Hibernate Annotation 多对一单向关联

Group类

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

@Entity  
@Table(name="t_group")  
public class Group {  

    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;  
    }  

}  

User类

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

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

}  

在User里面添加Group属性并加上注解@ManyToOne，这时候会在User表里生成一个group_id的外键，指向这个User所在的Group