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The JPA (Java Persistence API) is a Java specification for accessing, persisting, and maintaining data between Java objects and a relational database. It can provide a framework for assigning Java objects to database tables and simplify database operations in Java applications.
Inserting an entity into the database is the fundamental operation and the entity represents the data entity in the application, and it can typically be mapped to the database table. Inserting the entity involves creating a new record in the database table to store the entity data.
Inserting the entities is essential for persisting data to the database and it can maintain the state of the application data and it can allow the applications to store the user inputs and perform the data processing and also maintains the data consistency across the different transactions.
Step 1 : We need to create the entity class that can represents the data you want to the persist into the database. Entity class is annotated with @Entity and define the fields of the entity class includes the primary key annotated with @Id .
Example:
@Entity
public class Product {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
private String name;
private double price;
// Getters and Setters
}
Step 2 : We can create the EntityManager interface can be used to the interact with persistence context and it can performs the database operations and also obtain the istance of EntityManager from the EntityManagerFactory .
EntityManagerFactory emf= Persistence.createEntityManagerFactory("jpa-example");
EntityManager em= entityManagerFactory.createEntityManager();
Step 3 : Before the performing any database operations begins the transcation to be ensure that the operations are the atomic and consistent and start the new transcation using EntityTranscation interface.
EntityTransaction trs= entityManager.getTransaction();
trs.begin();
Step 4 : We can use the persist( ) method of the EntityManager interface to the insert the entity into the database and this method can be add the entity to persistence context and it can schedule the insert operation for the entity in database up to the transaction commit.
Ex: Persist the Entity
Product product = new Product();
product.setName("Smart Phone");
product.setPrice(15000.0);
entityManager.persist(product);
Step 5: Once complete the database operation then commit the transaction to apply the changes of database. Now, we can commit the transaction using commit() method of the EntityTransaction interface.
Example: Commit the Transaction
transaction.commit();
Step 6 : Close the EntityManager
entityManager.close();
By following the above steps, we can insert the entity into the database using JPA in the Java applications.
Step 1 : First, we can create the JPA project using the IntellijIdea named as entity-demo of the project.
Step 2 : Now, we can add the below dependencies into the JPA project.
Dependencies:
<dependency>
<groupId>org.hibernate.orm</groupId>
<artifactId>hibernate-core</artifactId>
<version>6.0.2.Final</version>
</dependency>
<dependency>
<groupId>org.glassfish.jaxb</groupId>
<artifactId>jaxb-runtime</artifactId>
<version>3.0.2</version>
</dependency>
<dependency>
<groupId>org.junit.jupiter</groupId>
<artifactId>junit-jupiter-api</artifactId>
<version>${junit.version}</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.junit.jupiter</groupId>
<artifactId>junit-jupiter-engine</artifactId>
<version>${junit.version}</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>8.0.28</version>
</dependency>
Once the project creation completed, then the file structure will look like the below image.
Step 3 : Open persistance.xml and put the below code for the MYSQL database configuration of the database.
<?xml version="1.0" encoding="UTF-8"?>
<persistence xmlns="http://xmlns.jcp.org/xml/ns/persistence"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/persistence
http://xmlns.jcp.org/xml/ns/persistence/persistence_2_1.xsd"
version="2.1">
<persistence-unit name="jpa-example" transaction-type="RESOURCE_LOCAL">
<class>Product</class>
<properties>
<property name="javax.persistence.jdbc.url" value="jdbc:mysql://localhost:3306/example"/>
<property name="javax.persistence.jdbc.user" value="root"/>
<property name="javax.persistence.jdbc.password" value=""/>
<property name="javax.persistence.jdbc.driver" value="com.mysql.jdbc.Driver"/>
<property name="hibernate.dialect" value="org.hibernate.dialect.MySQL5Dialect"/>
<property name="hibernate.hbm2ddl.auto" value="update"/>
</properties>
</persistence-unit>
</persistence>
Step 4: Create the new Entity Java class for the creation of the entity and it named as Product.
Go to src > main > java > Product and put the below code.
import jakarta.persistence.*;
// Entity annotation specifies that the class is an entity and is mapped to a database table
@Entity
public class Product {
// Id annotation specifies the primary key of the entity
// GeneratedValue annotation provides the strategy for generating primary key values
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
// Name of the product
private String name;
// Price of the product
private double price;
// Getter method for retrieving the product id
public Long getId() {
return id;
// Setter method for setting the product id
public void setId(Long id) {
this.id = id;
// Getter method for retrieving the product name
public String getName() {
return name;
// Setter method for setting the product name
public void setName(String name) {
this.name = name;
// Getter method for retrieving the product price
public double getPrice() {
return price;
// Setter method for setting the product price
public void setPrice(double price) {
this.price = price;
Step 5: Create the new Java class and named as the Main.
Go to src > main > java > Main and put the below code.
import jakarta.persistence.EntityManager;
import jakarta.persistence.EntityManagerFactory;
import jakarta.persistence.Persistence;
public class Main {
public static void main(String[] args) {
// Obtain EntityManager instance
EntityManagerFactory emf = Persistence.createEntityManagerFactory("jpa-example");
EntityManager em = emf.createEntityManager();
// Begin transaction
em.getTransaction().begin();
// Create and persist Product entity
Product product = new Product();
product.setName("Laptop");
product.setPrice(1000.0);
em.persist(product);
// Commit transaction
em.getTransaction().commit();
// Retrieve the persisted Product entity
Product persistedProduct = em.find(Product.class, product.getId());
// Print the details of the persisted Product entity
System.out.println("Inserted Product Details:");
System.out.println("ID: " + persistedProduct.getId());
System.out.println("Name: " + persistedProduct.getName());
System.out.println("Price: " + persistedProduct.getPrice());
// Close EntityManager
em.close();
emf.close();
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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>org.example</groupId>
<artifactId>entity-demo</artifactId>
<version>1.0-SNAPSHOT</version>
<name>entity-demo</name>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<maven.compiler.target>11</maven.compiler.target>
<maven.compiler.source>11</maven.compiler.source>
<junit.version>5.9.2</junit.version>
</properties>
<dependencies>
<dependency>
<groupId>org.hibernate.orm</groupId>
<artifactId>hibernate-core</artifactId>
<version>6.0.2.Final</version>
</dependency>
<dependency>
<groupId>org.glassfish.jaxb</groupId>
<artifactId>jaxb-runtime</artifactId>
<version>3.0.2</version>
</dependency>
<dependency>
<groupId>org.junit.jupiter</groupId>
<artifactId>junit-jupiter-api</artifactId>
<version>${junit.version}</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.junit.jupiter</groupId>
<artifactId>junit-jupiter-engine</artifactId>
<version>${junit.version}</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>8.0.28</version>
</dependency>
</dependencies>
<build>
<plugins>
</plugins>
</build>
</project>
Step 6: Once the project is done, then run the application and we can get the output like the below image.
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