Hibernate Annotation (Hibernate 注解)

入：http://www.hibernate.org
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

1 <?xml version='1.0' encoding='UTF-8'?>
2 <!DOCTYPE hibernate-configuration PUBLIC
3           "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
4           "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">
5
6 <!-- Generated by MyEclipse Hibernate Tools.                   -->
7 <hibernate-configuration>
8
9  <session-factory>
10   <property name="dialect">
11    org.hibernate.dialect.MySQLDialect
12   </property>
13   <property name="connection.url">
14    jdbc:mysql://localhost:3307/users
15   </property>
16   <property name="connection.username">root</property>
17   <property name="connection.password">root</property>
18   <property name="connection.driver_class">
19    com.mysql.jdbc.Driver
20   </property>
21   <property name="myeclipse.connection.profile">
22    mysqlusers
23   </property>
24   <property name="format_sql">true</property>
25   <property name="show_sql">true</property>
26   <property name="current_session_context_class">thread</property>
27   <mapping class="com.b510.examples.Product" />
28   <mapping class="com.b510.examples.Category" />
29
30  </session-factory>
31
32 </hibernate-configuration>

利用Hibernate的逆向工程生成：

Category.java and Product.java

Category.java

1 package com.b510.examples;
2
3 import java.util.HashSet;
4 import java.util.Set;
5
6 // 标准注解
7
8 import javax.persistence.CascadeType;
9 import javax.persistence.Column;
10 import javax.persistence.Entity;
11 import javax.persistence.FetchType;
12 import javax.persistence.GeneratedValue;
13 import javax.persistence.Id;
14 import javax.persistence.OneToMany;
15 import javax.persistence.Table;
16
17 //增加的注解
18
19 import org.hibernate.annotations.GenericGenerator;
20
21 //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
22 //这句：@Table(name = "category", catalog = "users")  可以省略
23 @Entity
24 @Table(name = "category", catalog = "users")
25
26 public class Category implements java.io.Serializable {
27
28  private static final long serialVersionUID = 3240281547213597385L;
29  private Integer id;
30  private String name;
31  private String description;
32  private Set<Product> products = new HashSet<Product>(0);
33
34
35  public Category() {
36  }
37
38  public Category(String name, String description, Set<Product> products) {
39   this.name = name;
40   this.description = description;
41   this.products = products;
42  }
43
44  // 主键 ：@Id    主键生成方式：strategy = "increment"
45  //映射表中id这个字段，不能为空，并且是唯一的
46  @GenericGenerator(name = "generator", strategy = "increment")
47  @Id
48  @GeneratedValue(generator = "generator")
49  @Column(name = "id", unique = true, nullable = false)
50  public Integer getId() {
51   return this.id;
52  }
53
54  public void setId(Integer id) {
55   this.id = id;
56  }
57
58  //映射表中name这个字段 ，长度是500
59  @Column(name = "name", length = 500)
60  public String getName() {
61   return this.name;
62  }
63
64  public void setName(String name) {
65   this.name = name;
66  }
67
68  //映射表中description这个字段 ，长度是500
69  @Column(name = "description", length = 500)
70  public String getDescription() {
71   return this.description;
72  }
73
74  public void setDescription(String description) {
75   this.description = description;
76  }
77
78  //级联操作：cascade = CascadeType.ALL
79  //延迟加载：fetch = FetchType.LAZY
80  //映射：mappedBy = "category"
81  //一对多方式
82  @OneToMany(cascade = CascadeType.ALL, fetch = FetchType.LAZY, mappedBy = "category")
83  public Set<Product> getProducts() {
84   return this.products;
85  }
86
87  public void setProducts(Set<Product> products) {
88   this.products = products;
89  }
90
91 }

