Spring Boot is an open-source Java-based framework designed to simplify the creation of stand-alone, production-grade Spring applications. Learn Spring Boot from scratch with this comprehensive guide, a well-liked framework for rapidly creating Spring-based apps. Explore our Spring Boot course syllabus to kickstart your learning journey.
Spring Boot Basics
Here are the breakdown of Spring Boot key aspects:
What is Spring Boot?
An addition to the Spring framework, Spring Boot makes it easier to set up and create Spring apps. It offers:
- Auto-configuration for most components.
- Embedded servers (Tomcat, Jetty, etc.).
- Features that are ready for production, such as externalized configuration, health checks, and metrics.
Salient Features of Spring Boot
The key features of Spring Boot:
- Auto Configuration: This feature sets up your Spring application automatically according to the dependencies you add. This drastically cuts down on the boilerplate code you have to write.
- Opinionated Starters: To help you get started fast, this resource offers pre-packaged dependencies for popular use cases (such as Spring Web, Spring Data JPA, and Spring Security).
- Embedded Servers: For simple deployment, incorporate servers like Tomcat, Jetty, or Undertow inside your application.
- Command Line Interface (CLI): Provides a robust CLI for managing dependencies, launching apps, and starting new projects.
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Benefits of Using Spring Boot
The advantages of using Spring Boot:
- Rapid Development: Reduces boilerplate code and offers a simplified setup to expedite development.
- Simplified Deployment: Construct a single executable JAR or WAR file out of your program.
- Enhanced Productivity: Pay more attention to business logic than infrastructure issues.
- Strong Ecosystem and Community: There is a sizable and vibrant community with a wealth of tutorials, third-party libraries, and documentation.
Key Concepts of Spring Boot
The major concepts of Spring Boot:
- Spring: A feature-rich framework for Java application development that offers aspects-oriented programming, transaction management, and dependency injection.
- Spring MVC: Developed on top of Spring, Spring MVC is a web framework that lets you develop RESTful web services and web apps.
- Spring Data JPA: By offering a higher-level abstraction, JPA (Java Persistence API) streamlines data access.
- Spring Security: It offers extensive security functionalities including authorization and authentication.
Explore our Spring Boot interview questions and answers.
Getting Started with Spring Boot
System Prerequisites:
- Java JDK 8 or higher.
- Maven or Gradle (for dependency management).
- IDE (IntelliJ IDEA, Eclipse, or VS Code).
Create a Spring Boot Project:
- Use Spring Initializr:
- Go to Spring Initializr.
- Fill in the project details:
- Project: Maven or Gradle.
- Language: Java.
- Spring Boot Version: Choose the latest stable version.
- Group: com.example (or your package name).
- Artifact: demo.
- Dependencies: Add Spring Web (for building REST APIs).
- Click Generate to download the project.
Import the Project:
- After downloading the ZIP file, extract it.
- Import it as a Gradle or Maven project into your IDE.
Project Structure
Once completed the project, when you import, it will look as below:
Fine-tune your skills with our Spring Boot Project Ideas.
Create a Simple REST API
Step 1: Create a controller.
The HelloController.java class should be created in the src/main/java/com/example/demo folder:
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, Spring Boot!”;
}
}
Step 2: Run the Application
Open DemoApplication.java (the main class).
Use the command or the “Run” button in your IDE to launch the application:
Bash Command
mvn spring-boot:run
Go to http://localhost:8080/hello in your browser. You ought to observe:
Hello, Spring Boot!
Add Custom Configuration
You can use the application.properties file to personalize your application with Spring Boot.
Example: Change Server Port
Add the following after opening src/main/resources/application.properties:
server.port=8081
Your program will now use port 8081 to operate.
Add a Service Layer
Divide business logic into a service layer in accordance with best practices.
Step 1: Create a Service
The HelloService.java class should be created:
package com.example.demo;
import org.springframework.stereotype.Service;
@Service
public class HelloService {
public String getMessage() {
return “Hello from the Service Layer!”;
}
}
Step 2: Update the Controller
To utilize the service, alter HelloController.java as follows:
package com.example.demo;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;
@RestController
public class HelloController {
@Autowired
private HelloService helloService;
@GetMapping(“/hello”)
public String sayHello() {
return helloService.getMessage();
}
}
Check for the complete Java Spring tutorial for beginners here.
Add Database Support (Optional)
Using Spring Data JPA to integrate with databases is made simple by Spring Boot.
Step 1: Add Dependencies
In pom.xml, add:
<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>
Step 2: Configure the Database
Add the following to application.properties:
spring.datasource.url=jdbc:h2:mem:testdb
spring.datasource.driverClassName=org.h2.Driver
spring.datasource.username=sa
spring.datasource.password=password
spring.jpa.database-platform=org.hibernate.dialect.H2Dialect
spring.h2.console.enabled=true
Step 3: Create an Entity and Repository
Create a User.java entity class:
package com.example.demo;
import jakarta.persistence.Entity;
import jakarta.persistence.GeneratedValue;
import jakarta.persistence.GenerationType;
import jakarta.persistence.Id;
@Entity
public class User {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
private String name;
// Getters and Setters
}
Create a UserRepository.java repository interface:
package com.example.demo;
import org.springframework.data.jpa.repository.JpaRepository;
public interface UserRepository extends JpaRepository<User, Long> {
}
Step 4: Utilize a Service’s Repository
To utilize the repository, update HelloService.java:
package com.example.demo;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import java.util.List;
@Service
public class HelloService {
@Autowired
private UserRepository userRepository;
public String getMessage() {
User user = new User();
user.setName(“Kenneth”);
userRepository.save(user);
List<User> users = userRepository.findAll();
return “Hello, ” + users.get(0).getName() + “!”;
}
}
Explore challenges and solutions for the Spring Boot developers.
Test the Application
Run the program, then go to http://localhost:8081/hello.
Output:
Hello, Kenneth!
Conclusion
The fundamentals of Spring Boot are covered in this tutorial. Now, you can interact with databases, add a service layer, and create REST APIs. Learn Spring Boot from scratch. Have fun with your coding! For more expertise, enroll in our Spring Boot training in Chennai.
