Hibernate EntityManager

Java Persistence API（JPA）是EJB3.0规范之一，定义了对数据库数据进行持久化操作的接口。HIbernate

使用HIbernate Annotation和Hibernate EntityManager实现JPA。

下载HIbernate EntityManager：

得到的jar包：

        hibernate-entitymanager.jar

　　　hibernate-archive-browing.jar

Product.java

package com.b510.examples;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.Table;
import org.hibernate.annotations.GenericGenerator;

@Entity
@Table(name = "product", catalog = "users")
public class Product implements java.io.Serializable {

    private static final long serialVersionUID = -1546206493725028472L;
    private Integer id;
    private Category category;
    private String name;
    private String price;
    private String descripton;

    public Product() {
    }

    public Product(Category category, String name, String price,
            String descripton) {
        this.category = category;
        this.name = name;
        this.price = price;
        this.descripton = descripton;
    }

    @GenericGenerator(name = "generator", strategy = "increment")
    @Id
    @GeneratedValue(generator = "generator")
    @Column(name = "id", unique = true, nullable = false)
    public Integer getId() {
        return this.id;
    }

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

    // 延迟加载：多对一方式
    // 关联信息：外键name = "category_id"
    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "category_id")
    public Category getCategory() {
        return this.category;
    }

    public void setCategory(Category category) {
        this.category = category;
    }

    @Column(name = "name", length = 500)
    public String getName() {
        return this.name;
    }

    public void setName(String name) {
        this.name = name;
    }

    @Column(name = "price", length = 10)
    public String getPrice() {
        return this.price;
    }

    public void setPrice(String price) {
        this.price = price;
    }

    @Column(name = "descripton", length = 500)
    public String getDescripton() {
        return this.descripton;
    }

    public void setDescripton(String descripton) {
        this.descripton = descripton;
    }

}

src/META-INF/persistence.xml

<?xml version="1.0" encoding="UTF-8"?>
<persistence version="1.0"
    xmlns:persistence="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.23.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://java.sun.com/xml/ns/persistence persistence_1_0.xsd ">

    <persistence-unit name="entityManager">
        <provider>org.hibernate.ejb.HibernatePersisttence
        </provider>
        <properties>
            <property name="hibernate.archive.autodetection" value="class, hbm" />
            <property name="hibernate.show_sql" value="true" />
            <property name="hibernate.formate_sql" value="true" />
            <property name="hibernate.dialect" value="org.hibernate.dialect.MySQLDialect" />
            <property name="hibernate.connection.driver_class" value="com.mysql.jdbc.Driver" />
            <property name="hibernate.connection.url" value="jdbc:mysql://localhost:3307/users" />
            <property name="hibernate.connection.username" value="root" />
            <property name="hibernate.connection.password" value="root" />
        </properties>
    </persistence-unit>
</persistence>


 

测试代码：

HibernateTestEntityManager.java

/**
 * 
 */
package com.b510.examples;

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

/**
 * 
 * @author XHW
 * 
 * @date 2011-7-20
 * 
 */
public class HibernateTestEntityManager {

    /**
     * @param args
     */
    public static void main(String[] args) {
        new HibernateTestEntityManager().add();
    }

    public void add() {
        EntityManagerFactory emf = Persistence
                .createEntityManagerFactory("entityManager");
        EntityManager em = emf.createEntityManager();
        Product p = new Product();

        p.setName("Hibernate EntityManager");
        p.setPrice("12");
        p.setDescripton("Hibernate EntityManager test");

        EntityTransaction tx = em.getTransaction();
        tx.begin();
        // 保存p对象
        em.persist(p);
        tx.commit();
    }

}