hibernate多对多 关联映射(many-to-many)
在操作和性能方面都不太理想，所以多对多的映射使用较少，实际使用中最好转换成一对多的对象模型；
hibernate会为我们创建中间关联表，转换成两个一对多。
（1）一个最简单的例子就是学生选课的数据表了
（2）student.java
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public class course {
private integer id;
private string name;
private set<stucourse> stucourses;
//get/set方法
}
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（3）student.java
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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>
}
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（4）stucourse.java学生选课表
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package com.hsp.domain;
public class stucourse {
private integer id;
private student student;
private course course;
private integer grade;
//get/set方法
}
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（5）course.hbm.xml文件
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<?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>
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（6）student.hbm.xml文件
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<?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>
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（7）stucourse.hbm.xml文件
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<?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>
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（8）hibernate.cfg.xml文件
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<?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>
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总结
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原文链接：https://blog.csdn.net/huanglong1218/article/details/52313047