hibernate之一对多双向关联

[java]代码库

package com.hibernate.model;import java.util.HashSet;import java.util.Set;import javax.persistence.Entity;import javax.persistence.GeneratedValue;import javax.persistence.Id;import javax.persistence.JoinColumn;import javax.persistence.OneToMany;import javax.persistence.OneToOne;import javax.persistence.Table;@Entity@Table(name=_Group)public class Group {private int id;private String name;private Set
 <user>
   users = new HashSet
  <user>
   ();@Id@GeneratedValuepublic int getId() { return id;}public void setId(int id) { this.id = id;}public String getName() { return name;}@OneToMany(mappedBy=group)//双向的必须写上mappedBy,而且在数据库方面考虑，关联关系应该设计在多的一方，所以必须在OneToMany这方设mappedBypublic Set
   <user>
     getUsers() { return users;}public void setUsers(Set
    <user>
      users) { this.users = users;}public void setName(String name) { this.name = name;}}
    </user>
   </user>
  </user>
 </user>//源代码片段来自云代码http://yuncode.net
			

package com.hibernate.model;import javax.persistence.Entity;import javax.persistence.GeneratedValue;import javax.persistence.Id;import javax.persistence.ManyToOne;import javax.persistence.Table;@Entity@Table(name=_User)public class User {private int id;private String name;private Group group;@ManyToOnepublic Group getGroup() {	return group;}public void setGroup(Group group) {	this.group = group;}@Id@GeneratedValuepublic 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;}}//源代码片段来自云代码http://yuncode.net