hibernate笔记-016-树状结构

package com.hibernate.entity;import java.io.Serializable;import java.util.HashSet;import java.util.Set;import javax.persistence.CascadeType;import javax.persistence.Entity;import javax.persistence.GeneratedValue;import javax.persistence.Id;import javax.persistence.JoinColumn;import javax.persistence.ManyToOne;import javax.persistence.OneToMany;import javax.persistence.Table;import org.hibernate.annotations.GenericGenerator;// 树状结构@Entity@Table(name = "t_tree")public class Tree implements Serializable {private static final long serialVersionUID = 5234542236956544537L;@Id@GeneratedValue(generator = "tree_gen")@GenericGenerator(name = "tree_gen", strategy = "native")private int id;private String name;// 父节点@ManyToOne(optional = true)@JoinColumn(name = "parent_id")private Tree parent;// 子节点@OneToMany(mappedBy = "parent", cascade = CascadeType.ALL)private Set<Tree> children = new HashSet<Tree>();public Set<Tree> getChildren() {return children;}public int getId() {return id;}public String getName() {return name;}public Tree getParent() {return parent;}public void setChildren(Set<Tree> children) {this.children = children;}public void setId(int id) {this.id = id;}public void setName(String name) {this.name = name;}public void setParent(Tree parent) {this.parent = parent;}}