hibernate之一对多双向关联

来源：互联网发布：java edu包编辑：程序博客网时间：2024/05/09 01:44

Annotation版本：

Group类：

package com.hibernate.model;import java.util.HashSet;import java.util.Set;import javax.persistence.Entity;import javax.persistence.GeneratedValue;import javax.persistence.Id;import javax.persistence.JoinColumn;import javax.persistence.OneToMany;import javax.persistence.OneToOne;import javax.persistence.Table;@Entity@Table(name="_Group")public class Group {private int id;private String name;private Set<User> users = new HashSet<User>();@Id@GeneratedValuepublic int getId() {return id;}public void setId(int id) {this.id = id;}public String getName() {return name;}@OneToMany(mappedBy="group")//双向的必须写上mappedBy,而且在数据库方面考虑，关联关系应该设计在多的一方，所以必须在OneToMany这方设mappedBypublic Set<User> getUsers() {return users;}public void setUsers(Set<User> users) {this.users = users;}public void setName(String name) {this.name = name;}}

User类：

package com.hibernate.model;import javax.persistence.Entity;import javax.persistence.GeneratedValue;import javax.persistence.Id;import javax.persistence.ManyToOne;import javax.persistence.Table;@Entity@Table(name="_User")public class User {private int id;private String name;private Group group;@ManyToOnepublic Group getGroup() {return group;}public void setGroup(Group group) {this.group = group;}@Id@GeneratedValuepublic int getId() {return id;}public void setId(int id) {this.id = id;}public String getName() {return name;}public void setName(String name) {this.name = name;}}

配置文件以及测试用例请参考以前的文章

xml版本：

Group类,User类同上

User.hbm.xml:

<?xml version="1.0"?><!DOCTYPE hibernate-mapping PUBLIC        "-//Hibernate/Hibernate Mapping DTD 3.0//EN"        "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd"><hibernate-mapping package="com.hibernate.model">    <class name="User" table="_User">    <id name="id">    <generator class="native"/>    </id>    <property name="name"></property>    <many-to-one name="group" column="groupId"></many-to-one>    </class></hibernate-mapping>

Group.hbm.xml:

<?xml version="1.0"?><!DOCTYPE hibernate-mapping PUBLIC        "-//Hibernate/Hibernate Mapping DTD 3.0//EN"        "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd"><hibernate-mapping package="com.hibernate.model">    <class name="Group" table="_Group">    <id name="id">    <generator class="native"/>    </id>    <property name="name"></property>    <set name="users">    <key column="groupId"></key>    <one-to-many class="com.hibernate.model.User"/>    </set>    </class></hibernate-mapping>

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