8.1.8 连接字符串

首先：数据表user如下：

create database person;

use person

CREATE TABLE USER (
    ID CHAR(32) NOT NULL,
    DISCRIMINATOR_TYPE VARCHAR(255) NOT NULL,
    NAME VARCHAR(16) NOT NULL,
    PASSWORD VARCHAR(16) NOT NULL,
    POWERUSER_LEVEL INTEGER,
    POWER_OTHER VARCHAR(255),
    GUEST_OTHER VARCHAR(255),
    PRIMARY KEY(ID)
)

其次：User类是PowerUser类、GuestUser类的父类，代码如下：

//User类代码
package com.cn.gz.factory;

public class User ...{
    private String id;
    private String name;
    private String password;

    public String getId() ...{
        return id;
    }

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

    public String getName() ...{
        return name;
    }

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

    public String getPassword() ...{
        return password;
    }

    public void setPassword(String password) ...{
        this.password = password;
    }
}

//PowerUser类代码
package com.cn.gz.factory;

public class PowerUser extends User ...{
    private int level;
    private String otherOfPower;

    public int getLevel() ...{
        return level;
    }

    public void setLevel(int level) ...{
        this.level = level;
    }

    public String getOtherOfPower() ...{
        return otherOfPower;
    }

    public void setOtherOfPower(String otherOfPower) ...{
        this.otherOfPower = otherOfPower;
    }
}

//GuestUser类代码
package com.cn.gz.factory;

public class GuestUser extends User ...{
    private String otherOfGuest;

    public String getOtherOfGuest() ...{
        return otherOfGuest;
    }

    public void setOtherOfGuest(String otherOfGuest) ...{
        this.otherOfGuest = otherOfGuest;
    }

}

再次：配置映射文件User.hbm.xml，如下：

<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<!-- 
    Mapping file autogenerated by MyEclipse Persistence Tools
-->
<hibernate-mapping>
    <class name="com.cn.gz.factory.User" table="user" catalog="person" discriminator-value="ParentUser">
        <id name="id" type="string" unsaved-value="null">
            <column name="ID" length="32" />
            <generator class="uuid.hex" />
        </id>
        
        <discriminator column="DISCRIMINATOR_TYPE" type="string" />
        
        <property name="name" type="string">
            <column name="NAME" length="16" not-null="true" />
        </property>
        
        <property name="password" type="string">
            <column name="PASSWORD" length="16" not-null="true" />
        </property>
        
        <subclass name="com.cn.gz.factory.PowerUser" discriminator-value="POWER">
            <property name="level" type="integer" column="POWERUSER_LEVEL" />
            <property name="otherOfPower" type="string" column="POWER_OTHER" />
        </subclass>
        
        <subclass name="com.cn.gz.factory.GuestUser" discriminator-value="GUEST">
            <property name="otherOfGuest" type="string" column="GUEST_OTHER" />
        </subclass>
    </class>
</hibernate-mapping>

总结：一个表的继承映射是通过一个discriminator标识来识别的。父类与子类都要加上discriminator-value属性，用subclass标签指定子类，name为子类类名。