hibernate--多对多单向（双向）关联

Teacher和Student来说明：

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Annotation注解：

teacher->student

Teacher.java:

package com.bean;

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

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.JoinColumns;
import javax.persistence.JoinTable;
import javax.persistence.ManyToMany;

@Entity
public class Teacher {
	private int id;
	private String name;
	private Set<Student> students = new HashSet<Student>();

	@ManyToMany
	@JoinTable(name="t_s",
              [email protected](name="TeacherID"),
              [email protected](name="stuendID")
			)
	public Set<Student> getStudents() {
		return students;
	}

	public void setStudents(Set<Student> students) {
		this.students = students;
	}

	@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;
	}

}

Student.java:

package com.bean;

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

@Entity
public class Student {
	private int id;
	private String name;

	@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;
	}

}

cfg.xml配置文件：

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-configuration PUBLIC
        "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
        "http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
   <session-factory>
     <property name="connection.driver_class">com.mysql.jdbc.Driver</property>    
     <property name="connection.url">jdbc:mysql://localhost:3306/user</property>     
     <property name="connection.username">root</property>   
     <property name="connection.password">root</property>
     
     <property name="dialect">org.hibernate.dialect.MySQLDialect</property>
     <property name="show_sql">true</property>
     
     <property name="hbm2ddl.auto">update</property>
     <property name="show_sql">true</property>
     <property name="format_sql">true</property>  
     
     <property name="current_session_context_class">thread</property>
       <mapping class="com.bean.Student"/>
     <mapping class="com.bean.Teacher"/>  
   </session-factory>
</hibernate-configuration>
        

XML配置:

Student.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>
  <class name = "com.bean.Student" table = "student" >

     <id name = "id" column="id">
       <generator class="native"/>
     </id>
     <property name="name" />
  </class>
</hibernate-mapping>        
 

Teacher.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>
  <class name = "com.bean.Teacher" table = "teacher" >

     <id name = "id" column="id">
       <generator class="native"/>
     </id>
     <property name="name" />
     <set name="students" table="t_s">
       <key column="teacher_Id"></key>
       <many-to-many class="com.bean.Student" column="student_Id"/>
     </set>
  </class>
</hibernate-mapping>        
 

cfg.xml中修改映射配置

   <mapping resource="com/bean/Student.hbm.xml"/>
    <mapping resource="com/bean/Teacher.hbm.xml"/>

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多对多双向关联：

1、xml配置：
Student.hbm.xml中添加配置即可：

       <set name="teachers" table="t_s">
       <key column="student_Id"></key>
       <many-to-many class="com.bean.Teacher" column="teacher_Id"/>
     </set>

2、Annotation配置：

在Student.java中添加：

	@ManyToMany(mappedBy="students")
	public Set<Teacher> getTeachers() {
		return teachers;
	}

	public void setTeachers(Set<Teacher> teachers) {
		this.teachers = teachers;
	}