Hibernate教程04_关系映射之一对一单向外键关联

本教程每节课都附带源码，强烈大家建议配合源码学习。
本节源码：http://download.youkuaiyun.com/detail/e421083458/5253705

关系映射(重要)

对象

这里的关系映射指的是对象之间的关系，并不是指数据库的关系，本章解决的问题是当对象之间处于
下列关系之一时，数据库表该如何映射，编程上该如何对待。

其实将问题简化就是：怎么写Annotation及增删改査CRUD怎么写

下面我们首先讲关系映射的一对一单向外键关联

Annotation: 在被约束表字段的get方法上加@0ne20ne @JoinColumn

@OneToOne            
@JoinColumn(name="wifeid") //指定生成的数据库字段名
public Wife getWife() {
    return wife;
}

xml: 在被约束表的xml配置文件中加<many-to-one unique

<class name="com.bjsxt.pojo.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>
unique="true"是保证生成的字段唯一,这样<many-to-one 也达到了一对一的效果

Annotation部分：

Husband.java

package com.bjsxt.hibernate;

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.OneToOne;
@Entity
public class Husband {
    private int id;
    private String name;
    private Wife wife;
    @Id
    @GeneratedValue
    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;
    }
    @OneToOne
    @JoinColumn(name="wifeId")
    public Wife getWife() {
        return wife;
    }
    public void setWife(Wife wife) {
        this.wife = wife;
    }
}

Wife.java

package com.bjsxt.hibernate;

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;

@Entity
public class Wife {
    private int id;
    private String name;
    @Id
    @GeneratedValue
    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;
    }
}

XML部分

Student.java

package com.bjsxt.hibernate;

public class Student {
    private int id;
    private String name;
    
    private int age;
    private String sex;
    private boolean 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;
    }
    public boolean isGood() {
        return good;
    }
    public void setGood(boolean good) {
        this.good = good;
    }
    
}

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;
    }
}

Student.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.Student" table="C_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>

测试源码：

package com.bjsxt.hiberante;


import java.util.Date;

import org.hibernate.Query;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.AnnotationConfiguration;
import org.hibernate.tool.hbm2ddl.SchemaExport;
import org.hibernate.Session;
import org.junit.AfterClass;
import org.junit.BeforeClass;
import org.junit.Test;

import com.bjsxt.hibernate.Husband;
import com.bjsxt.hibernate.StuIdCard;
import com.bjsxt.hibernate.Student;
import com.bjsxt.hibernate.Wife;


public class HibernateQLTest {
    private static SessionFactory sf;

    @BeforeClass
    public static void setUpBeforeClass() throws Exception {
        System.out.println("BeforeClass");
        sf = new AnnotationConfiguration().configure().buildSessionFactory();
    }

    @AfterClass
    public static void tearDownAfterClass() throws Exception {
        System.out.println("AfterClass");
        sf.close();
    }
    //
    @Test
    public void testSchemaExport(){
        new SchemaExport(new AnnotationConfiguration().configure()).create(false, true);        
    }
    @Test
    public void testOneTOOne_Wife(){
        Session session = sf.getCurrentSession();
        session.beginTransaction();
        Wife wife = new Wife();
        wife.setName("wife");
        Husband husband = new Husband();
        husband.setName("husband");
        husband.setWife(wife);
        session.save(wife);                            //先保存妻子
        session.save(husband);                        //再保存丈夫
        session.getTransaction().commit();
    }
    @Test
    public void testOneToOne_Stu(){
        Session session = sf.getCurrentSession();
        session.beginTransaction();
        Student stu = new Student();
        stu.setName("student");
        stu.setAge(20);
        stu.setGood(false);
        stu.setSex("man");
        StuIdCard idcard = new StuIdCard();
        idcard.setStudent(stu);
        idcard.setNum("什马卡？");
        session.save(stu);
        session.save(idcard);
        session.getTransaction().commit();
        
    }
    /*public static void main(String args[]){
        sf = new AnnotationConfiguration().configure().buildSessionFactory();
        
        Session session = sf.getCurrentSession();
        session.beginTransaction();
        Wife wife = new Wife();
        wife.setName("wife");
        Husband husband = new Husband();
        husband.setName("husband");
        husband.setWife(wife);
        session.save(husband);
        session.getTransaction().commit();
        
        sf.close();        
    }*/
}