Spring Boot Crud Operations Example

YatinJanuary 29th, 2019Last Updated: February 18th, 2019

10 1,152 6 minutes read

Welcome readers, in this tutorial, we will explore the crud operations in spring boot module of the spring framework.

1. Introduction

Spring Boot is a module that provides rapid application development feature to the spring framework including auto-configuration, standalone-code, and production-ready code
It creates applications that are packaged as jar and are directly started using embedded servlet container (such as Tomcat, Jetty or Undertow). Thus, no need to deploy the war files
It simplifies the maven configuration by providing the starter template and helps to resolve the dependency conflicts. It automatically identifies the required dependencies and imports them in the application
It helps in removing the boilerplate code, extra annotations, and xml configurations
It provides a powerful batch processing and manages the rest endpoints
It provides an efficient jpa-starter library to effectively connect the application with the relational databases

Now, open the eclipse ide and let us see how to implement this tutorial in the spring boot module using the jpa-starter library to communicate with a relational database.

2. Spring Boot Crud Operations Example

Here is a systematic guide for implementing this tutorial.

2.1 Tools Used

We are using Eclipse Kepler SR2, JDK 8, and Maven.

2.2 Project Structure

In case you are confused about where you should create the corresponding files or folder, let us review the project structure of the spring boot application.

Spring Boot Crud Operations - Application Structure — Fig. 1: Application Structure

3. Creating a Spring Boot application

Below are the steps involved in developing the application.

3.1 Maven Dependencies

Here, we specify the dependencies for the Spring Boot, Spring Boot JPA, and MySQL connector. Maven will automatically resolve the other dependencies. The updated file will have the following code.

pom.xml

<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 http://maven.apache.org/maven-v4_0_0.xsd">
	<modelVersion>4.0.0</modelVersion>
	<groupId>com.springboot.crud</groupId>
	<artifactId>Springbootcrudoperation</artifactId>
	<packaging>war</packaging>
	<version>0.0.1-SNAPSHOT</version>
	<name>Springbootcrudoperation Maven Webapp</name>
	<url>http://maven.apache.org</url>

	<!-- Spring boot parent dependency jar -->
	<parent>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-parent</artifactId>
		<version>2.1.1.RELEASE</version>
	</parent>
	<dependencies>
		<!-- Spring boot web mvc jar -->
		<!-- Automatically adds tomcat and jackson-databind jars -->
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-web</artifactId>
		</dependency>
		<!-- Spring boot jpa jar -->
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-data-jpa</artifactId>
		</dependency>
		<!-- Mysql database jar -->
		<dependency>
			<groupId>mysql</groupId>
			<artifactId>mysql-connector-java</artifactId>
		</dependency>
	</dependencies>
	<build>
		<finalName>Springbootcrudoperation</finalName>
	</build>
</project>

3.2 Application Properties

Create a new properties file at the location: Springbootcrudoperation/src/main/resources/ and add the following code to it.

application.properties

## Spring datasource.
spring.datasource.driver.class=com.mysql.cj.jdbc.Driver
spring.datasource.url=jdbc:mysql://localhost:3306/paramount
spring.datasource.username=root
spring.datasource.password=

## Hibernate properties.
spring.jpa.properties.hibernate.dialect=org.hibernate.dialect.MySQL5Dialect

## Show sql query.
spring.jpa.show-sql=true

## Hibernate ddl auto.
spring.jpa.hibernate.ddl-auto=validate

3.3 Java Classes

Let us write all the java classes involved in this application.

3.3.1 Implementation/Main class

Add the following code the main class to bootstrap the application from the main method. Always remember, the entry point of the spring boot application is the class containing @SpringBootApplication annotation and the static main method.

Myapplication.java

package com.ducat.springboot.rest;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class Myapplication {

	public static void main(String[] args) {
		SpringApplication.run(Myapplication.class, args);
	}
}

3.3.2 Model class

Add the following code to the employee model class.

Employee.java

package com.ducat.springboot.rest.model;

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

import org.hibernate.annotations.DynamicInsert;
import org.hibernate.annotations.DynamicUpdate;
import org.springframework.stereotype.Component;

@Component

// Spring jpa jars.
@Entity
@Table(name= "employee")

// To increase speed and save sql statement execution time.
@DynamicInsert
@DynamicUpdate
public class Employee {

	@Id
	@GeneratedValue(strategy= GenerationType.IDENTITY)
	private int id;
	private String name;
	private String department;
	private double salary;

	public Employee() { }

	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 String getDepartment() {
		return department;
	}
	public void setDepartment(String department) {
		this.department = department;
	}
	public double getSalary() {
		return salary;
	}
	public void setSalary(double salary) {
		this.salary = salary;
	}

	@Override
	public String toString() {
		return "Employee [id=" + id + ", name=" + name + ", department=" + department + ", salary=" + salary + "]";
	}
}

3.3.3 Data-Access-Object interface

Add the following code to the Dao interface that extends the JPA repository to automatically handle the crud queries.

Mydaorepository.java

package com.ducat.springboot.rest.dao;

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

import com.ducat.springboot.rest.model.Employee;

@Repository
public interface Mydaorepository extends JpaRepository<Employee, Integer> {

}

3.3.4 Service class

Add the following code to the service class where we will call the methods of the Dao interface to handle the sql operations.

