jpa单向多对一关联映射

package auth.model;

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

@Entity
@Table(name="class")
public class Room {
private int id;
private String name;
@Id
@GeneratedValue(strategy= GenerationType.AUTO)
@Column(name="id")
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
@Column(name="name")
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}

package auth.model;

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

@Entity
@Table(name="student")
public class Student {
private int id;
public int room_id;
private String name;
private Room room;
@GeneratedValue(strategy= GenerationType.AUTO)
@Id
@Column(name="id")
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
@Column(name="name")
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
@Column(name="room_id")
public int getRoom_id() {
return room_id;
}
public void setRoom_id(int room_id) {
this.room_id = room_id;
}
@ManyToOne
@JoinColumn(name = "room_id",insertable=false, updatable=false)
public Room getRoom() {
return room;
}
public void setRoom(Room room) {
this.room = room;
}

}

package auth.controller;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import com.alibaba.fastjson.JSONObject;

import auth.dao.ClassDao;
import auth.dao.StudentDao;
import auth.model.Room;
import auth.model.Student;

@Service
public class StudentController {
@Autowired
private ClassDao dao;
@Autowired
private StudentDao stuDao;
public void add(){
Room room=new Room();
room.setName("10班");
Student s=new Student();
dao.save(room);
s.setName("小李5");
s.setRoom(room);
stuDao.save(s);
}
public void query(){
Student s=stuDao.findOne(2);
System.out.println(JSONObject.toJSONString(s));

}
public void query1(){
Room s=dao.findOne(2);
System.out.println(JSONObject.toJSONString(s));

}

}

insert
into
class
(name)
values
(?)

auth.model.Room{name=11班, id=20}

insert
into
student
(name, room_id)
values
(?, ?)
2017-06-11 23:39:52,763 DEBUG [org.hibernate.id.IdentifierGeneratorHelper:94] - Natively generated identity: 24
2017-06-11 23:39:52,766 DEBUG [org.hibernate.engine.transaction.spi.AbstractTransactionImpl:175] - committing
2017-06-11 23:39:52,767 DEBUG [org.hibernate.event.internal.AbstractFlushingEventListener:149] - Processing flush-time cascades
2017-06-11 23:39:52,767 DEBUG [org.hibernate.event.internal.AbstractFlushingEventListener:189] - Dirty checking collections
2017-06-11 23:39:52,768 DEBUG [org.hibernate.event.internal.AbstractFlushingEventListener:123] - Flushed: 0 insertions, 0 updates, 0 deletions to 1 objects
2017-06-11 23:39:52,768 DEBUG [org.hibernate.event.internal.AbstractFlushingEventListener:130] - Flushed: 0 (re)creations, 0 updates, 0 removals to 0 collections
2017-06-11 23:39:52,772 DEBUG [org.hibernate.internal.util.EntityPrinter:114] - Listing entities:
2017-06-11 23:39:52,772 DEBUG [org.hibernate.internal.util.EntityPrinter:121] - auth.model.Student{room_id=0, name=小李6, id=24, room=auth.model.Room#20}
{"id":2,"name":"李明","room":{"id":1,"name":"12班"},"room_id":1}
{"id":2,"name":"24班"}