1、一对一单向外键关联

<?xml version=‘1.0‘ encoding=‘utf-8‘?>
<!DOCTYPE hibernate-configuration PUBLIC
        "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
        "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">

<hibernate-configuration>

    <session-factory>

        <!-- Database connection settings -->
        <!-- <property name="connection.driver_class">org.hsqldb.jdbcDriver</property>
                    <property name="connection.url">jdbc:hsqldb:hsql://localhost/TestDB</property> -->

        <property name="connection.driver_class">com.mysql.jdbc.Driver</property>
        <property name="connection.url">jdbc:mysql://localhost/test?useUnicode=true&amp;characterEncoding=UTF-8</property>
        <property name="connection.username">root</property>
        <property name="connection.password"></property>
        <property name="hbm2ddl.auto">update</property>
        <!-- SQL dialect -->
        <property name="dialect">
            org.hibernate.dialect.MySQL5InnoDBDialect
        </property>
        <property name="show_sql">true</property>
        <property name="format_sql">true</property>
         <mapping class="com.pt.hibernate.Husband" />
         <mapping class="com.pt.hibernate.Wife" />
    </session-factory>

</hibernate-configuration>

hibernate.cfg.xml

package com.pt.hibernate;

import java.util.Date;

import javax.annotation.Generated;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.OneToOne;

@Entity
public class Husband {
    int id;
    String name;
    Date bornTime;
    Wife myWife ;

    @OneToOne
    @JoinColumn(name="wifiId")    //指定外键字段名
    public Wife getMyWife() {
        return myWife;
    }

    public void setMyWife(Wife myWife) {
        this.myWife = myWife;
    }

    @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;
    }

    public Date getBornTime() {
        return bornTime;
    }

    public void setBornTime(Date bornTime) {
        this.bornTime = bornTime;
    }

}

Husband.java

package com.pt.hibernate;

import java.util.Date;

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

@Entity
public class Wife {
    int id;
    @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;
    }
    public Date getBornTime() {
        return bornTime;
    }
    public void setBornTime(Date bornTime) {
        this.bornTime = bornTime;
    }
    String name;
    Date bornTime;
}

Wife

import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;

public class Test {
    public static void main(String[] arges){
        Configuration cfg = new Configuration();
        SessionFactory factory = cfg.configure().buildSessionFactory();
    }
}

Test

2、一对一双向外键关联

　　两个相关联的实体类都写上@OneToOne即可，如果指定OneToOne的(mappedBy="")属性，这样就不会在两个表中都保留对方的ID，只会在其中一个表中保留对方的ID。只要有双向关联，该属性必设置。

package com.pt.hibernate;

import java.util.Date;

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

@Entity
public class Wife {
    int id;
    String name;
    Date bornTime;
    Husband myHusband ;
    @OneToOne(mappedBy="myWife")
    public Husband getMyHusband() {
        return myHusband;
    }
    public void setMyHusband(Husband myHusband) {
        this.myHusband = myHusband;
    }
    @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;
    }
    public Date getBornTime() {
        return bornTime;
    }
    public void setBornTime(Date bornTime) {
        this.bornTime = bornTime;
    }

}

Wife

3、多对一单向外键关联

　　多对一，数据库中的表现是在多的一方记录一的一方的ID，添加Son类，同时在配置文件中配置，Son类如下：

package com.pt.hibernate;

import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;

@Entity
public class Son {
    int id;
    String name;
    Husband myFather;

    @ManyToOne
    @JoinColumn(name="fatherId")
    public Husband getMyFather() {
        return myFather;
    }
    public void setMyFather(Husband myFather) {
        this.myFather = myFather;
    }
    @Id
    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;
    }
}

Son

4、多对一双向外键关联

　　在3、的基础上，修改Husband类，如下：

package com.pt.hibernate;

import java.util.Date;
import java.util.Set;

import javax.annotation.Generated;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.OneToMany;
import javax.persistence.OneToOne;

@Entity
public class Husband {
    int id;
    String name;
    Date bornTime;
    Wife myWife ;
    Set<Son> sons;

    @OneToMany(mappedBy="myFather")
    public Set<Son> getSons() {
        return sons;
    }

    public void setSons(Set<Son> sons) {
        this.sons = sons;
    }

    @OneToOne
    @JoinColumn(name="wifiId")    //指定外键字段名
    public Wife getMyWife() {
        return myWife;
    }

    public void setMyWife(Wife myWife) {
        this.myWife = myWife;
    }

    @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;
    }

    public Date getBornTime() {
        return bornTime;
    }

    public void setBornTime(Date bornTime) {
        this.bornTime = bornTime;
    }

}

Husband