数据库中的素面树 [英] Primefaces tree from database

问题描述

我有以下实体类:

@Entity
@Table(name = "THE_TREE", catalog = "", schema = "dbo")
public class TheTree implements Serializable {
private static final long serialVersionUID = 1L;
@Id
@Column(name = "ID", nullable = false)
@GeneratedValue(strategy = GenerationType.AUTO)
private Long id;

@Column(name = "NODE_NAME")
private String name;

@Column(name = "LEVEL")
private int level;

@OneToMany    
@JoinColumn(name="PARENTID")    
public List<TheTree > children = new LinkedList<TheTree >();

我想将其表示到素数树中，但我做对了.primefaces 网站中给出的示例具有预定义深度的静态节点，其中我需要未知深度的节点并从数据库中填充.我在这里看到了各种帖子，但对我来说什么都不清楚.在这篇帖子中，作者似乎问了同样的问题，但答案是以某种方式与问题无关.任何解决方案将不胜感激.

I would like to represent this into primefaces tree, but I cant get it right. The example given in primefaces website has static nodes with predefined depth, where I need nodes with unknown depth and to be filled from database. I have seen various posts here but nothing is clear to me. In this post it seems the author has asked the same question but the answer is not relative to the question somehow. Any solution would be appreciated.

推荐答案

你必须创建一个递归函数来制作树.这就是我要做的:

You have to create a recursive function to make the tree. This is how I would do it:

@ManagedBean
@ViewScoped
public class TreeMBean {

    private TreeNode rootNode;

     @PostConstruct
     public void init() {
         TheTree root = new TheTree(); // instead get root object from database 
         rootNode = newNodeWithChildren(root, null);
     }

     /**
      *  recursive function that returns a new node with its children
     */
     public TreeNode newNodeWithChildren(TheTree ttParent, TreeNode parent){
          TreeNode newNode= new DefaultTreeNode(ttParent, parent);
          for (TheTree tt : ttParent.getChildren()){
               TreeNode newNode2= newNodeWithChildren(tt, newNode);
          }
          return newNode;
     }

     public TreeNode getRootNode() {
         return rootNode;
     }

     public void setRootNode(TreeNode node) {
         rootNode = node;
     }

 }

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