Spring Data JPA – Find Records From MySQL

Spring Boot is built on the top of the spring and contains all the features of spring. And is becoming a favorite of developers these days because of its rapid production-ready environment which enables the developers to directly focus on the logic instead of struggling with the configuration and setup. Spring Boot is a microservice-based framework and making a production-ready application in it takes very little time. Java persistence API is like an interface that contains most of the methods that are used for data manipulation in the MySQL table and hibernate is the implementation of these methods, So we don’t have to create any method for inserting the data in the MySQL. In this article, we will discuss how to find the particular record from the MySQL table using the primary key.

JPARepositery<>.findById() method is used for finding the records from mysql.

Step By Step Implementation

Go to Spring Initializr Fill in the details as per the requirements. Click on Generate which will download the starter project. Extract the zip file.

Pom.xml

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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.6.1</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.example</groupId>
    <artifactId>SpringBootApp</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>SpringBootApp</name>
    <description>Demo project for Spring Boot</description>
    <properties>
        <java.version>11</java.version>
    </properties>
    <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>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>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

Extract the zip file. Now open a suitable IDE and then go to File->New->Project from existing sources->Springbootapp and select pom.xml. Click on import changes on prompt and wait for the project to sync

Note: In the Import Project for Maven window, make sure you choose the same version of JDK which you selected while creating the project. For database operation we have to configure the Spring application with the database also it is required to add configuration of the database before executing the Spring project. All the configuration is added in the file application.properties of the Spring project. 

application.properties file:

spring.datasource.url=jdbc:mysql://localhost:3306/user
spring.datasource.username=root
spring.datasource.password=Aayush
spring.jpa.hibernate.ddl-auto=update 

Project Structure:

User.java: (Table structure of the MySQL table)

Java

@Entity
public class User {
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    int id;
    String name;
    User() {}
    User(int id, String name)
    {
        this.id = id;
        this.name = name;
    }
}

UserRepo:(This file is used for extending the JPA methods with hibernate implementation)

Java

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

interface UserRepo extends JpaRepository<User,Integer> {

}

SpringBootAppApplication:

Java

package com.example.SpringBootApp;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.CommandLineRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

import java.util.Optional;

@SpringBootApplication
public class SpringBootAppApplication implements  CommandLineRunner {

    @Autowired
    UserRepo ob;
    public static void main(String[] args) {
        SpringApplication.run(SpringBootAppApplication.class, args);
    }

    @Override
    public void run(String... args) throws Exception {
        User record=new User(1,"Aayush");
        ob.save(record);
        Optional<User> record=ob.findById(1);
        record.stream().forEach(e->{
            System.out.print(e.id+" "+e.name);
        });

    }
}

Run the main application: