请问hibernate在一对多关系中在一的一端定义mappedby具体是什么意思呢，用crud举例一下呢，谢谢

比如department和employee是一对多关系的，我在department那边设置了mappedby，最后测试的结果只是不会生成第三张多余的表，其他没感觉什么，网上都说让多的这一段作为关系维护端，可是设置了mappedby后我还是可以在一的一端维护关系啊，那hibernate具体是怎么处理的呢，能不能从代码的角度再具体一点呢，谢谢

实体配置如下:

[code="java"]package com;

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

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

/**

Department entity.
@author MyEclipse Persistence Tools
*/
@Entity
@Table
public class Department implements java.io.Serializable {
// Fields
@Id
private Long depid;
private String depname;
@OneToMany(mappedBy="department")
private Set employees = new HashSet();
// Constructors
/** default constructor */
public Department() {
}
/** minimal constructor */
public Department(Long depid) {
this.depid = depid;
}
/** full constructor */
public Department(Long depid, String depname) {
this.depid = depid;
this.depname = depname;
}
// Property accessors
public Long getDepid() {
return this.depid;
}
public void setDepid(Long depid) {
this.depid = depid;
}
public String getDepname() {
return this.depname;
}
public void setDepname(String depname) {
this.depname = depname;
}
public Set getEmployees() {
return employees;
}
public void setEmployees(Set employees) {
this.employees = employees;
}

}[/code]
[code="java"]package com;

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

/**

Employee entity.
@author MyEclipse Persistence Tools */ @Entity @Table

public class Employee implements java.io.Serializable {

// Fields
@Id
private Long eeid;
private String eename;
@Column(name="dep_id",insertable=false,updatable=false)
private Long depId;
@ManyToOne(cascade=CascadeType.ALL)
@JoinColumn(name="dep_id")
private Department department;
// Constructors

/** default constructor */
public Employee() {
}

/** minimal constructor */
public Employee(Long eeid) {
    this.eeid = eeid;
}

/** full constructor */
public Employee(Long eeid, String eename, Long depId) {
    this.eeid = eeid;
    this.eename = eename;
    this.depId = depId;
}

// Property accessors

public Long getEeid() {
    return this.eeid;
}

public void setEeid(Long eeid) {
    this.eeid = eeid;
}

public String getEename() {
    return this.eename;
}

public void setEename(String eename) {
    this.eename = eename;
}

public Long getDepId() {
    return this.depId;
}

public void setDepId(Long depId) {
    this.depId = depId;
}

public Department getDepartment() {
    return department;
}

public void setDepartment(Department department) {
    this.department = department;
}

}[/code]

:( 请lz还是把自己的源码贴出来，让大家分析下

mapped用于指定在双向关系中两个实体中被哪个实体是被关联处理的.

在你的department和employee的一对多关系中,当你指定department中的mappedBy后,你的关系只能被employee来主动维护.也就是employee级联的处理department.

一对多单向关联(多方维护):
[code="java"]
package com;

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

import org.hibernate.Session;

created time:上午11:44:11
creator: Tian Zhichao (chinoistzc@gmail.com)
*
*/
public class Test {
/**
- main()
- 2010-4-5,上午11:44:11
  */
  public static void main(String[] args) {
  // TODO Auto-generated method stub
  Session session = HibernateSessionFactory.getSession();
  session.beginTransaction();
  Department dep = new Department();
  dep.setDepid(123L);
  dep.setDepname("dep name");
  Employee ee1 = new Employee();
  Employee ee2 = new Employee();
  ee1.setEeid(1L);
  ee1.setDepartment(dep);
  ee2.setEeid(2L);
  ee2.setDepartment(dep);
  Set employees = new HashSet();
  employees.add(ee1);
  employees.add(ee2);
  dep.setEmployees(employees);
  session.save(ee1);
  session.save(ee2);
  session.getTransaction().commit();
  System.out.println("-----------------用一端来保存时....");
  session.beginTransaction();
  Department dep2 = new Department();
  dep2.setDepid(100L);
  dep2.setEmployees(employees);
  session.save(dep2);
  session.getTransaction().commit();
  session.close();
  }

}

[/code]
Hibernate打印输出的:
[code="java"]log4j:WARN No appenders could be found for logger (org.hibernate.cfg.annotations.Version).
log4j:WARN Please initialize the log4j system properly.
Hibernate:
select
department_.depid,
department_.depname as depname1_
from
Department department_
where
department_.depid=?
Hibernate:
insert
into
Department
(depname, depid)
values
(?, ?)
Hibernate:
insert
into
Employee
(dep_id, eename, eeid)
values
(?, ?, ?)
Hibernate:
insert
into
Employee
(dep_id, eename, eeid)
values
(?, ?, ?)
-----------------用一端来保存时....
Hibernate:
insert
into
Department
(depname, depid)
values
(?, ?)
[/code]

下面这个显示了只department,做为被维护端时,如果保存它,Hibernate会只保存它自已.
[code="java"]
package com;

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

import org.hibernate.Session;

created time:上午11:44:11
creator: Tian Zhichao (chinoistzc@gmail.com)
*
*/
public class Test {
/**
- main()
- 2010-4-5,上午11:44:11
  */
  public static void main(String[] args) {
  // TODO Auto-generated method stub
  Session session = HibernateSessionFactory.getSession();
  session.beginTransaction();
  Department dep = new Department();
  dep.setDepid(123L);
  dep.setDepname("dep name");
  Employee ee1 = new Employee();
  Employee ee2 = new Employee();
  ee1.setEeid(1L);
  ee1.setDepartment(dep);
  ee2.setEeid(2L);
  ee2.setDepartment(dep);
  Set employees = new HashSet();
  employees.add(ee1);
  employees.add(ee2);
  dep.setEmployees(employees);
  session.save(dep);
  session.getTransaction().commit();
  session.close();
  }

}
[/code]
[code="java"]log4j:WARN No appenders could be found for logger (org.hibernate.cfg.annotations.Version).
log4j:WARN Please initialize the log4j system properly.
Hibernate:
insert
into
Department
(depname, depid)
values
(?, ?)
[/code]

[size=x-large][color=red]希望对你有帮助..[/color][/size]