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",
joinColumns=@JoinColumn(name="TeacherID"),
inverseJoinColumns=@JoinColumn(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;
}