为什么不下载文件？

嗨我做了这个小程序来凑一些HTML信息，但它没有下载一些文件...为什么不下载文件？

下面的代码：

using HtmlAgilityPack; 
using System; 
using System.Collections.Generic; 
using System.Linq; 
using System.Net; 
using System.Text; 
using System.Threading.Tasks; 

namespace ConsoleApplication2 
{ 
    class Program 
    { 


     static void Main(string[] args) 
     { 
      using (System.Net.WebClient client = new WebClient()) 
      { 

       List<string> source = new List<string>(); 

       HtmlWeb web = new HtmlWeb(); 
       string url = "http://www.jornaldenegocios.pt/mercados/bolsa/detalhe/wall_street_cada_vez_mais_perto_de_maximo_historico.html"; 
       HtmlDocument document = web.Load(url); 

       var head = document.DocumentNode.SelectSingleNode("//head"); 
       var meta = head.SelectNodes("//meta").AsEnumerable(); 
       var link = document.DocumentNode.SelectSingleNode("//head").SelectNodes("//link").AsEnumerable(); 
       var urls = document.DocumentNode.Descendants("img") 
         .Select(e => e.GetAttributeValue("src", null)) 
         .Where(s => !String.IsNullOrEmpty(s)); 

       var titulo = ""; 
       var descricao = ""; 
       var linkImg = ""; 
       var linkIcon = ""; 
       var linkImgAlt = ""; 
       int length = 0; 

       Uri myUri = new Uri(url); 
       string host = myUri.Host; 


       var fbProperties = (head.SelectNodes("//meta[contains(@property, 'og:')]") ?? Enumerable.Empty<HtmlNode>()) 
        .ToDictionary(n => n.Attributes["property"].Value, n => n.Attributes["content"].Value); 


       linkIcon = (head.SelectSingleNode("//link[contains(@rel, 'apple-touch-icon')]")?.Attributes["href"]?.Value) ?? 
        (head.SelectSingleNode("//link[contains(@rel, 'icon')]")?.Attributes["href"]?.Value) ?? 
        host + "/favicon.ico"; 


       var title = head.SelectSingleNode("//title")?.InnerText; 



       if (fbProperties.TryGetValue("og:title", out titulo) == false || titulo == null) 
       { 
        titulo = (title ?? host); 
       } 

       if (fbProperties.TryGetValue("og:description", out descricao) == false || descricao == null) 
       { 
        descricao = ("none"); 
       } 

       if (fbProperties.TryGetValue("og:image", out linkImg) == false || linkImg == null) 
       { 
        linkImg = (linkImgAlt ?? "none"); 
       } 

       foreach (var node in urls) 
       { 
        source.Add(node); 
       } 

       foreach (var links in source) 
       { 
        length = client.DownloadData(links).Length; 

        if (length<client.DownloadData(links).Length) 
        { 
         linkImgAlt = links; 
        } 

       } 




       Console.WriteLine(""); 
       Console.WriteLine("Titulo:"); 
       Console.WriteLine(titulo); 
       Console.WriteLine(""); 
       Console.WriteLine("Descriçao:"); 
       Console.WriteLine(descricao); 
       Console.WriteLine(""); 
       Console.WriteLine("Link da Imagem:"); 
       Console.WriteLine(linkImg); 
       Console.WriteLine(""); 
       Console.WriteLine("Link do Icon:"); 
       Console.WriteLine(linkIcon); 
       Console.WriteLine(""); 
       Console.WriteLine("Link da Imagem:"); 
       Console.WriteLine(length); 
       Console.WriteLine(""); 
       Console.WriteLine("Link da Imagem:"); 
       Console.WriteLine(linkImgAlt); 

       Console.ReadLine(); 
      } 
     } 
    } 
}

，任何东西都工作得很好只是这个小部分是给我一些问题：

foreach (var node in urls) 
{ 
    source.Add(node); 
} 

foreach (var links in source) 
{    
    length = client.DownloadData(links).Length; 

    if (length<client.DownloadData(links).Length) 
    { 
     linkImgAlt = links; 
    } 
}

