c# - WebClient 下载许多文件错误 — Invalid URI: The URI is empty

Question

我想从 last.fm 下载所有专辑艺术家，每个封面都命名为专辑标题。但是当启动程序时，我得到一个错误：“无效的 URI：URI 是空的。”

程序代码：

public static void GetXML()
        {
            string url = @"http://ws.audioscrobbler.com/2.0/?method=artist.gettopalbums&artist=radiohead&api_key=b25b959554ed76058ac220b7b2e0a026";
            string albumName = String.Empty;
            string coverLink = String.Empty;
            int[] numArr = new int[30];

            for (int x = 1; x < numArr.Length; x++)
            {
                numArr[x] = x;   
            }

           XDocument xml = XDocument.Load(url);

           foreach (var c in numArr)
           {
               var name = xml.XPathSelectElements(String.Format("//album[@rank='{0}']", c))
                             .Select(x => x.Element("name").Value)
                             .ToList();
               foreach (var item in name)
               {
                   albumName = item.ToString();
               }

               var covers = xml.XPathSelectElements(String.Format("//album[@rank='{0}']/image[@size='extralarge']", c))
                          .Select(x => x.Value)
                          .ToList();
               foreach (var item in covers)
               {
                   coverLink = item.ToString();
               }

               WebClient web = new WebClient();
               web.DownloadFileCompleted += new System.ComponentModel.AsyncCompletedEventHandler(web_DownloadFileCompleted);
               web.DownloadFileAsync(new Uri(coverLink), @"X:\Code\T\" + albumName + ".jpg");
           }

        }

Answer 1

您将数组初始化为

for (int x = 1; x < numArr.Length; x++)
{
      numArr[x] = x;   
}

但永远不要设置使用的值numArr[0]（foreach (var c in numArr)并且没有排名= 0的专辑）。

这不是更容易吗？

 var albums = xml.Descendants("album")
        .Select(a => new
        {
            Rank = (int)a.Attribute("rank"),
            Name = a.Element("name").Value,
            ImageUrl = a.XPathSelectElement("image[@size='extralarge']").Value
        })
        .ToList();