hibernate之一對多雙向關聯

Annotation版本：

Group類：

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
@GeneratedValue
public int getId() {
	return id;
}
public void setId(int id) {
	this.id = id;
}
public String getName() {
	return name;
}
@OneToMany(mappedBy="group")
//雙向的必須寫上mappedBy,而且在數據庫方面考慮，關聯關係應該設計在多的一方，所以必須在OneToMany這方設mappedBy
public Set<User> getUsers() {
	return users;
}
public void setUsers(Set<User> users) {
	this.users = users;
}
public void setName(String name) {
	this.name = name;
}

}

User類：

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;
@ManyToOne
public Group getGroup() {
	return group;
}
public void setGroup(Group group) {
	this.group = group;
}
@Id
@GeneratedValue
public 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;
}

}

配置文件以及測試用例請參考以前的文章

xml版本：

Group類,User類同上

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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