以下是错误我得到通过运行程序：

的System.dll中发生类型'System.Net.WebException'的未处理异常

附加信息：找不到文件'C：\ i \ closePestana.png'。

打印：http://i.imgur.com/C9JPjtk.png

我想，这是不是下载的文件，这就是为什么给我这个错误消息。你能帮我解决这个问题吗？

谢谢。

来源

2016-06-09 João Figueiredo

我没有回答......但是如果有人遇到了我遇到的一些问题，这里就是解决方案。

using HtmlAgilityPack; 
using System; 
using System.Collections.Generic; 
using System.Linq; 
using System.Net; 
using System.Net.Http; 
using System.Text; 
using System.Threading.Tasks; 

namespace ConsoleApplication2 
{ 
    class Program 
    { 


     static void Main(string[] args) 
     { 
      using (var client = new HttpClient()) 
      { 

       List<string> source = new List<string>(); 

       HtmlWeb web = new HtmlWeb(); 
       string url = "http://www.jornaldenegocios.pt/mercados/bolsa/detalhe/wall_street_cada_vez_mais_perto_de_maximo_historico.html"; 
       HtmlDocument document = web.Load(url); 
       Uri myUri = new Uri(url); 
       string host = myUri.Host; 

       var head = document.DocumentNode.SelectSingleNode("//head"); 
       var meta = head.SelectNodes("//meta").AsEnumerable(); 
       var link = document.DocumentNode.SelectSingleNode("//head").SelectNodes("//link").AsEnumerable(); 
       var urls = document.DocumentNode.SelectNodes("//img") 
         .Select(e => e.GetAttributeValue("src", null)) 
         .Where(s => !string.IsNullOrEmpty(s)) 
         .Where(s => !s.StartsWith("//")) 
         .Select(s => s.StartsWith("http") ? s : myUri.Scheme + "://" + host + s); 

       var titulo = ""; 
       var descricao = ""; 
       var linkImg = ""; 
       var linkIcon = ""; 
       var linkImgAlt = ""; 
       var length = 0L; 



       var fbProperties = (head.SelectNodes("//meta[contains(@property, 'og:')]") ?? Enumerable.Empty<HtmlNode>()) 
        .ToDictionary(n => n.Attributes["property"].Value, n => n.Attributes["content"].Value); 


       linkIcon = (head.SelectSingleNode("//link[contains(@rel, 'apple-touch-icon')]")?.Attributes["href"]?.Value) ?? 
        (head.SelectSingleNode("//link[contains(@rel, 'icon')]")?.Attributes["href"]?.Value) ?? 
        host + "/favicon.ico"; 


       var title = head.SelectSingleNode("//title")?.InnerText; 



       if (fbProperties.TryGetValue("og:title", out titulo) == false || titulo == null) 
       { 
        titulo = (title ?? host); 
       } 

       if (fbProperties.TryGetValue("og:description", out descricao) == false || descricao == null) 
       { 
        descricao = ("none"); 
       } 

       if (fbProperties.TryGetValue("og:image", out linkImg) == false || linkImg == null) 
       { 
        linkImg = (linkImgAlt ?? "none"); 
       } 

       foreach (var node in urls) 
       { 
        source.Add(node); 
       } 



       foreach (var links in source) 
       { 
        try 
        { 
         var response = client.SendAsync(new HttpRequestMessage 
         { 
          Method = HttpMethod.Head, 
          RequestUri = new Uri(links) 
         }).Result; 

         var fileLength = response.Content.Headers.ContentLength; 

         Console.WriteLine($"{links}: {fileLength} bytes"); 

         if (length < fileLength) 
         { 
          linkImgAlt = links; 
          length = fileLength ?? 0; 
         } 

        } 
        catch (Exception e) 
        { 
         Console.WriteLine(e); 
        } 

       } 


       Console.WriteLine(""); 
       Console.WriteLine("Titulo:"); 
       Console.WriteLine(titulo); 
       Console.WriteLine(""); 
       Console.WriteLine("Descriçao:"); 
       Console.WriteLine(descricao); 
       Console.WriteLine(""); 
       Console.WriteLine("Link da Imagem:"); 
       Console.WriteLine(linkImg); 
       Console.WriteLine(""); 
       Console.WriteLine("Link do Icon:"); 
       Console.WriteLine(linkIcon); 
       Console.WriteLine(""); 
       Console.WriteLine("Link da Imagem:"); 
       Console.WriteLine(length); 
       Console.WriteLine(""); 
       Console.WriteLine("Link da Imagem (alt):"); 
       Console.WriteLine(linkImgAlt); 

       Console.ReadLine(); 
      } 
     } 
    } 
}

来源

2016-06-09 14:22:05

为什么不下载文件？

回答

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