第八种：多对多单向关联
一、Annotation配置
每个Teacher可以有多个Student，每个Student可以被多个Teacher教
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1.Teacher.java
package com.zgy.hibernate.model;
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import java.util.HashSet;
import java.util.Set;
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import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.JoinTable;
import javax.persistence.ManyToMany;
import javax.persistence.Table;
@Entity
@Table(name="t_teacher")
public class Teacher {
private int id;
private String name;
private Set students = new HashSet();
@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;
}
@ManyToMany
@JoinTable(name="t_s" ,
joinColumns={@JoinColumn(name="teacher_id")},
inverseJoinColumns={@JoinColumn(name="student_id")}
)
public Set getStudents() {
return students;
}
public void setStudents(Set students) {
this.students = students;
}
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}
2.Student.java
package com.zgy.hibernate.model;
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import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.Table;
@Entity
@Table(name="t_student")
public class Student {
private int id;
private String name;
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@Id
@GeneratedValue
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
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public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
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}
3.测试，观察结果
Hibernate: create table t_s (teacher_id integer not null, student_id integer not null, primary key (teacher_id, student_id))
Hibernate: create table t_student (id integer not null auto_increment, name varchar(255), primary key (id))
Hibernate: create table t_teacher (id integer not null auto_increment, name varchar(255), primary key (id))
Hibernate: alter table t_s add constraint FK_3no0wm9bwtogr87t4gvd4t3x5 foreign key (student_id) references t_student (id)
Hibernate: alter table t_s add constraint FK_pj2fmd6skwfi7jm2avlo4n6mf foreign key (teacher_id) references t_teacher (id)
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二、Xml配置
1.Teacher.hbm.xml
"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
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2.Student.hbm.xml
"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
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3.观察结果
Hibernate: create table t_s (teacher_id integer not null, student_id integer not null, primary key (teacher_id, student_id))
Hibernate: create table t_student (id integer not null auto_increment, name varchar(255), primary key (id))
Hibernate: create table t_teacher (id integer not null auto_increment, name varchar(255), primary key (id))
Hibernate: alter table t_s add constraint FK_3no0wm9bwtogr87t4gvd4t3x5 foreign key (student_id) references t_student (id)
Hibernate: alter table t_s add constraint FK_pj2fmd6skwfi7jm2avlo4n6mf foreign key (teacher_id) references t_teacher (id)
第九种：多对多双向关联
一、Annotation配置
1.Teacher.java
package com.zgy.hibernate.model;
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import java.util.HashSet;
import java.util.Set;
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import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.p