spring Boot application:

Prerequisites
Java Development Kit (JDK): Ensure you have JDK 8 or later installed.
IDE: An Integrated Development Environment like IntelliJ IDEA, Eclipse, or VSCode.
Maven/Gradle: Build tools for managing project dependencies.

Step-by-Step Guide

1. Set Up Your Project
You can set up your project using Spring Initializr or manually.

Using Spring Initializr:

  • Go to Spring Initializr.

  • Select the following options:

    1. Project: Maven Project
    2. Language: Java
    3. Spring Boot: Latest stable version
    4. Project Metadata: Fill in Group, Artifact, and other details.
    5. Dependencies: Add dependencies like Spring Web, Spring Data
    JPA, H2 Database, etc.

  • Click on Generate to download the project as a zip file.

  • Unzip the file and open it in your IDE.

Manually:

  • Create a directory for your project.
  • Create a pom.xml file (for Maven) or build.gradle file (for Gradle).
  • Add the necessary Spring Boot dependencies.

Example pom.xml for Maven:

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion> <groupId>com.demo</groupId> <artifactId>demo</artifactId> <version>0.0.1-SNAPSHOT</version> <packaging>jar</packaging> <parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>3.0.0</version> <relativePath/> <!-- lookup parent from repository --> </parent> <dependencies> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-data-jpa</artifactId> </dependency> <dependency> <groupId>com.h2database</groupId> <artifactId>h2</artifactId> <scope>runtime</scope> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-test</artifactId> <scope>test</scope> </dependency> </dependencies> <build> <plugins> <plugin> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-maven-plugin</artifactId> </plugin> </plugins> </build> </project>
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2. Create the Main Application Class
Create a main class annotated with @SpringBootApplication. This class will serve as the entry point for your application.

package com.demo.app; import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication; @SpringBootApplication public class SpringBootApp{ public static void main(String[] args) { SpringApplication.run(SpringBootApp.class, args); } }
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3. Create a REST Controller
Create a simple REST controller to handle HTTP requests.

package com.demo.controller; 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!"; } }
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4. Configure Your Application
Configure your application properties. Open src/main/resources/application.properties and add any necessary configurations.

For example, to configure the H2 database:

spring.datasource.url=jdbc:h2:mem:testdb spring.datasource.driverClassName=org.h2.Driver spring.datasource.username=sa spring.datasource.password=password spring.h2.console.enabled=true spring.jpa.database-platform=org.hibernate.dialect.H2Dialect
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5. Run Your Application
You can run your application in several ways:

  • Using your IDE's run configuration.
  • Running the main method in DemoApplication.
  • Using Maven from the command line: mvn spring-boot:run.

6. Access Your Application
Once the application is running, you can access the REST endpoint in your browser or via curl/Postman:

http://localhost:8080/hello

Additional Features
Database Interaction: You can create entities and repositories to interact with a database.
Service Layer: Add services to handle business logic.
Exception Handling: Implement global exception handling using @ControllerAdvice.

Example of Adding a JPA Entity

package com.demo.model; import javax.persistence.Entity; import javax.persistence.GeneratedValue; import javax.persistence.GenerationType; import javax.persistence.Id; @Entity public class User { @Id @GeneratedValue(strategy = GenerationType.AUTO) private Long id; private String name; // getters and setters }
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Example of a Repository

package com.demo.repo; import org.springframework.data.repository.CrudRepository; public interface UserRepository extends CrudRepository<User, Long> { }
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Example of a Service

package com.demo.service; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.stereotype.Service; import java.util.Optional; @Service public class UserService { @Autowired private UserRepository userRepository; public Iterable<User> getAllUsers() { return userRepository.findAll(); } public Optional<User> getUserById(Long id) { return userRepository.findById(id); } public User saveUser(User user) { return userRepository.save(user); } public void deleteUser(Long id) { userRepository.deleteById(id); } }
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Example of a Controller Using the Service

package com.demo.controller; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.web.bind.annotation.*; @RestController @RequestMapping("/users") public class UserController { @Autowired private UserService userService; @GetMapping public Iterable<User> getAllUsers() { return userService.getAllUsers(); } @GetMapping("/{id}") public User getUserById(@PathVariable Long id) { return userService.getUserById(id).orElseThrow(() -> new UserNotFoundException(id)); } @PostMapping public User createUser(@RequestBody User user) { return userService.saveUser(user); } @DeleteMapping("/{id}") public void deleteUser(@PathVariable Long id) { userService.deleteUser(id); } }
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By following these steps, you can create a basic Spring Boot application. You can then extend it with more features as needed.

Top comments (5)

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tantess2023 profile image
Joseph •

This post is very good for beginners! It provides a clear, step-by-step guide to setting up a Spring Boot application from scratch. The detailed explanations and examples make it easy to follow along and understand the basics. Great job!

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jottyjohn profile image
Jotty John •

Thanks!!

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irfan_rizvi_e094bcd9f1aa1 profile image
Irfan Rizvi •

I ended up in 404, error situation, and got to know that demo.app and demo.controller should be either in the same package (app) or need to use @ComponentScan(basePackages = {"com.demo.app", "com.demo.controller"}) above SpringBootApp class.

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jjkaduppil profile image
HighThinker •

Good!

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tanay_joseph_3089b98cb360 profile image
Tanay Joseph •

great