Question

大家好，我是VSTO加载项的新手，我正在开发一个项目，应该能够从用户指定的位置获取任何excel文件并进行修改。它可以正常工作，直到用户从sharepoint中选择一个文件（这通过文件打开器工作，以便用户可以浏览到任何位置）。我查看了Microsoft文档和在线，甚至找不到如何执行此操作的入门指南。关于如何从sharepoint获取文件并修改它的任何建议？

Answer 1

通常，Excel对象模型可以处理本地文件。因此，我建议在进行任何修改之前在本地硬盘上下载文件。

例如，您可以使用以下代码从URL下载文件：

using System;
using System.ComponentModel;
using System.IO;
using System.Net;
using System.Threading;

class FileDownloader
{
    private readonly string _url;
    private readonly string _fullPathWhereToSave;
    private bool _result = false;
    private readonly SemaphoreSlim _semaphore = new SemaphoreSlim(0);

    public FileDownloader(string url, string fullPathWhereToSave)
    {
        if (string.IsNullOrEmpty(url)) throw new ArgumentNullException("url");
        if (string.IsNullOrEmpty(fullPathWhereToSave)) throw new  ArgumentNullException("fullPathWhereToSave");

        this._url = url;
        this._fullPathWhereToSave = fullPathWhereToSave;
    }

    public bool StartDownload(int timeout)
    {
        try
        {
            System.IO.Directory.CreateDirectory(Path.GetDirectoryName(_fullPathWhereToSave));

            if (File.Exists(_fullPathWhereToSave))
            {
                File.Delete(_fullPathWhereToSave);
            }
            using (WebClient client = new WebClient())
            {
                var ur = new Uri(_url);
                // client.Credentials = new NetworkCredential("username", "password");
                client.DownloadProgressChanged += WebClientDownloadProgressChanged;
                client.DownloadFileCompleted += WebClientDownloadCompleted;
                Console.WriteLine(@"Downloading file:");
                client.DownloadFileAsync(ur, _fullPathWhereToSave);
                _semaphore.Wait(timeout);
                return _result && File.Exists(_fullPathWhereToSave);
            }
       }
       catch (Exception e)
       {
            Console.WriteLine("Was not able to download file!");
            Console.Write(e);
            return false;
        }
       finally
       {
            this._semaphore.Dispose();
       }
    }

    private void WebClientDownloadProgressChanged(object sender, DownloadProgressChangedEventArgs e)
    {
        Console.Write("\r     -->    {0}%.", e.ProgressPercentage);
    }

    private void WebClientDownloadCompleted(object sender, AsyncCompletedEventArgs args)
    {
        _result = !args.Cancelled;
        if (!_result)
        {
            Console.Write(args.Error.ToString());
        }
        Console.WriteLine(Environment.NewLine + "Download finished!");
        _semaphore.Release();
    }

    public static bool DownloadFile(string url, string fullPathWhereToSave, int timeoutInMilliSec)
    {
        return new FileDownloader(url, fullPathWhereToSave).StartDownload(timeoutInMilliSec);
    }
}

使用代码：

static void Main(string[] args)
{
    var success = FileDownloader.DownloadFile(fileUrl, fullPathWhereToSave, timeoutInMilliSec);
    Console.WriteLine("Done  - success: " + success);
    Console.ReadLine();
}

从Excel VSTO加载项

1 个答案: