Hibernate基础之：树状结构遍历

一：TreeNode
树结构的一个节点，
主键是ID，具体内容是value
双向连接俩外键，分别是父节点pid，和子节点的集合children
[java]
@Entity
@Table(name="t_TreeNode")
public class TreeNode
{
    private int id;
    private String value;

    private TreeNode pid;//父节点id
    private Set<TreeNode> children = new HashSet<TreeNode>(); //子节点id

    @Id
    @GeneratedValue
    public int getId() {
        return id;
    }
    @OneToMany(cascade=(CascadeType.ALL),mappedBy="pid")//级联用ALL
    public Set<TreeNode> getChildren() {
        return children;
    }
    @ManyToOne
    @JoinColumn(name="p_Id")//指定外键名称，不指定的默认值是group_Id
    public TreeNode getPid() {
        return pid;
    }

二：存储
设置双向的关联
[java]
@Test
public void testIN() {
    Session session = HibernateUtil.getSessionFactory().getCurrentSession();
       session.beginTransaction();

       TreeNode root = new TreeNode();
       root.setValue("root");

       TreeNode top1 = new TreeNode();
       top1.setValue("top1");
       TreeNode top2 = new TreeNode();
       top2.setValue("top2");

       TreeNode sub1_1 = new TreeNode();
       sub1_1.setValue("sub1_1");
       TreeNode sub1_2 = new TreeNode();
       sub1_2.setValue("sub1_2");

       root.getChildren().add(top1);//正向
       root.getChildren().add(top2);
       top1.getChildren().add(sub1_1);
       top1.getChildren().add(sub1_2);

       sub1_1.setPid(top1);//反向
       sub1_2.setPid(top1);
       top1.setPid(root);
       top2.setPid(root);

       session.save(root);//因为设置级联，所以存储g时候也把u1和u2存上了。

       session.getTransaction().commit();
       HibernateUtil.getSessionFactory().close();
}

三：遍历
递归遍历
[java]
@Test
public void testOut() {

    Session session = HibernateUtil.getSessionFactory().getCurrentSession();
       session.beginTransaction();

       TreeNode node = (TreeNode)session.get(TreeNode.class, 1);
       print(node);


       session.getTransaction().commit();
       HibernateUtil.getSessionFactory().close();
}

public void print(TreeNode n)
{
       System.out.println(n.getValue());
       for(TreeNode child : n.getChildren())
       {
        print(child);
       }
}

补充：软件开发 , Java ,