Spring Data JPA

Spring Data JPA is a framework, originally developed by a Spring Pivotal team and runs top of the hibernate. In another word Spring data JPA is an implementation of Java Persistence API. Makes it easy to easily implement JPA based repositories.

JPA

JPA is a short term of Java Persistence API. It is just a specification that facilitates object relational mapping to manage relational data in Java applications, It is one of the advance feature in Java. It helps to convert the Java POJO object into table data and table data into Java POJO objects. And do not need to write a SQL statement. JPA will take care of SQL query generation based on entity class that we are working on. But we can not directly use the JPA because its just a specification, so we need ORM framework.

ORM Framework

ORM is short term of Object Relational Mapping. And it is a functionality which is used to develop and maintain the relationship between an object and relational database and relational database to object. There are many ORM frameworks in the market. Those all implementations of JPA.

Hibernate
Spring Data JPA
TopLink
ORMLite
iBATIS
JPOX

Spring Data JPA Features

Sophisticated support to build repositories based on Spring and JPA
Support for Querydsl predicates and thus type-safe JPA queries
Transparent auditing of domain class
Pagination support, dynamic query execution, ability to integrate custom data access code
Validation of @Query annotated queries at bootstrap time
Support for XML based entity mapping
JavaConfig based repository configuration by introducing @EnableJpaRepositories

pom.xml

<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-data-jpa</artifactId>
		</dependency>
		
		<dependency>
			<groupId>mysql</groupId>
			<artifactId>mysql-connector-java</artifactId>
			<scope>runtime</scope>
		</dependency>

application.properties


spring.datasource.url=jdbc:mysql://localhost:3306/samplecoder
spring.datasource.username=root
spring.datasource.password=root

spring.jpa.hibernate.ddl-auto=update

spring.jackson.serialization.order-map-entries-by-keys=true
spring.jackson.serialization.FAIL_ON_EMPTY_BEANS=false

Entity Class

package com.samplecoder.emo.entity;

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;

@Entity
public class Student {
	@Id
	@GeneratedValue(strategy = GenerationType.IDENTITY)
	private int id;
	private String name;
	private int std;
	public int getId() {
		return id;
	}
	public void setId(int id) {
		this.id = id;
	}
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public int getStd() {
		return std;
	}
	public void setStd(int std) {
		this.std = std;
	}
}

Repository class

package com.samplecoder.emo.repository;

import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.stereotype.Repository;

import com.samplecoder.emo.entity.Student;

@Repository
public interface StudentRepository extends JpaRepository<Student, Integer>{

}

Rest Controller

package com.samplecoder.emo.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.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;

import com.samplecoder.emo.entity.Student;
import com.samplecoder.emo.repository.StudentRepository;

@RestController
@RequestMapping("/api/student")
public class StudentController {
	
	@Autowired
	private StudentRepository studentRepository;
	
	@PostMapping("/save")
	private Student save(@RequestBody Student student) {
		student = studentRepository.save(student);
		return student;
	}
	
	@DeleteMapping("/delete/{id}")
	private ResponseEntity<String> delete(@PathVariable("id") Integer id){
		studentRepository.deleteById(id);
		return new ResponseEntity<String>("DELTETED", HttpStatus.OK);
	}
	
	@GetMapping("/get/{id}")
	private Student get(@PathVariable(name = "id", required = true) Integer id) {
		return studentRepository.getById(id);
	}
	
	@GetMapping("/list")
	private List<Student> list(){
		return studentRepository.findAll();
	}
}

Test Result

//Create
Request: http://localhost:8080/api/student/save
Body:
{
	"name":"Muthu",
	"std":10
}
Response:
{
	"id":1,
	"name":"Muthu",
	"std":10
}

//Update
Request: http://localhost:8080/api/student/save
Body:
{
	"id":1,
	"name":"Muthu",
	"std":12
}
Response:
{
	"id":1,
	"name":"Muthu",
	"std":12
}

//Get By ID
Request: http://localhost:8080/api/student/get/1
Response:
{
    "id": 1,
    "name": "Muthu",
    "std": 12,
    "hibernateLazyInitializer": {}
}

//List All
Request: http://localhost:8080/api/student/list
Response:
[
    {
        "id": 1,
        "name": "Muthu",
        "std": 12
    }
]

//Delete
Request: http://localhost:8080/api/student/delete/1
Response: DELTETED

JPA

ORM Framework

Spring Data JPA Features

Entity Class

Repository class

Rest Controller

Test Result

About MNP Muthu

One Comment on “Spring Data JPA”

JPA

ORM Framework

Spring Data JPA Features

Entity Class

Repository class

Rest Controller

Test Result

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About MNP Muthu

One Comment on “Spring Data JPA”