Install-Package CefSharp.WinForms

using System;
using System.IO;
using System.Windows.Forms;
using CefSharp;
using CefSharp.WinForms;

public class MainForm : Form
{
    private ChromiumWebBrowser browser;

    public MainForm()
    {
        InitializeComponent();
        InitializeBrowser();
    }

    private void InitializeBrowser()
    {
        // 初始化 CEFSharp
        Cef.Initialize(new CefSettings());

        // 創建 ChromiumWebBrowser 控制項
        browser = new ChromiumWebBrowser("https://example.com");
        this.Controls.Add(browser);
        browser.Dock = DockStyle.Fill;

        // 設置下載處理器
        browser.DownloadHandler = new DownloadHandler();
    }

    public class DownloadHandler : IDownloadHandler
    {
        public void OnBeforeDownload(IWebBrowser browserControl, IBrowser browser, IFrame frame, string url, string suggestedName, string mimeType, bool isNewDownload, IBeforeDownloadCallback callback)
        {
            // 指定下載的保存路徑
            string downloadPath = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments), suggestedName);

            // 開始下載
            callback.Continue(downloadPath, showDialog: false);
        }

        public void OnDownloadUpdated(IWebBrowser browserControl, IBrowser browser, IFrame frame, string url, IDownloadItem downloadItem, IDownloadCallback callback)
        {
            // 可以在這裡處理下載狀態更新
            if (downloadItem.IsComplete)
            {
                MessageBox.Show("下載完成: " + downloadItem.FullPath);
            }
        }
    }
}

using CefSharp;
using System;
using System.IO;

public class DownloadHandler : IDownloadHandler
{
    private readonly string _downloadFolder;

    public DownloadHandler(string downloadFolder)
    {
        // 設定儲存的資料夾
        _downloadFolder = downloadFolder;
    }

    public void OnBeforeDownload(IWebBrowser chromiumWebBrowser, IBrowser browser, DownloadItem downloadItem, IBeforeDownloadCallback callback)
    {
        // 確保資料夾存在
        if (!Directory.Exists(_downloadFolder))
        {
            Directory.CreateDirectory(_downloadFolder);
        }

        // 指定下載的保存路徑
        string downloadPath = Path.Combine(_downloadFolder, downloadItem.SuggestedFileName);

        // 開始下載
        callback.Continue(downloadPath, showDialog: false);
    }

    public void OnDownloadUpdated(IWebBrowser chromiumWebBrowser, IBrowser browser, DownloadItem downloadItem, IDownloadItemCallback callback)
    {
        // 在這裡處理下載狀態更新
        if (downloadItem.IsComplete)
        {
            // 獲取下載的完整路徑和文件名
            string filePath = downloadItem.FullPath;
            string fileName = Path.GetFileName(filePath);

            // 這裡可以使用其他方式通知用戶，例如使用日誌或其他 UI 元素
            Console.WriteLine($"下載完成: {filePath}");
            Console.WriteLine($"文件名: {fileName}");
        }
    }
}