Hibernate中的一对一多映射和一对一映射的创建

1.首先创建Main类，它里面包含了两种映射，和Second的一对多以及和Forrum的一对一

package com.ch.entity;

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

public class Main {

    private int id;        //主键
    private String main_title;    //标题
    private String main_content;    //内容
    private Date   main_createtime;    //发帖的时间
    private String main_createuser; //发帖的用户
    private Forum forum;            //主贴的信息
    private Set<Second> seconds=new HashSet<Second>();            //跟帖
    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    public String getMain_title() {
        return main_title;
    }
    public void setMain_title(String main_title) {
        this.main_title = main_title;
    }
    public String getMain_content() {
        return main_content;
    }
    public void setMain_content(String main_content) {
        this.main_content = main_content;
    }
    public Date getMain_createtime() {
        return main_createtime;
    }
    public void setMain_createtime(Date main_createtime) {
        this.main_createtime = main_createtime;
    }
    public String getMain_createuser() {
        return main_createuser;
    }
    public void setMain_createuser(String main_createuser) {
        this.main_createuser = main_createuser;
    }
    public Forum getForum() {
        return forum;
    }
    public void setForum(Forum forum) {
        this.forum = forum;
    }
    public Set<Second> getSeconds() {
        return seconds;
    }
    public void setSeconds(Set<Second> seconds) {
        this.seconds = seconds;
    }
    
    
}

2.创建映射文件Main.hbm.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE hibernate-mapping PUBLIC 
    "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
    "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">

<hibernate-mapping package="com.ch.entity">

    <class name="Main" table="my_main">
        <id name="id" column="main_id">
            <generator class="native"></generator>
        </id>
        <property name="main_title"></property>
        <property name="main_content"></property>
        <property name="main_createtime"></property>
        <property name="main_createuser"></property>
        <!-- 一对一，没有外键-->
        <one-to-one  name="forum" class="Forum" cascade="all"></one-to-one>
         
        <!-- 多对一，没有外键-->
        <set name="seconds" cascade="all" >
            <key column="main_id"></key>
            <one-to-many class="Second"/>
        </set>
          
    </class>

</hibernate-mapping>

3.创建Forum类

package com.ch.entity;

import java.util.Date;

public class Forum {

    private int id;   //主键
    private Main main;     //所属的帖子
    private int info_reply;        //回复的数量
    private int info_see;        //查看的数量
    private String info_lastuser;    //最后回复的用户
    private Date info_lastime;        //最后回复的时间
    private Dictionary dict;        //板块
    private int dict_id;            //自己设置的板块id
    private String main_id;            //自己设置的外键
    
    
    
    public String getMain_id() {
        return main_id;
    }
    public void setMain_id(String main_id) {
        this.main_id = main_id;
    }
    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    public int getDict_id() {
        return dict_id;
    }
    public void setDict_id(int dict_id) {
        this.dict_id = dict_id;
    }
    public Main getMain() {
        return main;
    }
    public void setMain(Main main) {
        this.main = main;
    }
    public int getInfo_reply() {
        return info_reply;
    }
    public void setInfo_reply(int info_reply) {
        this.info_reply = info_reply;
    }
    public int getInfo_see() {
        return info_see;
    }
    public void setInfo_see(int info_see) {
        this.info_see = info_see;
    }
    public String getInfo_lastuser() {
        return info_lastuser;
    }
    public void setInfo_lastuser(String info_lastuser) {
        this.info_lastuser = info_lastuser;
    }
    public Date getInfo_lastime() {
        return info_lastime;
    }
    public void setInfo_lastime(Date info_lastime) {
        this.info_lastime = info_lastime;
    }
    public Dictionary getDict() {
        return dict;
    }
    public void setDict(Dictionary dict) {
        this.dict = dict;
    }
}

4.创建一对一的唯一外键约束-------Forum.hbm.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE hibernate-mapping PUBLIC 
    "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
    "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">

<hibernate-mapping package="com.ch.entity">
    <class name="Forum" table="forum_info">
        <id name="id" column="info_id">
            <generator class="native"></generator>
        </id>
        <property name="info_reply"></property>
        <property name="info_see"></property>
        <property name="info_lastuser"></property>
        <property name="info_lastime"></property>
        <!-- 一对一映射，有外键方
            unique="true"   给外键字段添加唯一约束
          -->
         <many-to-one   name="main" unique="true" column="main_id" class="Main" cascade="save-update"></many-to-one>
         <!-- 多对一映射，由外建方 -->
         <many-to-one name="dict" class="Dictionary" column="dict_id"  ></many-to-one>
    </class>

</hibernate-mapping>

5.创建Second类

package com.ch.entity;

import java.util.Date;

public class Second {

    private int id;    //主键
    private Main main;                //主贴
    private  String sec_content;    //内容
    private Date sec_createtime;    //发帖时间
    private  String sec_createuser;    //发帖人

    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    public Main getMain() {
        return main;
    }
    public void setMain(Main main) {
        this.main = main;
    }
    public String getSec_content() {
        return sec_content;
    }
    public void setSec_content(String sec_content) {
        this.sec_content = sec_content;
    }
    public Date getSec_createtime() {
        return sec_createtime;
    }
    public void setSec_createtime(Date sec_createtime) {
        this.sec_createtime = sec_createtime;
    }
    public String getSec_createuser() {
        return sec_createuser;
    }
    public void setSec_createuser(String sec_createuser) {
        this.sec_createuser = sec_createuser;
    }
    
    
}

6.创建Second的映射文件Second.hbm.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE hibernate-mapping PUBLIC 
    "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
    "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">

<hibernate-mapping package="com.ch.entity">

    <class name="Second" table="my_second">
        <id name="id" column="sec_id">
            <generator class="native"></generator>
        </id>
        <property name="sec_content"></property>
        <property name="sec_createtime"></property>
        <property name="sec_createuser"></property>
        <!-- 多对一的映射 由外键方 -->
        <many-to-one name="main"  column="main_id" class="Main" />
    </class>

</hibernate-mapping>