hibernate 一对多（多对一）双向

package com.bjsxt.hibernate;

import javax.persistence.Embedded;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.JoinColumns;
import javax.persistence.ManyToOne;
import javax.persistence.OneToOne;
import javax.persistence.PrimaryKeyJoinColumn;
import javax.persistence.Table;

@Entity
@Table(name="t_user")
public class User {
@Id
@GeneratedValue
private int id;
private String name;
@ManyToOne
private Group group;

public Group getGroup() {
return group;
}

public void setGroup(Group group) {
this.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;
}
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package com.bjsxt.hibernate;

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

import javax.persistence.Embedded;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.JoinColumns;
import javax.persistence.OneToMany;
import javax.persistence.OneToOne;
import javax.persistence.PrimaryKeyJoinColumn;
import javax.persistence.Table;

@Entity
@Table(name="t_group")
public class Group {
@Id
@GeneratedValue
private int id;

private String name;


@OneToMany(mappedBy = "group")
//@JoinColumn(name="groupId")
private Set<User> users = new HashSet<User>();

public int getId() {
return id;
}

public Set<User> getUsers() {
return users;
}
public void setUsers(Set<User> users) {
this.users = users;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}


}

}