Hibernate 映射一对一关联关系

Posted 2020-10-11 郑能量！

基于外键的方式：

　　附上代码：

　　

public class Manager {
    private Integer mgrId;
    private String mgrName;
    private Department department;

    public Integer getMgrId() {
        return mgrId;
    }

    public void setMgrId(Integer mgrId) {
        this.mgrId = mgrId;
    }

    public String getMgrName() {
        return mgrName;
    }

    public void setMgrName(String mgrName) {
        this.mgrName = mgrName;
    }

    public Department getDepartment() {
        return department;
    }

    public void setDepartment(Department department) {
        this.department = department;
    }

}

Manager 类

public class Department {
    private Integer deptId;
    private String deptName;
    private Manager manager;

    public Integer getDeptId() {
        return deptId;
    }

    public void setDeptId(Integer deptId) {
        this.deptId = deptId;
    }

    public String getDeptName() {
        return deptName;
    }

    public void setDeptName(String deptName) {
        this.deptName = deptName;
    }

    public Manager getManager() {
        return manager;
    }

    public void setManager(Manager manager) {
        this.manager = manager;
    }

}

Department 类

<hibernate-mapping>
    <class name="hibernate.one2one.foreign.Department" table="DEPARTMENTS">
        <id name="deptId" type="java.lang.Integer">
            <column name="DEPT_ID" />
            <generator class="native" />
        </id>
        <property name="deptName" type="java.lang.String">
            <column name="DEPT_NAME" />
        </property>
        <many-to-one name="manager" class="hibernate.one2one.foreign.Manager" unique="true" fetch="join">
            <column name="MGR_ID"></column>
        </many-to-one>
    </class>
</hibernate-mapping>

Department.hbm.xml

<hibernate-mapping>
    <class name="hibernate.one2one.foreign.Manager" table="MANAGER">
        <id name="mgrId" type="java.lang.Integer">
            <column name="MGR_ID" />
            <generator class="native" />
        </id>
        <property name="mgrName" type="java.lang.String">
            <column name="MGR_NAME" />
        </property>
        <one-to-one name="department"
            class="hibernate.one2one.foreign.Department"
            fetch="select"
            property-ref="manager">
        
        </one-to-one>
    </class>
</hibernate-mapping>

Manager.hbm.xml

　　其中 Department 使用 many-to-one 的方式映射 Manager，但是需要设置一个 unique 属性，设置为 true，使其只能指向一个 Manager

　　Manager 使用 one-to-one 的方式来映射 Department，注意需要设置一个 property-ref 属性，因为其默认关联的是 Department 表中的主键，需要设置其指向 Department 哪个属性，注意，这里设置的值是域对象中的值，不是数据表中的列名。