如何创建动态树？

我在使用primefaces树实现实现动态树结构时遇到了一些麻烦。 在primeface提供的展示中，代码的结构如下所示。 然而，这是非常静态的。 我试图弄清楚如何使用从数据库获取的数据来做到这一点，在数据库中，树的深度在编译时是未知的。

我认为我可能需要一些递归方法来实现它，但我不能完全理解实现的样子。

有什么想法吗？

下面是来自primefaces的示例代码

private TreeNode root; private TreeNode selectedNode; public TreeBean() { root = new DefaultTreeNode("Root", null); TreeNode node0 = new DefaultTreeNode("Node 0", root); TreeNode node1 = new DefaultTreeNode("Node 1", root); TreeNode node2 = new DefaultTreeNode("Node 2", root); TreeNode node00 = new DefaultTreeNode("Node 0.0", node0); TreeNode node01 = new DefaultTreeNode("Node 0.1", node0); TreeNode node10 = new DefaultTreeNode("Node 1.0", node1); TreeNode node11 = new DefaultTreeNode("Node 1.1", node1); TreeNode node000 = new DefaultTreeNode("Node 0.0.0", node00); TreeNode node001 = new DefaultTreeNode("Node 0.0.1", node00); TreeNode node010 = new DefaultTreeNode("Node 0.1.0", node01); TreeNode node100 = new DefaultTreeNode("Node 1.0.0", node10); } 

Answer 1

 private TreeNode root; private TreeNode selectedNode; public TreeBean() { root = new DefaultTreeNode("Root", null); List rootNodes = SearchDao.getRootNodes(); Iterator it = rootNodes.iterator(); while (it.hasNext()) { TreeNode node1 = new DefaultTreeNode(**it.next()**, root); **/* in place of it.next() I need to display empName. When I click on empName, I need to get the Id(Pkey). */** } } public TreeNode getRoot() { return root; } public TreeNode getSelectedNode() { return selectedNode; } public void setSelectedNode(TreeNode selectedNode) { this.selectedNode = selectedNode; } public void addChildNode(ActionEvent actionEvent) { System.out.println("Selected Node: "+getSelectedNode().toString()); TreeNode newNode = new DefaultTreeNode("Node New", getSelectedNode()); getSelectedNode().setExpanded(true); } public void addTopicBelow(ActionEvent actionEvent){ TreeNode newNode = new DefaultTreeNode("Node New", getSelectedNode().getParent()); } public void deleteNode(ActionEvent actionEvent){ System.out.println("Node to be deleted: "+getSelectedNode().toString()); //getSelectedNode(). } 

Answer 2

在我看来，Primefaces的示例代码也是非常静态的。 我有同样的问题，我通过为每个父节点创建一个虚拟子节点来解决它。 扩展父节点时，方法’ onNodeExpand ‘删除虚拟子节点并添加真实子节点。

         package com.test.web; import java.io.Serializable; import javax.annotation.PostConstruct; import javax.enterprise.context.SessionScoped; import javax.inject.Named; import org.primefaces.event.NodeExpandEvent; import org.primefaces.model.DefaultTreeNode; import org.primefaces.model.TreeNode; @Named(value = "treeController") @SessionScoped public class TreeController implements Serializable { private TreeNode root; @PostConstruct public void buildTree() { root = new DefaultTreeNode("Root", null); createNode("Node 0", root); createNode("Node 1", root); createNode("Node 2", root); } public TreeNode getRoot() { return root; } public void setRoot(TreeNode root) { this.root = root; } public void onNodeExpand(NodeExpandEvent event) { DefaultTreeNode parent = (DefaultTreeNode) event.getTreeNode(); if (parent.getChildCount() == 1 && parent.getChildren().get(0).getData().toString().equals("DUMMY")) { parent.getChildren().remove(0); createNode("Node A", parent); createNode("Node B", parent); createNode("Node C", parent); } } private void createNode(String tag, TreeNode parent) { TreeNode node = new DefaultTreeNode(tag, parent); // Create Dummy node, just to make the parent node expandable new DefaultTreeNode("DUMMY", node); } }