<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>org.springframework.boot</groupId>

            <artifactId>spring-boot-devtools</artifactId>

            <scope>runtime</scope>

            <optional>true</optional>

        </dependency>

        <dependency>

            <groupId>mysql</groupId>

            <artifactId>mysql-connector-java</artifactId>

            <scope>runtime</scope>

        </dependency>

        <dependency>

            <groupId>org.springframework.boot</groupId>

            <artifactId>spring-boot-starter-test</artifactId>

            <scope>test</scope>

        </dependency>

    </dependencies>

spring.datasource.url=jdbc:mysql://localhost:3306/employee_directory?useSSL=false

spring.datasource.username=root

spring.datasource.password=admin

package com.luv2code.springboot.cruddemo.entity;

import javax.persistence.*;

@Entity

@Table(name = "employee")

public class Employee {

    // define fields

    @Id

    @GeneratedValue(strategy=GenerationType.IDENTITY)

    @Column(name="id")

    private int id;

    @Column(name="first_name")

    private String firstName;

    @Column(name="last_name")

    private String lastName;

    @Column(name="email")

    private String email;

    public Employee () {

    }

    public Employee(String firstName, String lastName, String email) {

        this.firstName = firstName;

        this.lastName = lastName;

        this.email = email;

    }

    // define getter/setter

    public int getId() {

        return id;

    }

    public void setId(int id) {

        this.id = id;

    }

    public java.lang.String getFirstName() {

        return firstName;

    }

    public void setFirstName(java.lang.String firstName) {

        this.firstName = firstName;

    }

    public java.lang.String getLastName() {

        return lastName;

    }

    public void setLastName(java.lang.String lastName) {

        this.lastName = lastName;

    }

    public java.lang.String getEmail() {

        return email;

    }

    public void setEmail(java.lang.String email) {

        this.email = email;

    }

    // define tostring

    @Override

    public String toString() {

        return "Employee{" +

                "id=" + id +

                ", firstName=" + firstName +

                ", lastName=" + lastName +

                ", email=" + email +

                '}';

    }

}

package com.luv2code.springboot.cruddemo.dao;

import com.luv2code.springboot.cruddemo.entity.Employee;

import java.util.List;

public interface EmployeeDAO {

    public List<Employee> findAll();

    public Employee findById (int theId);

    public void save(Employee theEmployee);

    public void deleteById(int theId);

}

package com.luv2code.springboot.cruddemo.dao;

import java.util.List;

import com.luv2code.springboot.cruddemo.entity.Employee;

import org.hibernate.Session;

import org.hibernate.query.Query;

import org.springframework.beans.factory.annotation.Autowired;

import org.springframework.stereotype.Repository;

import javax.persistence.EntityManager;

import javax.transaction.Transactional;

@Repository

public class EmployeeDAOHibernateImpl implements EmployeeDAO{

    // define field for entitymanager

    private EntityManager entityManager;

    // setup constructor injection

    @Autowired

    public EmployeeDAOHibernateImpl(EntityManager theEntityManager) {

        entityManager = theEntityManager;

    }

    @Override

    public List<Employee> findAll() {

        // get the current hibernate session

        Session currentSession = entityManager.unwrap(Session.class);

        // create a query

        Query<Employee> theQuery =

                currentSession.createQuery("from Employee", Employee.class);

        // execute query and get result list

        List<Employee> employees = theQuery.getResultList();

        // return the results

        return employees;

    }

    @Override

    public Employee findById(int theId) {

        Session crtSession = entityManager.unwrap(Session.class);

        Employee theEmployee = crtSession.get(Employee.class, theId);

        return theEmployee;

    }

    @Override

    public void save(Employee theEmployee) {

        Session crtSession = entityManager.unwrap(Session.class);

        crtSession.saveOrUpdate(theEmployee);

    }

    @Override

    public void deleteById(int theId) {

        Session crtSession = entityManager.unwrap(Session.class);

        Query theQuery =

                crtSession.createQuery("delete from Employee where id=:employeeId");

        theQuery.setParameter("employeeId", theId);

        theQuery.executeUpdate();

    }

}

package com.luv2code.springboot.cruddemo.service;

import com.luv2code.springboot.cruddemo.entity.Employee;

public interface EmployeeService {

    public List<Employee> findAll();

    public Employee findById(int theId);

    public void save (Employee theEmployee);

    public void deleteById(int theId);

}

package com.luv2code.springboot.cruddemo.service;

import com.luv2code.springboot.cruddemo.dao.EmployeeDAO;

import com.luv2code.springboot.cruddemo.entity.Employee;

import org.springframework.beans.factory.annotation.Autowired;

import org.springframework.transaction.annotation.Transactional;

public class EmployeeServiceImpl implements EmployeeService{

    private EmployeeDAO employeeDAO;

    @Autowired

    public EmployeeServiceImpl (EmployeeDAO theEmployeeDAO) {

        employeeDAO = theEmployeeDAO;

    }

    @Override

    @Transactional

    public List<Employee> findAll() {

        return employeeDAO.findAll();

    }

    @Override

    @Transactional

    public Employee findById(int theId) {

        return employeeDAO.findById(theId);

    }

    @Override

    @Transactional

    public void save(Employee theEmployee) {

        employeeDAO.save(theEmployee);

    }

    @Override

    @Transactional

    public void deleteById(int theId) {

        employeeDAO.deleteById(theId);

    }

}

package com.luv2code.springboot.cruddemo.rest;

import com.luv2code.springboot.cruddemo.entity.Employee;

import com.luv2code.springboot.cruddemo.service.EmployeeService;

import org.springframework.beans.factory.annotation.Autowired;

import org.springframework.web.bind.annotation.*;

@RestController

@RequestMapping("/api")

public class EmployeeRestController {

    private EmployeeService employeeService;

    @Autowired

    public EmployeeRestController (EmployeeService theEmployeeService) {

        employeeService = theEmployeeService;

    }

    // export "/employees" and return list of employees

    @GetMapping("/employees/{employeeId}")

    public List<Employee> findAll () {

        return employeeService.findAll();

    }

    // add mapping for GET /employee/{employeeId}

    public Employee getEmployee (@PathVariable int employeeId) {

        Employee theEmployee = employeeService.findById(employeeId);

        if (theEmployee == null) {

            throw new RuntimeException("Employee id not found - " + employeeId);

        }

        return theEmployee;

    }

    // add mapping for POST /employees - and new employee

    @PostMapping("/employees")

    public Employee addEmployee (@RequestBody Employee theEmployee) {

        // also just in case they pass an id in JSON ... set id to 0

        // this is to force a save of new item ... instead of update

        theEmployee.setId(0);

        // if this is update operation, it will update the id

        employeeService.save(theEmployee);

        return theEmployee;

    }

    // add mapping for PUT /employees - update existing employee

    @PutMapping("/employees")

    public Employee updateEmployee (@RequestBody Employee theEmployee) {

        employeeService.save(theEmployee);

        return theEmployee;

    }

    // delete mapping for DELETE /employees/{employeeId} - delete an existing employee

    @DeleteMapping("/employees/{employeeId}")

    public String deleteEmployee (@PathVariable int employeeId) {

        Employee tempEmployee = employeeService.findById(employeeId);

        if (tempEmployee == null) {

            throw new RuntimeException("Employee id not found - " + employeeId);

        }

        employeeService.deleteById(employeeId);

        return "Deleted employee id - " + employeeId;

    }

}