Hibernate注解
说明文档：
英文：http://docs.jboss.org/hibernate/annotations/3.5/reference/en/html_single/
中文：http://docs.jboss.org/hibernate/annotations/3.4/reference/zh_cn/html_single/
下载：hibernate annotation 3.4.0 GA
得到：hibernate-annotations.jar
hibernate-commons-annotation.jar
ejb3-persistence.jar
数据库：mysql
category表：id，name，description <Pk>id
product表：id,name ,price, description ,category_id <pk>id <fk>category_id
新建java project项目：
Add Hibernate Capabilities
hibernate.cfg.xml
<?xml version='1.0' encoding='UTF-8'?> <!DOCTYPE hibernate-configuration PUBLIC "-//Hibernate/Hibernate Configuration DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd"> <!-- Generated by MyEclipse Hibernate Tools. --> <hibernate-configuration> <session-factory> <property name="dialect"> org.hibernate.dialect.MySQLDialect </property> <property name="connection.url"> jdbc:mysql://localhost:3307/users </property> <property name="connection.username">root</property> <property name="connection.password">root</property> <property name="connection.driver_class"> com.mysql.jdbc.Driver </property> <property name="myeclipse.connection.profile"> mysqlusers </property> <property name="format_sql">true</property> <property name="show_sql">true</property> <property name="current_session_context_class">thread</property> <mapping class="com.b510.examples.Product" /> <mapping class="com.b510.examples.Category" /> </session-factory> </hibernate-configuration>
利用Hibernate的逆向工程生成：
Category.java and Product.java
Category.java
package com.b510.examples; import java.util.HashSet; import java.util.Set; // 标准注解 import javax.persistence.CascadeType; import javax.persistence.Column; import javax.persistence.Entity; import javax.persistence.FetchType; import javax.persistence.GeneratedValue; import javax.persistence.Id; import javax.persistence.OneToMany; import javax.persistence.Table; //增加的注解 import org.hibernate.annotations.GenericGenerator; //当前的类是一个持久化类，是Category这个类。他映射了一个表category。所对应的 数据库是users //这句：@Table(name = "category", catalog = "users") 可以省略 @Entity @Table(name = "category", catalog = "users") public class Category implements java.io.Serializable { private static final long serialVersionUID = 3240281547213597385L; private Integer id; private String name; private String description; private Set<Product> products = new HashSet<Product>(0); public Category() { } public Category(String name, String description, Set<Product> products) { this.name = name; this.description = description; this.products = products; } // 主键 ：@Id 主键生成方式：strategy = "increment" //映射表中id这个字段，不能为空，并且是唯一的 @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; } //映射表中name这个字段 ，长度是500 @Column(name = "name", length = 500) public String getName() { return this.name; } public void setName(String name) { this.name = name; } //映射表中description这个字段 ，长度是500 @Column(name = "description", length = 500) public String getDescription() { return this.description; } public void setDescription(String description) { this.description = description; } //级联操作：cascade = CascadeType.ALL //延迟加载：fetch = FetchType.LAZY //映射：mappedBy = "category" //一对多方式 @OneToMany(cascade = CascadeType.ALL, fetch = FetchType.LAZY, mappedBy = "category") public Set<Product> getProducts() { return this.products; } public void setProducts(Set<Product> products) { this.products = products; } }
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; } }
测试代码：
HibernateTest.java
/** * */ package com.b510.examples; import java.util.Set; import org.hibernate.Session; import org.hibernate.SessionFactory; import org.hibernate.cfg.AnnotationConfiguration; import org.hibernate.cfg.Configuration; /** * * @author XHW * * @date 2011-7-20 * */ public class HibernateTest { public static void main(String[] args) { HibernateTest test=new HibernateTest(); test.add(); test.find(); } public void add(){ Configuration config=new AnnotationConfiguration(); config.configure(); SessionFactory sessionFactory=config.buildSessionFactory(); Session session=sessionFactory.getCurrentSession(); session.beginTransaction(); Category c=(Category)session.get(Category.class, 5); Product p=new Product(); p.setName("计算机科学与技术"); p.setPrice("123"); p.setDescripton("计算机科学与技术,好啊，真是红啊"); p.setCategory(c); c.getProducts().add(p); session.save(p); session.getTransaction().commit(); } public void find(){ Configuration config=new AnnotationConfiguration(); config.configure(); SessionFactory sessionFactory=config.buildSessionFactory(); Session session=sessionFactory.getCurrentSession(); session.beginTransaction(); Category c=(Category)session.get(Category.class, 5); System.out.println("id: "+c.getId()+" name:"+c.getName()); Set<Product> p=c.getProducts(); for(Product product:p){ System.out.println("id:"+product.getId()+" name:"+product.getName()+" description:"+product.getDescripton()); } session.getTransaction().commit(); } }
运行效果：
log4j:WARN No appenders could be found for logger (org.hibernate.cfg.annotations.Version). log4j:WARN Please initialize the log4j system properly. Hibernate: select category0_.id as id1_0_, category0_.description as descript2_1_0_, category0_.name as name1_0_ from users.category category0_ where category0_.id=? Hibernate: select products0_.category_id as category5_1_, products0_.id as id1_, products0_.id as id0_0_, products0_.category_id as category5_0_0_, products0_.descripton as descripton0_0_, products0_.name as name0_0_, products0_.price as price0_0_ from users.product products0_ where products0_.category_id=? Hibernate: select max(id) from product Hibernate: insert into users.product (category_id, descripton, name, price, id) values (?, ?, ?, ?, ?) Hibernate: select category0_.id as id5_0_, category0_.description as descript2_5_0_, category0_.name as name5_0_ from users.category category0_ where category0_.id=? id: 5 name:xml33 Hibernate: select products0_.category_id as category5_1_, products0_.id as id1_, products0_.id as id4_0_, products0_.category_id as category5_4_0_, products0_.descripton as descripton4_0_, products0_.name as name4_0_, products0_.price as price4_0_ from users.product products0_ where products0_.category_id=?
id:9 name:计算机科学与技术 description:计算机科学与技术,好啊，真是红啊
