使用JPA + Eclipselink操作PostgreSQL數(shù)據(jù)庫(kù)

xavier 發(fā)布于2019-07-25 12:37 / 769人閱讀

摘要：首先確保您已經(jīng)安裝了。您可以參考我這篇文章掃盲教程。使用創(chuàng)建一個(gè)新的選擇，作為的之一。

首先確保您已經(jīng)安裝了PostgreSQL。您可以參考我這篇文章PostgreSQL掃盲教程。

使用Eclipse創(chuàng)建一個(gè)新的JPA project：

Platform選擇EclipseLink，作為JPA的provider之一。

在Eclipse里自動(dòng)生成的project如下圖所示：

用下列xml的內(nèi)容覆蓋自動(dòng)生成的xml：



    
        org.eclipse.persistence.jpa.PersistenceProvider
        jpatest.Person

新建一個(gè)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;
    }
}

現(xiàn)在可以寫測(cè)試程序了：

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");
    }
}

成功執(zhí)行后，在PostgreSQL的Admin UI上能看到測(cè)試Java程序里用JPA插入數(shù)據(jù)庫(kù)的記錄：

本文完整的源代碼和所需的庫(kù)文件可以在我的github上找到。

eclipselink-2.5.1.jar

javax.persistence-2.1.0.jar

postgresql-42.1.1.jar