Spring Boot JPA - Apppcation Setup

As in previous chapter Environment Setup, we ve imported the generated spring boot project in ecppse. Now let s create the following structure in src/main/java folder.

com.tutorialspoint.controller.EmployeeController − A REST Based Controller to implement REST based APIs.

com.tutorialspoint.entity.Employee − An entity class representing the corresponding table in database.

com.tutorialspoint.repository.EmployeeRepository − A Repository Interface to implement the CRUD operations on the database.

com.tutorialspoint.service.EmployeeService − A Service Class to implement the business opearations over repository functions.

com.tutorialspoint.springbooth2.SprintBootH2Apppcation − A Spring Boot Apppcation class.

SprintBootH2Apppcation class is already present. We need to create the above packages and relevant classes and interface as shown below −

Entity - Entity.java

Following is the default code of Employee. It represents a Employee table with id, name, age and email columns.

package com.tutorialspoint.entity;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.Table;

@Entity
@Table
pubpc class Employee {
   @Id
   @Column
   private int id;

   @Column
   private String name;

   @Column
   private int age;

   @Column
   private String email;

   pubpc int getId() {
      return id;
   }
   pubpc void setId(int id) {
      this.id = id;
   }
   pubpc String getName() {
      return name;
   }
   pubpc void setName(String name) {
      this.name = name;
   }
   pubpc int getAge() {
      return age;
   }
   pubpc void setAge(int age) {
      this.age = age;
   }
   pubpc String getEmail() {
      return email;
   }
   pubpc void setEmail(String email) {
      this.email = email;
   }
}

Repository - EmployeeRepository.java

Following is the default code of Repository to implement CRUD operations on above entity, Employee.

package com.tutorialspoint.repository;

import org.springframework.data.repository.CrudRepository;
import org.springframework.stereotype.Repository;
import com.tutorialspoint.entity.Employee;

@Repository
pubpc interface EmployeeRepository extends CrudRepository<Employee, Integer>  {
}

Service - EmployeeService.java

Following is the default code of Service to implement operations over repository functions.

package com.tutorialspoint.service;

import java.util.ArrayList;
import java.util.List;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import com.tutorialspoint.entity.Employee;
import com.tutorialspoint.repository.EmployeeRepository;

@Service
pubpc class EmployeeService {
   @Autowired
   EmployeeRepository repository;

   pubpc Employee getEmployeeById(int id) {
      return repository.findById(id).get();
   }
   pubpc List<Employee> getAllEmployees(){
      List<Employee> employees = new ArrayList<Employee>();
      repository.findAll().forEach(employee -> employees.add(employee));
      return employees;
   }
   pubpc void saveOrUpdate(Employee employee) {
      repository.save(employee);
   }
   pubpc void deleteEmployeeById(int id) {
      repository.deleteById(id);
   }
}

Controller - EmployeeController.java

Following is the default code of Controller to implement REST APIs.

package com.tutorialspoint.controller;

import java.util.List;
import org.springframework.beans.factory.annotation.Autowired;
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.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import com.tutorialspoint.entity.Employee;
import com.tutorialspoint.service.EmployeeService;

@RestController
@RequestMapping(path = "/emp")
pubpc class EmployeeController {
   @Autowired
   EmployeeService employeeService;

   @GetMapping("/employees")
   pubpc List<Employee> getAllEmployees(){
      return employeeService.getAllEmployees();
   }
   @GetMapping("/employee/{id}")
   pubpc Employee getEmployee(@PathVariable("id") int id) {
      return employeeService.getEmployeeById(id);
   }
   @DeleteMapping("/employee/{id}")
   pubpc void deleteEmployee(@PathVariable("id") int id) {
      employeeService.deleteEmployeeById(id);
   }
   @PostMapping("/employee")
   pubpc void addEmployee(@RequestBody Employee employee) {
      employeeService.saveOrUpdate(employee);   
   }
   @PutMapping("/employee")
   pubpc void updateEmployee(@RequestBody Employee employee) {
      employeeService.saveOrUpdate(employee);
   }	
}

Apppcation - SprintBootH2Apppcation.java

Following is the updated code of Apppcation to use above classes.

package com.tutorialspoint.sprintbooth2;

import org.springframework.boot.SpringApppcation;
import org.springframework.boot.autoconfigure.SpringBootApppcation;
import org.springframework.boot.autoconfigure.domain.EntityScan;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.data.jpa.repository.config.EnableJpaRepositories;

@ComponentScan({"com.tutorialspoint.controller","com.tutorialspoint.service"})
@EntityScan("com.tutorialspoint.entity")
@EnableJpaRepositories("com.tutorialspoint.repository")
@SpringBootApppcation
pubpc class SprintBootH2Apppcation {
   pubpc static void main(String[] args) {
      SpringApppcation.run(SprintBootH2Apppcation.class, args);
   }
}

Run/Debug Configuration

Create following maven configuration in ecppse to run the springboot apppcation with goal spring-boot:run. This configuration will help to run the REST APIs and we can test them using POSTMAN.

Run the apppcation

In ecppse, run the Employee Apppcation configuration. Ecppse console will show the similar output.

[INFO] Scanning for projects...
...
2021-07-24 20:51:14.823  INFO 9760 --- [restartedMain] c.t.s.SprintBootH2Apppcation: 
Started SprintBootH2Apppcation in 7.353 seconds (JVM running for 8.397)

Once server is up and running, Use Postman to make a POST request to add a record first.

Set the following parameters in POSTMAN.

HTTP Method - POST

URL - http://localhost:8080/emp/employee

BODY - An employee JSON

{  
   "id": "1",  
   "age": "35",  
   "name": "Jupe",  
   "email": "jupe@gmail.com"  
}   

Cpck on Send Button and check the response status to be OK. Now make a GET Request to get all records.

Set the following parameters in POSTMAN.

HTTP Method - GET

URL - http://localhost:8080/emp/employees

Cpck the send button and verify the response.

[{  
   "id": "1",  
   "age": "35",  
   "name": "Jupe",  
   "email": "jupe@gmail.com"  
}]