Hibernate ORM Component

　　Hibernate提倡在建模时，进行细粒度的控制。这个抽象的概念可以这样理解，一般在进行Hibernate持久化对象建模时，一个对象对应一个配置文件，在配置文件中的属性都有这样一个对象中的属性对应。试想如果一个对象的属性有十几二十个，那么这个对象显然就会变得很大，尤其是getter和setter方法。这样显然会增加对象的复杂度，使得对象变得难以理解。那这时该怎么办呢。Hibernate为我们提供了这样一个途径。那就是利用Component。即这么多属性中必然有些属性是在概念上相近的，如一个Person对象中有这样三个属性,firstname,middlename,lastname，这三个属性都和名字有关，所以可以提成一个Name对象作为Person的Component。这就是Hibernate提倡的细粒度控制了。这样对象就变得易于理解，更为接近现实中的情况，使项目变得易于扩展和维护。那代码上具体如何实现呢。

 

　　１.FullName.java

 

package com.template.model.person;

/**
 * Created by IntelliJ IDEA.
 * User: ZhongGang
 * Date: 11-7-21
 * Time: 下午8:22
 * To change this template use File | Settings | File Templates.
 */
public class FullName {
    private String firstName;
    private String middleName;
    private String lastName;

    public FullName() {
    }
}

 

　　２.Name.java

 

package com.template.model.person;

/**
 * Created by IntelliJ IDEA.
 * User:ZhongGang
 * Date: 11-7-21
 * Time: 下午8:22
 * To change this template use File | Settings | File Templates.
 */
public class Name {
    private FullName fullName;
    private String nickName;

    public Name() {
    }
}

 

 

　　３.Address.java

 

package com.template.model.person;

/**
 * Created by IntelliJ IDEA.
 * User: Zhong Gang
 * Date: 11-7-21
 * Time: 下午8:24
 * To change this template use File | Settings | File Templates.
 */
public class Address {
    private String street;
    private String city;
    private String country;

    public Address() {
    }
}

 

 

　　４.Human.java

 

package com.template.model.person;

/**
 * Created by IntelliJ IDEA.
 * User: Zhong Gang
 * Date: 11-7-21
 * Time: 下午8:21
 * To change this template use File | Settings | File Templates.
 */
public class Human extends BasicDomain {
    private Name name;
    private Address address;

    public Human() {
    }
}

 

 

　　５.Human.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 default-access="field">

    <class name="com.template.model.person.Human" table="human">
        <id name="id" column="id" type="java.lang.Integer">
            <generator class="native"/>
        </id>
        <property name="active" column="active" type="java.lang.Boolean"/>
        <component name="name" class="com.template.model.person.Name">
            <component name="fullName" class="com.template.model.person.FullName">
                <property name="firstName" column="firstname" type="java.lang.String"/>
                <property name="middleName" column="middlename" type="java.lang.String"/>
                <property name="lastName" column="lastname" type="java.lang.String"/>
            </component>
            <property name="nickName" column="nickname" type="java.lang.String"/>
        </component>
        <component name="address" class="com.template.model.person.Address">
            <property name="street" column="street" type="java.lang.String"/>
            <property name="country" column="country" type="java.lang.String"/>
            <property name="city" column="city" type="java.lang.String"/>
        </component>
    </class>

</hibernate-mapping>

 

　　从Name和FullName可以看出，Hibernate支持多层的Component嵌套。

 

　　如果想实现从Name知道是哪个Human，应该怎么办呢？看下面的代码。只须作稍许的修改。

 

　　Name.java

 

package com.template.model.person;

/**
 * Created by IntelliJ IDEA.
 * User: Zhong Gang
 * Date: 11-7-21
 * Time: 下午8:22
 * To change this template use File | Settings | File Templates.
 */
public class Name {
    private FullName fullName;
    private String nickName;

    private Human human;

    public Name() {
    }

    public Human getHuman() {
        return human;
    }

    public void setHuman(Human human) {
        this.human = human;
    }
}

 

 

　　Human.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 default-access="field">

    <class name="com.template.model.person.Human" table="human">
        <id name="id" column="id" type="java.lang.Integer">
            <generator class="native"/>
        </id>
        <property name="active" column="active" type="java.lang.Boolean"/>
        <component name="name" class="com.template.model.person.Name">
            <parent name="human"/>
            <component name="fullName" class="com.template.model.person.FullName">
                <property name="firstName" column="firstname" type="java.lang.String"/>
                <property name="middleName" column="middlename" type="java.lang.String"/>
                <property name="lastName" column="lastname" type="java.lang.String"/>
            </component>
            <property name="nickName" column="nickname" type="java.lang.String"/>
        </component>
        <component name="address" class="com.template.model.person.Address">
            <property name="street" column="street" type="java.lang.String"/>
            <property name="country" column="country" type="java.lang.String"/>
            <property name="city" column="city" type="java.lang.String"/>
        </component>
    </class>

</hibernate-mapping>

评论

3 楼 hcchanqing 2012-11-13  

Wind_ZhongGang 写道

hcchanqing 写道

真心没看明白。。。

哪不明白？

Component这个。可以留个QQ吗？

2 楼 Wind_ZhongGang 2012-11-12  

hcchanqing 写道

真心没看明白。。。

哪不明白？

1 楼 hcchanqing 2012-11-12  

真心没看明白。。。