Spring Boot - save(), findById(), findAll(), deleteById() Tutorial

In this tutorial, we will learn how to use save(), findById(), findAll(), and deleteById() methods of JpaRepository (Spring data JPA) with Spring Boot.
As we know that Spring is a popular Java application framework. Spring Boot is an effort to create stand-alone, production-grade Spring-based applications with minimal effort.

Spring Data

Spring Data JPA is not a JPA provider. It is a library/framework that adds an extra layer of abstraction on the top of our JPA provider (like Hibernate).

JpaRepository Interface

JpaRepository is JPA specific extension of Repository. It contains the full API of CrudRepository and PagingAndSortingRepository. So it contains API for basic CRUD operations and also API for pagination and sorting.

Spring boot save(), findById(), findAll(), deleteById() Example

The following Spring Boot application manages an Employee entity with JpaRepository. The data is saved in the H2 database. The application is a console program.

1. Create a Spring Boot Application

There are many ways to create a Spring Boot application. You can refer below articles to create a Spring Boot application.

2. Pom Dependencies - pom.xml

<?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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
 <modelVersion>4.0.0</modelVersion>

 <groupId>net.guides.springboot2</groupId>
 <artifactId>springboot-jparepository-example</artifactId>
 <version>0.0.1-SNAPSHOT</version>
 <packaging>jar</packaging>

 <parent>
     <groupId>org.springframework.boot</groupId>
         <artifactId>spring-boot-starter-parent</artifactId>
         <version>2.0.5.RELEASE</version>
         <relativePath /> <!-- lookup parent from repository -->
 </parent>

 <properties>
      <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
      <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
     <java.version>1.8</java.version>
 </properties>

 <dependencies>
     <dependency>
          <groupId>org.springframework.boot</groupId>
          <artifactId>spring-boot-starter-data-jpa</artifactId>
     </dependency>
 
     <dependency>
          <groupId>com.h2database</groupId>
          <artifactId>h2</artifactId>
          <scope>runtime</scope>
     </dependency> 
 </dependencies>

 <build>
     <plugins>
         <plugin>
              <groupId>org.springframework.boot</groupId>
              <artifactId>spring-boot-maven-plugin</artifactId>
         </plugin>
     </plugins>
 </build>
</project>
The spring-boot-starter-data-jpa is a starter for using Spring Data JPA with Hibernate.

3. resources/application.properties

spring.main.banner-mode=off
logging.pattern.console=%clr(%d{yy-MM-dd E HH:mm:ss.SSS}){blue} %clr(%-5p) %clr(%logger{0}){blue} %clr(%m){faint}%n
The application.properties is the main Spring Boot configuration file. 
With the spring.main.banner-mode the property we turn off the Spring banner. The logging.pattern.consoleDefines the log pattern for the console.

4. JPA Entity - Employee.java

package net.guides.springboot.jparepository.model;

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

@Entity
@Table(name = "employees")
public class Employee {

    private long id;
    private String firstName;
    private String lastName;
    private String emailId;
 
    public Employee() {
  
    }
 
    public Employee(String firstName, String lastName, String emailId) {
        this.firstName = firstName;
        this.lastName = lastName;
        this.emailId = emailId;
    }
 
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    public long getId() {
        return id;
    }
    public void setId(long id) {
        this.id = id;
    }
 
    @Column(name = "first_name", nullable = false)
    public String getFirstName() {
        return firstName;
    }
    public void setFirstName(String firstName) {
        this.firstName = firstName;
    }
 
    @Column(name = "last_name", nullable = false)
    public String getLastName() {
        return lastName;
    }
    public void setLastName(String lastName) {
        this.lastName = lastName;
    }
 
    @Column(name = "email_address", nullable = false)
    public String getEmailId() {
        return emailId;
    }
    public void setEmailId(String emailId) {
        this.emailId = emailId;
    }

    @Override
    public String toString() {
        return "Employee [id=" + id + ", firstName=" + firstName + ", lastName=" + lastName + ", emailId=" + emailId
    + "]";
    }
 
}

5. Service Layer

EmployeeService.java

package net.guides.springboot.jparepository.service;

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

import net.guides.springboot.jparepository.model.Employee;

public interface EmployeeService {

    List < Employee > findAll();

    void save(Employee employee);

    Optional < Employee > findById(Long id);

    void delete(long id);
}

EmployeeServiceImpl.java

package net.guides.springboot.jparepository.service;

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

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

import net.guides.springboot.jparepository.model.Employee;
import net.guides.springboot.jparepository.repository.EmployeeRepository;

@Service
public class EmployeeServiceImpl implements EmployeeService {

    @Autowired
    private EmployeeRepository employeeRepository;

    @Override
    public Optional < Employee > findById(Long id) {
        return employeeRepository.findById(id);
    }

    @Override
    public void save(Employee employee) {
        employeeRepository.save(employee);
    }

    @Override
    public List < Employee > findAll() {
        return employeeRepository.findAll();
    }

    @Override
    public void delete(long id) {
        employeeRepository.deleteById(id);
    }
}

6. JPA Repository - EmployeeRepository.java

The EmployeeRepository extends from the JpaRepository. It provides the type of the entity and of its primary key.
package net.guides.springboot.jparepository.repository;

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

import net.guides.springboot.jparepository.model.Employee;

@Repository
public interface EmployeeRepository extends JpaRepository<Employee, Long>{

}

7. MyRunner.java

package net.guides.springboot.jparepository;

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

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.CommandLineRunner;
import org.springframework.stereotype.Component;

import net.guides.springboot.jparepository.model.Employee;
import net.guides.springboot.jparepository.service.EmployeeService;

@Component
public class MyRunner implements CommandLineRunner {

    private static final Logger logger = LoggerFactory.getLogger(MyRunner.class);

    @Autowired
    private EmployeeService emplyeeService;
    @Override
    public void run(String...args) throws Exception {

        emplyeeService.save(new Employee("Ramesh", "Fadatare", "ramesh@gmail.com"));
        emplyeeService.save(new Employee("Tom", "Cruise", "tom@gmail.com"));
        emplyeeService.save(new Employee("John", "Cena", "john@gmail.com"));
        emplyeeService.save(new Employee("tony", "stark", "stark@gmail.com"));


        long id1 = 1L;
        emplyeeService.findById(id1).ifPresent(System.out::println);

        long id2 = 5L;
        Optional < Employee > optional = emplyeeService.findById(id2);

        if (optional.isPresent()) {
            System.out.println(optional.get());
        } else {
            System.out.printf("No employee found with id %d%n", id2);
        }

        // get list of employees
        List < Employee > employees = emplyeeService.findAll();
        employees.forEach(employee -> System.out.println(employee.toString()));

        // delete employee by id
        emplyeeService.delete(3L);
    }
}

8. Running Spring Boot Application

The Application sets up the Spring Boot application. Let's run this Application class:
package net.guides.springboot.jparepository;

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

@SpringBootApplication
public class Application {

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

9. Output


Comments