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Learn Spring boot at https://www.javaguides.net/p/spring-boot-tutorial.html
Learn Hibernate at https://www.javaguides.net/p/hibernate-tutorial.html
Spring Boot has taken the Spring framework to the next level. It has drastically reduced the configuration and setup time required for spring projects.
You can set up a project with almost zero configuration and start building the things that actually matter to your application.
High-Level Architecture
Add Maven Dependencies
<dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-data-jpa</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</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>
Configure H2 Database
By default, Spring Boot configures the application to connect to an in-memory store with the username sa and an empty password. However, we can change those parameters by adding the following properties to the application.properties file: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
We can change that behavior by using file-based storage. To do this we need to update the spring.datasource.url:
spring.datasource.url=jdbc:h2:file:/data/demo
In this example, we will use a default configuration of the H2 database (we don't use the above configuration, the above configuration is just to know more about H2 database configuration with Spring boot). Create JPA Entity - Product.java
package net.javaguides.springboot.model;
import java.math.BigDecimal;
import java.util.Date;
import jakarta.persistence.*;
import org.hibernate.annotations.CreationTimestamp;
@Entity
@Table(name = "products")
public class Product {
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private long id;
@Column(name = "name")
private String name;
@Column(name = "description")
private String description;
@Column(name = "price")
private BigDecimal price;
@CreationTimestamp
private Date createdAt;
@CreationTimestamp
private Date updatedAt;
public long getId() {
return id;
}
public void setId(long id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getDescription() {
return description;
}
public void setDescription(String description) {
this.description = description;
}
public BigDecimal getPrice() {
return price;
}
public void setPrice(BigDecimal price) {
this.price = price;
}
public Date getCreatedAt() {
return createdAt;
}
public void setCreatedAt(Date createdAt) {
this.createdAt = createdAt;
}
public Date getUpdatedAt() {
return updatedAt;
}
public void setUpdatedAt(Date updatedAt) {
this.updatedAt = updatedAt;
}
}
Create a Spring Data Repository - ProductRepository.java
package net.javaguides.springboot.repository;
import org.springframework.data.jpa.repository.JpaRepository;
import net.javaguides.springboot.model.Product;
public interface ProductRepository extends JpaRepository<Product, Long> {
}
Create Custom Exception - ResourceNotFoundException.java
package net.javaguides.springboot.exception;
import org.springframework.web.bind.annotation.ResponseStatus;
@ResponseStatus
public class ResourceNotFoundException extends RuntimeException {
private static final long serialVersionUID = 1 L;
public ResourceNotFoundException(String message) {
super(message);
}
public ResourceNotFoundException(String message, Throwable throwable) {
super(message, throwable);
}
}
package net.javaguides.springboot.exception;
import org.springframework.web.bind.annotation.ResponseStatus;
@ResponseStatus
public class ResourceNotFoundException extends RuntimeException {
private static final long serialVersionUID = 1 L;
public ResourceNotFoundException(String message) {
super(message);
}
public ResourceNotFoundException(String message, Throwable throwable) {
super(message, throwable);
}
}
Service Layer (uses repository)
The service layer is optional – still recommended to perform additional business logic if any. Generally, we will connect with the repository here for crud operations.ProductService.java
package net.javaguides.springboot.service;
import java.util.List;
import net.javaguides.springboot.model.Product;
public interface ProductService {
Product createProduct(Product product);
Product updateProduct(Product product);
List < Product > getAllProduct();
Product getProductById(long productId);
void deleteProduct(long id);
}
ProductServiceImpl.java
package net.javaguides.springboot.service;
import java.util.List;
import java.util.Optional;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;
import net.javaguides.springboot.exception.ResourceNotFoundException;
import net.javaguides.springboot.model.Product;
import net.javaguides.springboot.repository.ProductRepository;
@Service
@Transactional
public class ProductServiceImpl implements ProductService {
@Autowired
private ProductRepository productRepository;
@Override
public Product createProduct(Product product) {
return productRepository.save(product);
}
@Override
public Product updateProduct(Product product) {
Optional < Product > productDb = this.productRepository.findById(product.getId());
if (productDb.isPresent()) {
Product productUpdate = productDb.get();
productUpdate.setId(product.getId());
productUpdate.setName(product.getName());
productUpdate.setDescription(product.getDescription());
productRepository.save(productUpdate);
return productUpdate;
} else {
throw new ResourceNotFoundException("Record not found with id : " + product.getId());
}
}
@Override
public List < Product > getAllProduct() {
return this.productRepository.findAll();
}
@Override
public Product getProductById(long productId) {
Optional < Product > productDb = this.productRepository.findById(productId);
if (productDb.isPresent()) {
return productDb.get();
} else {
throw new ResourceNotFoundException("Record not found with id : " + productId);
}
}
@Override
public void deleteProduct(long productId) {
Optional < Product > productDb = this.productRepository.findById(productId);
if (productDb.isPresent()) {
this.productRepository.delete(productDb.get());
} else {
throw new ResourceNotFoundException("Record not found with id : " + productId);
}
}
}
Spring REST Controller - ProductController
Let's create a CRUD REST API for the Product resource:package net.javaguides.springboot.controller;
import java.util.List;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.DeleteMapping;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.PutMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RestController;
import net.javaguides.springboot.model.Product;
import net.javaguides.springboot.service.ProductService;
@RestController
public class ProductController {
@Autowired
private ProductService productService;
@GetMapping("/products")
public ResponseEntity < List < Product >> getAllProduct() {
return ResponseEntity.ok().body(productService.getAllProduct());
}
@GetMapping("/products/{id}")
public ResponseEntity < Product > getProductById(@PathVariable long id) {
return ResponseEntity.ok().body(productService.getProductById(id));
}
@PostMapping("/products")
public ResponseEntity < Product > createProduct(@RequestBody Product product) {
return ResponseEntity.ok().body(this.productService.createProduct(product));
}
@PutMapping("/products/{id}")
public ResponseEntity < Product > updateProduct(@PathVariable long id, @RequestBody Product product) {
product.setId(id);
return ResponseEntity.ok().body(this.productService.updateProduct(product));
}
@DeleteMapping("/products/{id}")
public HttpStatus deleteProduct(@PathVariable long id) {
this.productService.deleteProduct(id);
return HttpStatus.OK;
}
}
The ProductController is using the ProductService to perform operations on products. We're injecting this service into the controller using the @Autowired annotation.
Each endpoint is mapped to an HTTP method using the @GetMapping, @PostMapping, @PutMapping, or @DeleteMapping annotations. The @RequestBody annotation indicates that the incoming data is expected to be in JSON format.
Running Spring Boot Application
This spring boot application has an entry point Java class called SpringbootCrudHibernateExampleApplication.java with the public static void main(String[] args) method, which you can run to start the application.package net.javaguides.springboot;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
@SpringBootApplication
public class SpringbootCrudHibernateExampleApplication {
public static void main(String[] args) {
SpringApplication.run(SpringbootCrudHibernateExampleApplication.class, args);
}
}
Download Source Code from GitHub
The source code of this tutorial is available on my GitHub Repository.
why do you use ResponseEntity and HttpStatus? and what's their role within the controller?
ReplyDelete