036：一对一单向外键关联（在xml中）

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可以用Student和StuIdCard来举例：

1、Student.java类：

package com.bjsxt.hibernate;public class Student {private int id;private String name;private int age;private String sex;private boolean good;public boolean isGood() {return good;}public void setGood(boolean good) {this.good = good;}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;}public int getAge() {return age;}public void setAge(int age) {this.age = age;}public String getSex() {return sex;}public void setSex(String sex) {this.sex = sex;}}

2.Student.hbm.xml中：

<?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><class name="com.bjsxt.hibernate.Student" dynamic-update="true"><id name="id"><generator class="native"></generator></id><property name="name"></property><property name="age" /><property name="sex" /><property name="good" type="yes_no"></property>    </class></hibernate-mapping>

3、建StuIdCard.java

package com.bjsxt.hibernate;public class StuIdCard {private int id;private String num;private Student student;public int getId() {return id;}public void setId(int id) {this.id = id;}public String getNum() {return num;}public void setNum(String num) {this.num = num;}public Student getStudent() {return student;}public void setStudent(Student student) {this.student = student;}}

4、建相应的xml文件：StuIdCard.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><class name="com.bjsxt.hibernate.StuIdCard"><id name="id"><generator class="native"></generator></id><property name="num"/><many-to-one name="student" column="studentId" unique="true"></many-to-one>    </class></hibernate-mapping>

5、<many-to-one name="student" column="studentId" unique="true"></many-to-one>

这句话意思为多对一，如果站在StuIdCard的方面，many-to-one意味多个学生证对应一个学生，因不是一对一，所以后面加了个unique="true"即保证IdCard的唯一，这样就变成一对一的单向关联了，column="studentId"即用column来定义用哪个字段作为外键关联的字段。

6、在hibernate.cfg.xml中加入：

         <mapping resource="com/bjsxt/hibernate/Student.hbm.xml"/>         <mapping resource="com/bjsxt/hibernate/StuIdCard.hbm.xml"/>

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