The TreeView control displays a hierarchy of nodes as a tree.
For example: the top-level directory is the root (C:), each subdirectory under the C disk is a child node, and each subdirectory has its own child node TreeView
properties and methods:
| Attributes | illustrate |
|---|---|
| CheckBoxes | Indicates whether a checkbox appears next to the node |
| ImageList | Specifies an ImageList object containing node icons. ImageList object is a collection containing Image objects |
| Nodes | Returns the TreeNode collection in the control as a TreeNodeCollection |
| SelectedNode | selected node |
Common events:
AfterSelect: Generated when the selected node changes
TreeNode properties and methods:
| TreeNode property | illustrate |
|---|---|
| Checked | Indicates whether the TreeNode is selected |
| FirstNode | The first node of the specified Nodes collection |
| FullPath | The path of nodes starting from several roots |
| ImageIndex | When selecting a node, specify the index of the image to be displayed in the ImageList of the TreeView |
| LastNode | Specifies the last node in the Nodes collection |
| NextNode | next sibling node |
| Nodes | A collection of TreeNodes contained in the current node |
| PrevNode | previous sibling node |
| SelectedImageIndex | Specifies the index of the image to display in the TreeView's ImageList when a node is selected |
| Text | Specifies the text of the TreeNode |
| TreeNode method | illustrate |
|---|---|
| Collapse | Collapse nodes on load |
| Expand | expand node |
| ExpandAll | Expand all child nodes of a node |
| GetNodeCount | Return the number of child nodes |
Example :
Enter a local file directory, and use TreeView to display all folders in the directory
1. Add a Label control, and change the Text property to: "File Path:".
2. Add a TextBox control, elongate it appropriately, and change the Name property to inputTextBox
3. Add a Button control, change the Text property to: "OK", and change the Name property to enterButton
4. Add a TreeView control, adjust the size appropriately, after completion As shown below:
5. Double-click the Button control and write the Click event. The overall procedure is as follows:
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.IO;//添加
namespace TreeView 控件
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void enterButton_Click(object sender, EventArgs e)
{
directoryTreeView.Nodes.Clear();// 每次确定时需要刷新内容
string inputText = inputTextBox.Text; // 获得输入框的内容
// 文件路径存在
if (Directory.Exists(inputText))
{
TreeNode rootNode = new TreeNode(inputText); // 创建树节点
directoryTreeView.Nodes.Add(rootNode); // 加入视图
FindDirectory(inputText, rootNode); //通过递归函数进行目录的遍历
}
// 文件路径不存在
else
{
MessageBox.Show("输入目录不存在！！！");
inputTextBox.Clear(); // 当文件目录不存在时清空控件内容
directoryTreeView.Nodes.Clear();
}
}
// 递归函数 遍历当前目录
void FindDirectory(string nowDirectory, TreeNode parentNode)
{
try // 当文件目录不可访问时，需要捕获异常
{
// 获取当前目录下的所有文件夹数组
string[] directoryArray = Directory.GetDirectories(nowDirectory);
if (directoryArray.Length > 0)
{
foreach (string item in directoryArray)
{
// 遍历数组，将节点添加到父亲节点的
string str = Path.GetFileNameWithoutExtension(item);
TreeNode node = new TreeNode(str);
parentNode.Nodes.Add(node);
FindDirectory(item, node);
}
}
}
catch (Exception)
{
parentNode.Nodes.Add("禁止访问");
}
}
}
}
6. Run the program, enter any existing folder path, and click OK:
