Question

我的Listbox已经包含这样的链接：http://example.com/sorted/Avicii/Avicii+-+Wake+Me+Up.mp3我想在同一时间下载所有建议吗？这段代码我用来下载单个文件

 private void txtUrl_TextChanged(object sender, EventArgs e)
    {
        try
        {
            //  function that enter the file name automatically in the savefiledialog.
            Uri uri = new Uri(txtUrl.Text);
            // Save the file name to the string.
            filename = Path.GetFileName(uri.LocalPath);
        }
        catch
        {
            // no need  need an exception message.
        }
    }
    private void DownloadFile(string url, string save)
    {
        using (var client = new WebClient())
        {
            // Run code every time the download changes.
            client.DownloadProgressChanged += new DownloadProgressChangedEventHandler(Changed);
            // Run codes when file download has been completed.
            client.DownloadFileCompleted += new AsyncCompletedEventHandler(Completed);
                           client.DownloadFileAsync(new Uri(url), save);

Answer 1

解决方案可能如下所示：

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Net;

namespace SillyCSharpNameSpace
{
    public class VerboseDownloaderClassName
    {
        private string downloadFile(string url, string localDir)
        {
            try
            {
                var localPath = Path.Combine(localDir, Path.GetFileName(url));
                using (var wc = new WebClient())
                {
                    wc.DownloadFile(url, localPath);
                    return localPath;
                }
            }
            catch (Exception e)
            {
                Console.WriteLine(e);
                return null;
            }
        }

        public void DownloadAll(List<string> urls)
        {
            urls.AsParallel()
                .Where(url => !string.IsNullOrWhiteSpace(url))
                .WithDegreeOfParallelism(20)
                .Select(url => downloadFile(url, "."));
        }
    }
}

我确定如果你使用WinForms或ASP.NET，你可以弄清楚如何从列表框项中获取url字符串。请注意，Path.GetFileName（）仅适用于您提供的表单 - URL末尾的文件名，没有任何URL参数。 AsParallel方法将下载工作并行化为20＆＃34;线程＆＃34;。我认为它应该足以达到你的目的。

奖金。这与F＃相同，只是因为我可以; o）

open System.IO
open System.Net
open FSharp.Collections.ParallelSeq // from NuGet FSharp.Collections.ParallelSeq

let downloadFile dir url =
    let localPath = Path.Combine(dir, Path.GetFileName url)
    try
        use wc = new WebClient()
        wc.DownloadFile(url, localPath)
        Some localPath
    with ex ->
        printfn "Can't download file from %s: %A" url ex
        None

let downloadAll (urls: string list) =
    urls
    |> PSeq.withDegreeOfParallelism 20 // 20 threads
    |> PSeq.choose (downloadFile ".")

同时下载多个文件

1 个答案: