Hibernate的组件（Component）映射

　　在学习Hibernate框架时碰到了许多实际的问题，比如一个Name是由FirstName和LastName组成，或者说一个Address是有Province，City，County和The detailed address组成，那么这么复杂的属性作为实际设计中是不应该出现在一个类里，那么组件映射就出现了

　　下面展示组件映射的实例，User对象中的Name属性

<?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.dao">

    <class name="User" table="User">
        <id name="id">
            <generator class="native" />
        </id>
 
        <component name="name">
            <property name="firstname" column="first_name"/>
            <property name="lastname" column="last_name" />
        </component>
        
        <property name="birthday" />

    </class>

</hibernate-mapping>

User.java代码

package com.dao;

import java.util.Date;

public class User {
    private int id;
    private Name name;
    private Date birthday;

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

    public int getId() {
        return id;
    }

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

    public Name getName() {
        return name;
    }

    public Date getBirthday() {
        return birthday;
    }

    public void setBirthday(Date birthday) {
        this.birthday = birthday;
    }
}

Name的代码

package com.dao;

public class Name {
    private String firstname;
    private String lastname;
    public String getFirstname() {
        return firstname;
    }
    public void setFirstname(String firstname) {
        this.firstname = firstname;
    }
    public String getLastname() {
        return lastname;
    }
    public void setLastname(String lastname) {
        this.lastname = lastname;
    }
}