Mydaorepository.java

package com.ducat.springboot.rest.service;

import java.util.List;
import java.util.Optional;

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

import com.ducat.springboot.rest.dao.Mydaorepository;
import com.ducat.springboot.rest.model.Employee;

@Service
public class Myserviceimpl implements Myservice {

	@Autowired
	Mydaorepository dao;

	@Override
	public List<Employee> getEmployees() {
		return dao.findAll();
	}
	@Override
	public Optional<Employee> getEmployeeById(int empid) {
		return dao.findById(empid);
	}
	@Override
	public Employee addNewEmployee(Employee emp) {
		return dao.save(emp);
	}
	@Override
	public Employee updateEmployee(Employee emp) {
		return dao.save(emp);
	}
	@Override
	public void deleteEmployeeById(int empid) {
		dao.deleteById(empid);
	}
	@Override
	public void deleteAllEmployees() {
		dao.deleteAll();
	}
}

3.3.5 Controller class

Add the following code to the controller class designed to handle the incoming requests. The class is annotated with the @RestController annotation where every method returns a domain object as a json response instead of a view.

Mycontroller.java

package com.ducat.springboot.rest.controller;

import java.util.List;
import java.util.Optional;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;

import com.ducat.springboot.rest.model.Employee;
import com.ducat.springboot.rest.service.Myservice;

@RestController
public class Mycontroller {

	@Autowired
	Myservice service;

	@RequestMapping(value= "/employee/all", method= RequestMethod.GET)
	public List<Employee> getEmployees() {
		System.out.println(this.getClass().getSimpleName() + " - Get all employees service is invoked.");
		return service.getEmployees();
	}

	@RequestMapping(value= "/employee/{id}", method= RequestMethod.GET)
	public Employee getEmployeeById(@PathVariable int id) throws Exception {
		System.out.println(this.getClass().getSimpleName() + " - Get employee details by id is invoked.");

		Optional<Employee> emp =  service.getEmployeeById(id);
		if(!emp.isPresent())
			throw new Exception("Could not find employee with id- " + id);

		return emp.get();
	}

	@RequestMapping(value= "/employee/add", method= RequestMethod.POST)
	public Employee createEmployee(@RequestBody Employee newemp) {
		System.out.println(this.getClass().getSimpleName() + " - Create new employee method is invoked.");
		return service.addNewEmployee(newemp);
	}

	@RequestMapping(value= "/employee/update/{id}", method= RequestMethod.PUT)
	public Employee updateEmployee(@RequestBody Employee updemp, @PathVariable int id) throws Exception {
		System.out.println(this.getClass().getSimpleName() + " - Update employee details by id is invoked.");

		Optional<Employee> emp =  service.getEmployeeById(id);
		if (!emp.isPresent())
			throw new Exception("Could not find employee with id- " + id);

		/* IMPORTANT - To prevent the overriding of the existing value of the variables in the database, 
		 * if that variable is not coming in the @RequestBody annotation object. */		
		if(updemp.getName() == null || updemp.getName().isEmpty())
			updemp.setName(emp.get().getName());
		if(updemp.getDepartment() == null || updemp.getDepartment().isEmpty())
			updemp.setDepartment(emp.get().getDepartment());
		if(updemp.getSalary() == 0)
			updemp.setSalary(emp.get().getSalary());

		// Required for the "where" clause in the sql query template.
		updemp.setId(id);
		return service.updateEmployee(updemp);
	}

	@RequestMapping(value= "/employee/delete/{id}", method= RequestMethod.DELETE)
	public void deleteEmployeeById(@PathVariable int id) throws Exception {
		System.out.println(this.getClass().getSimpleName() + " - Delete employee by id is invoked.");

		Optional<Employee> emp =  service.getEmployeeById(id);
		if(!emp.isPresent())
			throw new Exception("Could not find employee with id- " + id);

		service.deleteEmployeeById(id);
	}

	@RequestMapping(value= "/employee/deleteall", method= RequestMethod.DELETE)
	public void deleteAll() {
		System.out.println(this.getClass().getSimpleName() + " - Delete all employees is invoked.");
		service.deleteAllEmployees();
	}
}

4. Run the Application

As we are ready with all the changes, let us compile the spring boot project and run the application as a java project. Right click on the Myapplication.java class, Run As -> Java Application.

Spring Boot Crud Operations - Application Run — Fig. 2: Application Run

Developers can debug the example and see what happens after every step. Enjoy!

5. Project Demo

Open the postman tool and hit the following urls to display the data in the json format.

// Get all employees
http://localhost:8080/employee/all

// Get employee by id
http://localhost:8080/employee/1003

// Create new employee
http://localhost:8080/employee/add

// Update existing employee by id
http://localhost:8080/employee/update/1008

// Delete employee by id
http://localhost:8080/employee/delete/1002

// Delete all employees
http://localhost:8080/employee/deleteall

That is all for this tutorial and I hope the article served you whatever you were looking for. Happy Learning and do not forget to share!

6. Conclusion

In this section, developers learned how to create a spring boot application and perform the basic crud operations using the spring-jpa-starter library.

6.1 Important points

We instructed the hibernate to connect to a mysql database and use the MySQL5Dialect for generating the optimized sql queries
spring.jpa.hibernate.ddl-auto=validate will instruct the hibernate to validate the table schema at the application startup
spring.jpa.show-sql=true will instruct the hibernate framework to log all the SQL statements on the console
Developers can change the data-source details as per their need
Few more. . . . . . .

Developers can download the sample application as an Eclipse project in the Downloads section.