hibernate关系映射

java 代码

package com.test;

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

import com.test.domain.Student;
import com.test.domain.Teacher;

public class Test {
    public static void main(String[] args){

        Student student1 = new Student();
        Student student2 = new Student();

        Teacher teacher1 = new Teacher();
        Teacher teacher2 = new Teacher();


        student1.setStudentname("student1");
        student2.setStudentname("student2");

        teacher1.setTeachername("teachername1");
        teacher2.setTeachername("teachername2");

        Set set1 = new HashSet();
        set1.add(teacher1);
        set1.add(teacher2);


        student1.setTeachers(set1);
        student2.setTeachers(set1);

        OperatorDb od = new OperatorDb();
        od.saveUser(student1);
        od.saveUser(student2);

    }

}

输出结果为：
Hibernate: insert into hibernate.student (studentname) values (?)
Hibernate: insert into hibernate.teacher (teachername) values (?)
Hibernate: insert into hibernate.teacher (teachername) values (?)
Hibernate: insert into teacher_student (student_id, teacher_id) values (?, ?)
Hibernate: insert into teacher_student (student_id, teacher_id) values (?, ?)
Hibernate: insert into hibernate.student (studentname) values (?)
Hibernate: insert into teacher_student (student_id, teacher_id) values (?, ?)
Hibernate: insert into teacher_student (student_id, teacher_id) values (?, ?)

建表语句

sql 代码

--
-- Host: localhost    Database: hibernate
-- ------------------------------------------------------
-- Server version   5.0.24a-community-nt

/*!40101 SET @OLD_CHARACTER_SET_CLIENT=@@CHARACTER_SET_CLIENT */;
/*!40101 SET @OLD_CHARACTER_SET_RESULTS=@@CHARACTER_SET_RESULTS */;
/*!40101 SET @OLD_COLLATION_CONNECTION=@@COLLATION_CONNECTION */;
/*!40101 SET NAMES utf8 */;
/*!40103 SET @OLD_TIME_ZONE=@@TIME_ZONE */;
/*!40103 SET TIME_ZONE='+00:00' */;
/*!40014 SET @OLD_UNIQUE_CHECKS=@@UNIQUE_CHECKS, UNIQUE_CHECKS=0 */;
/*!40014 SET @OLD_FOREIGN_KEY_CHECKS=@@FOREIGN_KEY_CHECKS, FOREIGN_KEY_CHECKS=0 */;
/*!40101 SET @OLD_SQL_MODE=@@SQL_MODE, SQL_MODE='NO_AUTO_VALUE_ON_ZERO' */;
/*!40111 SET @OLD_SQL_NOTES=@@SQL_NOTES, SQL_NOTES=0 */;

--
-- Current Database: `hibernate`
--

CREATE DATABASE /*!32312 IF NOT EXISTS*/ `hibernate` /*!40100 DEFAULT CHARACTER SET utf8 */;

USE `hibernate`;

--
-- Table structure for table `detail`
--

DROP TABLE IF EXISTS `user`;
CREATE TABLE `user` (
  `id` int(11) NOT NULL auto_increment,
  `username` varchar(255)  NOT NULL,
  PRIMARY KEY  (`id`)
) ENGINE=MyISAM DEFAULT CHARSET=utf8;

DROP TABLE IF EXISTS `card`;
CREATE TABLE `card` (
  `userId` int(11) NOT NULL default '0',
  `cardNum` varchar(255)  NOT NULL,
  PRIMARY KEY  (`userId`)
) ENGINE=MyISAM DEFAULT CHARSET=utf8;

DROP TABLE IF EXISTS `item`;
CREATE TABLE `item` (
  `id` int(11) NOT NULL auto_increment,
  `userId` int(11) NOT NULL default '0',
  PRIMARY KEY  (`id`),
  foreign key(userId) references outTable(id) on delete cascade on update cascade
) ENGINE=MyISAM DEFAULT CHARSET=utf8;

1. one-to-one(用户和卡片)

user.hbm.xml

xml 代码

<!---->xml version="1.0" encoding="utf-8"?>
<!---->
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<!---->
<hibernate-mapping>
    <class name="yahaitt.bobo.domain.User" table="user">
        <id name="id" type="java.lang.Integer">
            <column name="id" />
            <generator class="native" />
        id>
        <property name="username" type="java.lang.String">
            <column name="username" not-null="true" />
        property>
        <one-to-one name="card" class="yahaitt.bobo.domain.Card" cascade="all">one-to-one>
    class>
hibernate-mapping>

 

Card.hbm.xml:

xml 代码

<!---->xml version="1.0" encoding="utf-8"?>
<!---->
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<!---->
<hibernate-mapping>
    <class name="yahaitt.bobo.domain.Card" table="card">
        <id name="userId" type="java.lang.Integer">
            <column name="userId" />
                <generator class="foreign" ><!---->
                    <param name="property">userparam>
                generator>
        id>
        <property name="cardNum" type="java.lang.String">
            <column name="cardNum" not-null="true" />
        property>
        <one-to-one name="user" class="yahaitt.bobo.domain.User" >

        one-to-one>
    class>
hibernate-mapping>

 

 

