一对多，多对一双向关联

阅读更多

表结构：

'CREATE TABLE `t_user` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `name` varchar(255) DEFAULT NULL,
  `group_id` int(11) DEFAULT NULL,
  PRIMARY KEY (`id`),
  KEY `FK_e5f24mh6aryt9hsy99oydps6g` (`group_id`),
  CONSTRAINT `FK_e5f24mh6aryt9hsy99oydps6g` FOREIGN KEY (`group_id`) REFERENCES `t_group` (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=2 DEFAULT CHARSET=utf8'

 

'CREATE TABLE `t_group` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `name` varchar(255) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=2 DEFAULT CHARSET=utf8'

 

Annotation方法：

Group类

package hibernate.entities;

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

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
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(strategy=GenerationType.AUTO)
	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")
	public Set getUsers() {
		return users;
	}
	public void setUsers(Set users) {
		this.users = users;
	}
	
	
}

 

User类

package hibernate.entities;

import javax.persistence.Column;
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;
	}
	
}

 

 xml方法：

Group类

package hibernate.entities;

import java.util.HashSet;
import java.util.Set;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.Table;

public class Group {

	private int id;
	private String name;
	private Set users = new HashSet();
	
	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;
	}
	public Set getUsers() {
		return users;
	}
	public void setUsers(Set users) {
		this.users = users;
	}
	
	
}

 

User类

package hibernate.entities;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.Table;

public class User {

	private int id;
	private String name;
	private Group group;
	

	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;
	}

	public Group getGroup() {
		return group;
	}
	public void setGroup(Group group) {
		this.group = group;
	}
	
}

 

Group.hbm.xml

 

User.hbm.xml