Product.java

1 package com.b510.examples;
2
3 import javax.persistence.Column;
4 import javax.persistence.Entity;
5 import javax.persistence.FetchType;
6 import javax.persistence.GeneratedValue;
7 import javax.persistence.Id;
8 import javax.persistence.JoinColumn;
9 import javax.persistence.ManyToOne;
10 import javax.persistence.Table;
11 import org.hibernate.annotations.GenericGenerator;
12
13
14 @Entity
15 @Table(name = "product", catalog = "users")
16 public class Product implements java.io.Serializable {
17
18  private static final long serialVersionUID = -1546206493725028472L;
19  private Integer id;
20  private Category category;
21  private String name;
22  private String price;
23  private String descripton;
24
25
26  public Product() {
27  }
28
29  public Product(Category category, String name, String price,
30    String descripton) {
31   this.category = category;
32   this.name = name;
33   this.price = price;
34   this.descripton = descripton;
35  }
36
37  @GenericGenerator(name = "generator", strategy = "increment")
38  @Id
39  @GeneratedValue(generator = "generator")
40  @Column(name = "id", unique = true, nullable = false)
41  public Integer getId() {
42   return this.id;
43  }
44
45  public void setId(Integer id) {
46   this.id = id;
47  }
48
49  //延迟加载：多对一方式
50  //关联信息：外键name = "category_id"
51  @ManyToOne(fetch = FetchType.LAZY)
52  @JoinColumn(name = "category_id")
53  public Category getCategory() {
54   return this.category;
55  }
56
57  public void setCategory(Category category) {
58   this.category = category;
59  }
60
61  @Column(name = "name", length = 500)
62  public String getName() {
63   return this.name;
64  }
65
66  public void setName(String name) {
67   this.name = name;
68  }
69
70  @Column(name = "price", length = 10)
71  public String getPrice() {
72   return this.price;
73  }
74
75  public void setPrice(String price) {
76   this.price = price;
77  }
78
79  @Column(name = "descripton", length = 500)
80  public String getDescripton() {
81   return this.descripton;
82  }
83
84  public void setDescripton(String descripton) {
85   this.descripton = descripton;
86  }
87
88 }

测试代码：

HibernateTest.java

1 /**
2  *
3  */
4 package com.b510.examples;
5
6 import java.util.Set;
7
8 import org.hibernate.Session;
9 import org.hibernate.SessionFactory;
10 import org.hibernate.cfg.AnnotationConfiguration;
11 import org.hibernate.cfg.Configuration;
12
13 /**
14  *
15  * @author XHW
16  *
17  * @date 2011-7-20
18  *
19  */
20 public class HibernateTest {
21
22  public static void main(String[] args) {
23   HibernateTest test=new HibernateTest();
24   test.add();
25   test.find();
26  }
27  public void add(){
28  Configuration config=new AnnotationConfiguration();
29  config.configure();
30  SessionFactory sessionFactory=config.buildSessionFactory();
31  Session session=sessionFactory.getCurrentSession();
32  session.beginTransaction();
33  Category c=(Category)session.get(Category.class, 5);
34
35  Product p=new Product();
36  p.setName("计算机科学与技术");
37  p.setPrice("123");
38  p.setDescripton("计算机科学与技术,好啊，真是红啊");
39
40  p.setCategory(c);
41  c.getProducts().add(p);
42
43  session.save(p);
44  session.getTransaction().commit();
45  }
46
47
48  public void find(){
49   Configuration config=new AnnotationConfiguration();
50   config.configure();
51   SessionFactory sessionFactory=config.buildSessionFactory();
52   Session session=sessionFactory.getCurrentSession();
53   session.beginTransaction();
54   Category c=(Category)session.get(Category.class, 5);
55    System.out.println("id: "+c.getId()+"  name:"+c.getName());
56    Set<Product> p=c.getProducts();
57    for(Product product:p){
58     System.out.println("id:"+product.getId()+"  name:"+product.getName()+"  description:"+product.getDescripton());
59    }
60    session.getTransaction().commit();
61  }
62 }

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