2. many-to-one (用户与Item)

注:两边都定义外键，而且不能像one-to-one里那样定义外键

如：这样定义是错误的：

xml 代码

<generator class="foreign" >
              <param name="property">userparam>
 generator>

 

user.hbm.xml:

xml 代码

<!---->xml version="1.0" encoding="utf-8"?>
<!---->
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<!---->
<hibernate-mapping>
    <class name="ttitfly.domain.User" table="user" >
        <id name="id" type="java.lang.Integer">
            <column name="id" />
            <generator class="native" />
        id>
        <property name="username" type="java.lang.String">
            <column name="username" not-null="true" />
        property>
        <set name="items" inverse="true" cascade="all" >
            <key><!---->
                <column name="userId" not-null="true" >
                column>
            key>
            <one-to-many class="ttitfly.domain.Item"/>
        set>
    class>
hibernate-mapping>

 

item.hbm.xml

xml 代码

<!---->xml version="1.0" encoding="utf-8"?>
<!---->
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<!---->
<hibernate-mapping>
    <class name="ttitfly.domain.Item" table="item" >
        <id name="id" type="java.lang.Integer">
            <column name="id" />
            <generator class="native" />
        id>
        <many-to-one name="user" class="ttitfly.domain.User">
            <!---->
            <column name="userId" not-null="true">column>
        many-to-one>
    class>
hibernate-mapping>

 

测试类:Test.java

java 代码

public class Test {

    public static void main(String[] args){


        User user = new User();
        user.setUsername("testonetomany");

        Item item1 = new Item();
        Item item2 = new Item();
        Set set = new HashSet();
        set.add(item1);
        set.add(item2);

        user.setItems(set);

        item2.setUser(user);
        item1.setUser(user);

        OperateDb operator  = new OperateDb();
        operator.saveUser(user);



    }

}

输出结果为：
Hibernate: insert into user (username) values (?)
Hibernate: insert into item (userId) values (?)
Hibernate: insert into item (userId) values (?)

当把user.hbm.xml里的

xml 代码

<set name="items" inverse="true" cascade="all" >

改为：

xml 代码

<set name="items" inverse="false" cascade="all" >

 

测试类输出的结果为：

java 代码

Hibernate: insert into user (username) values (?)
Hibernate: insert into item (userId) values (?)
Hibernate: insert into item (userId) values (?)
Hibernate: update item set userId=? where id=?
Hibernate: update item set userId=? where id=?

 

inverse的作用就可以很明显看出来了

 

3.many-to-many(学生和老师)

student.hbm.xml

xml 代码

<!---->xml version="1.0" encoding="utf-8"?>
<!---->
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<!---->
<hibernate-mapping>
    <class name="com.test.domain.Student" table="student" catalog="hibernate">
        <id name="id" type="java.lang.Integer">
            <column name="id" />
            <generator class="native" />
        id>
        <property name="studentname" type="java.lang.String">
            <column name="studentname" not-null="true" />
        property>
        <!---->
        <set name="teachers" table="teacher_student" inverse="false" cascade="all">
            <!---->
            <key column="student_id">key>
            <many-to-many class="com.test.domain.Teacher" column="teacher_id">many-to-many>
        set>
    class>
hibernate-mapping>

 

teacher.hbm.xml

java 代码

<!---->"1.0" encoding="utf-8"?>
<!---->"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<!---->
<hibernate-mapping></hibernate-mapping>
    <class name="com.test.domain.Teacher" table="teacher" catalog="hibernate">
        "id" type="java.lang.Integer">
            "id" />
            class="native" />

        "teachername" type="java.lang.String">
            "teachername" not-null="true" />

        "students" table="teacher_student" inverse="true">
            "teacher_id">
            "student_id" class="com.test.domain.Student">

    class>

 

测试类：

 

java 代码

package com.test;

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

import com.test.domain.Student;
import com.test.domain.Teacher;

public class Test {
    public static void main(String[] args){

        Student student1 = new Student();
        Student student2 = new Student();

        Teacher teacher1 = new Teacher();
        Teacher teacher2 = new Teacher();


        student1.setStudentname("student1");
        student2.setStudentname("student2");

        teacher1.setTeachername("teachername1");
        teacher2.setTeachername("teachername2");

        Set set1 = new HashSet();
        set1.add(teacher1);
        set1.add(teacher2);


        student1.setTeachers(set1);
        student2.setTeachers(set1);

        OperatorDb od = new OperatorDb();
        od.saveUser(student1);
        od.saveUser(student2);

    }

}
输出结果为：
Hibernate: insert into hibernate.student (studentname) values (?)
Hibernate: insert into hibernate.teacher (teachername) values (?)
Hibernate: insert into hibernate.teacher (teachername) values (?)
Hibernate: insert into teacher_student (student_id, teacher_id) values (?, ?)
Hibernate: insert into teacher_student (student_id, teacher_id) values (?, ?)
Hibernate: insert into hibernate.student (studentname) values (?)
Hibernate: insert into teacher_student (student_id, teacher_id) values (?, ?)
Hibernate: insert into teacher_student (student_id, teacher_id) values (?, ?)

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• 2007-10-12 22:11
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