Using JPA + eclipse link to operate PostgreSQL database

Posted by rubenc on Thu, 19 Mar 2020 16:55:47 +0100

First, make sure you have PostgreSQL installed. You can refer to my article PostgreSQL literacy tutorial.

Create a new JPA project using Eclipse:

The Platform selects eclipse link as one of the provider s of JPA.

The automatically generated project in Eclipse is shown below:

Overwrite the automatically generated xml with the contents of the following xml:

<?xml version="1.0" encoding="UTF-8"?>
<persistence version="2.0" xmlns="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd">
    <persistence-unit name="jerryjpa" transaction-type="RESOURCE_LOCAL">
        <provider>org.eclipse.persistence.jpa.PersistenceProvider</provider>
        <class>jpatest.Person</class>
        <properties>
            <property name="eclipselink.ddl-generation" value="create-tables" />
            <property name="javax.persistence.jdbc.url" value="jdbc:postgresql://localhost:5432/postgres"/>         
            <property name="javax.persistence.jdbc.driver" value="org.postgresql.Driver"/>  
            <property name="javax.persistence.jdbc.user" value="postgres"/>  
            <property name="javax.persistence.jdbc.password" value="test_password"/> 
        </properties>
    </persistence-unit>
</persistence>

Create a new Java class:


package jpatest;

import javax.persistence.Basic;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.NamedQuery;
import javax.persistence.Table;

@Entity
@Table(name = "T_PERSON")
@NamedQuery(name = "AllPersons", query = "select p from Person p")
public class Person {
    @Id
    @GeneratedValue
    private long id;
    @Basic
    private String firstName;
    @Basic
    private String lastName;

    public long getId() {
        return id;
    }

    public void setId(long newId) {
        this.id = newId;
    }

    public String getFirstName() {
        return this.firstName;
    }

    public void setFirstName(String newFirstName) {
        this.firstName = newFirstName;
    }

    public String getLastName() {
        return this.lastName;
    }

    public void setLastName(String newLastName) {
        this.lastName = newLastName;
    }
}

Now you can write the test program:

package jpatest;

import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.EntityTransaction;
import javax.persistence.Persistence;

public class Test {
public static void main(String[] args) {
		
        String persistenceUnitName = "jerryjpa";  
        EntityManagerFactory factory = Persistence.createEntityManagerFactory(persistenceUnitName);  
        EntityManager entityManager = factory.createEntityManager();  
        EntityTransaction transaction = entityManager.getTransaction();  
        transaction.begin();  
       
        Person user = new Person();  
        user.setFirstName("Jerry_SAP");
        user.setLastName("Wang");
        entityManager.persist(user);  
        
        transaction.commit();  
        entityManager.close();  
        factory.close();  
		
		System.out.println("done");
	}
}

After successful execution, you can see the record of inserting JPA into the database in the test Java program on the Admin UI of PostgreSQL: