iii、观察生成的sql
Hibernate: create table t_group (id integer not null auto_increment, name varchar(255), primary key (id)) Hibernate: create table t_user (id integer not null auto_increment, name varchar(255), groupId integer, primary key (id)) Hibernate: alter table t_user add constraint FK_7ktm6l2qkykpqrf6oq01ys8wy foreign key (groupId) references t_group (id)
二、Xml配置
i、Group.hbm.xml
ii、User.hbm.xml
iii、观察生成的sql语句
Hibernate: create table t_group (id integer not null auto_increment, name varchar(255), primary key (id)) Hibernate: create table t_user (id integer not null auto_increment, name varchar(255), groupId integer, primary key (id)) Hibernate: alter table t_user add constraint FK_7ktm6l2qkykpqrf6oq01ys8wy foreign key (groupId) references t_group (id)
C、一对多，多对一双向关联
一、Annotation配置
1.Group.java
package com.zgy.hibernate.model;
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.OneToMany;
import javax.persistence.Table;
@Entity
@Table(name="t_group")
public class Group {
private int id;
private String name;
private Set users = 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;
}
@OneToMany(mappedBy="group")
@JoinColumn(name="groupId")
public Set getUsers() {
return users;
}
public void setUsers(Set users) {
this.users = users;
}
}
2.User.java
package com.zgy.hibernate.model;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.Table;
@Entity
@Table(name="t_user")
public class User {
private int id;
private String name;
private Group group;
@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;
}
@ManyToOne
public Group getGroup() {
return group;
}
public void setGroup(Group group) {
this.group = group;
}
}
3.查看生成的sql语句
Hibernate: create table t_group (id integer not null auto_increment, name varchar(255), primary key (id)) Hibernate: create table t_user (id integer not null auto_increment, name varchar(255), groupId integer, primary key (id)) Hibernate: alter table t_user add constraint FK_7ktm6l2qkykpqrf6oq01ys8wy foreign key (groupId) references t_group (id)
二、Xml配置
1.Group.hbm.xml
2.User.hbm.xml