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Hibernate实现many-to-many的映射关系

2024-07-26 12:37:31   222人阅读


（1）一个最简单的例子就是学生选课的数据表了


（2）Student.java

public class Course {
	private Integer id;
	private String name;
	private Set<StuCourse> stuCourses;
	//get/set方法
}

（3）Student.java

public class Student {
	private Integer id;
	private String name;
	private Set<StuCourse> stuCourses;
	<span style="font-family: Arial, Helvetica, sans-serif;">//get/set方法</span>
}
（4）StuCourse.java学生选课表

package com.hsp.domain;

public class StuCourse {
	private Integer id;
	private Student student;
	private Course course;
	private Integer grade;
	//get/set方法
	
}

（5）Course.hbm.xml文件

<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping package="com.hsp.domain">
	<class name="Course">
		<id name="id" type="java.lang.Integer">
			<generator class="sequence">
				<param name="sequence">course_seq</param>
			</generator>
		</id>
		<property name="name" type="java.lang.String">
			<column name="name" length="64" />
		</property>
		<!-- 配置one-to-many 表示一门课程可以对应多个选课记录 -->
		<set name="stuCourses">
			<key column="course_id" />
			<one-to-many class="StuCourse" />
		</set>
	</class>
</hibernate-mapping>

（6）Student.hbm.xml文件

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

<hibernate-mapping package="com.hsp.domain">
	<class name="Student">
		<id name="id" type="java.lang.Integer">
			<generator class="sequence">
				<param name="sequence">stu_seq</param>
			</generator>
		</id>
		<property name="name" type="java.lang.String">
			<column name="name" length="64" />
		</property>
	 	<!-- 这里我们配置了one-to-many 一个学生可以对应多个选课记录 -->
		<set name="stuCourses">
			<key column="student_id" /> <!-- 这里的column是外键 -->
			<one-to-many class="StuCourse" /> <!-- many所对应的表 -->
		</set>
	</class>
</hibernate-mapping>

（7）StuCourse.hbm.xml文件

<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping package="com.hsp.domain">
	<class name="StuCourse">
		<id name="id" type="java.lang.Integer">
			<generator class="sequence">
				<param name="sequence">stucourse_seq</param>
			</generator>
		</id>
		<property name="grade" type="java.lang.Integer">
			<column name="grade" length="3" />
		</property>
		<many-to-one name="course" column="course_id" />
		<many-to-one name="student" column="student_id" />
	</class>
</hibernate-mapping>

（8）hibernate.cfg.xml文件

<?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">

<!-- Generated by MyEclipse Hibernate Tools. -->
<hibernate-configuration>

	<session-factory>
		<property name="connection.username">root</property>
		<property name="connection.url">
			jdbc:oracle:thin:@127.0.0.1:1521:OracleDB
		</property>
		<property name="dialect">
			org.hibernate.dialect.Oracle9Dialect
		</property>
		<property name="connection.password">root</property>
		<property name="connection.driver_class">
			oracle.jdbc.driver.OracleDriver
		</property>
		<property name="show_sql">true</property>
		<!-- 配置让hibernate自动创建关系模型(表) -->
		<property name="hbm2ddl.auto">update</property>
		<mapping resource="com/hsp/domain/Course.hbm.xml" />
		<mapping resource="com/hsp/domain/StuCourse.hbm.xml" />
		<mapping resource="com/hsp/domain/Student.hbm.xml" />

	</session-factory>

</hibernate-configuration>






Hibernate实现many-to-many的映射关系


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