Spring Boot, H2, JPA, Hibernate Restful CRUD API Tutorial

In this tutorial, I'm gonna show you how to build a CRUD rest APIs using Spring boot, spring data JPA, Hibernate and H2 database.
Learn Spring boot at https://www.javaguides.net/p/spring-boot-tutorial.html
Learn Hibernate at https://www.javaguides.net/p/hibernate-tutorial.html
We’ll first build the APIs to create, retrieve, update and delete a Product, and then test them using postman.

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 setup a project with almost zero configuration and start building the things that actually matter to your application.

High-Level Architecture

Tools and technologies used

  • Spring Boot - 2.1.0.RELEASE
  • JDK - 1.8 or later
  • Spring Framework - 5.1.2 RELEASE
  • Hibernate - 5.2.17. Final
  • JPA
  • Maven - 3.2+
  • IDE - Eclipse or Spring Tool Suite (STS)
  • H2 Embedded Database

The pom.xml File

<?xml version="1.0" encoding="UTF-8"?>
<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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
 <modelVersion>4.0.0</modelVersion>
 <parent>
     <groupId>org.springframework.boot</groupId>
     <artifactId>spring-boot-starter-parent</artifactId>
     <version>2.1.0.RELEASE</version>
     <relativePath/> <!-- lookup parent from repository -->
 </parent>
 <groupId>net.javaguides.springboot</groupId>
 <artifactId>springboot-crud-hibernate-example</artifactId>
 <version>0.0.1-SNAPSHOT</version>
 <name>springboot-crud-hibernate-example</name>
 <description>spring boot crud operations example with hibernate</description>

 <properties>
     <java.version>1.8</java.version>
 </properties>

 <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>
 </dependencies>

 <build>
     <plugins>
         <plugin>
             <groupId>org.springframework.boot</groupId>
             <artifactId>spring-boot-maven-plugin</artifactId>
          </plugin>
     </plugins>
 </build>
</project>
  • spring-boot-starter-web: It is used for building a web layer, including REST APIs, applications using Spring MVC. Uses Tomcat as the default embedded container.
  • spring-boot-starter-data-jpa: It includes spring data, hibernate, HikariCP, JPA API, JPA Implementation (default is hibernate), JDBC and other required libraries.
  • h2: Though we can add any database easily using data source properties in the application.properties file, we are using the h2 database to reducing unnecessary complexity.

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
By design, the in-memory database is volatile and data will be lost when we restart the application.
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 javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Table;

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> {

}

Service Layer (uses repository)

The service layer is optional – still recommended to perform additional business logic if any. Generally, we will connect with 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

Finally, expose all operations through MVC URLs or REST endpoints. Clients will connect with these endpoints to create/get/update/delete product records.
Notice the usage of annotations @RestController, @RequestMapping, @GetMapping, @PostMapping, and @DeleteMapping to map various URIs to controller methods.
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;
    }
}

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);
    }
}

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);
    }
}

Test Rest API using Postman Client

The below video tutorial covers testing rest APIs using postman client:

Download source code

The source code of this tutorial available on my GitHub Repository.


Comments

  1. why do you use ResponseEntity and HttpStatus? and what's their role within the controller?

    ReplyDelete

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