下载文件并将其自动保存到文件夹

Question

我正在尝试制作用于从我的网站下载文件的用户界面。该网站有zip文件，这些文件需要下载到用户输入的目录中。但是，我无法成功下载该文件，只是从临时文件夹中打开。

代码：

private void webBrowser1_Navigating(object sender, WebBrowserNavigatingEventArgs e) 
{ 
     e.Cancel = true; 
     string filepath = null; 
      filepath = textBox1.Text; 
      WebClient client = new WebClient(); 
      client.DownloadFileCompleted += new AsyncCompletedEventHandler(client_DownloadFileCompleted); 
      client.DownloadFileAsync(e.Url, filepath); 
} 

全部源代码： http://en.paidpaste.com/LqEmiQ

Answer 1

为什么不完全绕过WebClient的文件处理部分。也许类似这样的东西：

private void webBrowser1_Navigating(object sender, WebBrowserNavigatingEventArgs e) 
    { 
     e.Cancel = true; 
     WebClient client = new WebClient(); 

     client.DownloadDataCompleted += new DownloadDataCompletedEventHandler(client_DownloadDataCompleted); 

     client.DownloadDataAsync(e.Url); 
    } 

    void client_DownloadDataCompleted(object sender, DownloadDataCompletedEventArgs e) 
    { 
     string filepath = textBox1.Text; 
     File.WriteAllBytes(filepath, e.Result); 
     MessageBox.Show("File downloaded"); 
    } 

Answer 2

在http://www.csharp-examples.net/download-files/ 和MSDN文档上的WebClient看看 http://msdn.microsoft.com/en-us/library/system.net.webclient.aspx

我的建议是尝试同步下载作为其更直接。 您可能会在尝试此操作时得到有关Web客户端参数是否有误或文件格式不正确的提示。

下面是一个代码示例..

private void btnDownload_Click(object sender, EventArgs e) 
{ 
    string filepath = textBox1.Text; 
    WebClient webClient = new WebClient(); 
    webClient.DownloadFileCompleted += new AsyncCompletedEventHandler(Completed); 
    webClient.DownloadProgressChanged += new DownloadProgressChangedEventHandler(ProgressChanged); 
    webClient.DownloadFileAsync(new Uri("http://mysite.com/myfile.txt"), filepath); 
} 

private void ProgressChanged(object sender, DownloadProgressChangedEventArgs e) 
{ 
    progressBar.Value = e.ProgressPercentage; 
} 

private void Completed(object sender, AsyncCompletedEventArgs e) 
{ 
    MessageBox.Show("Download completed!"); 
} 

Answer 3

那么，你的解决方案几乎工作。有几件事情要考虑，以保持它的简单：

• 取消默认导航只为你知道会发生下载特定的网址，或者用户将不能够在任何地方浏览。这意味着你不能改变你的网站下载网址。

• DownloadFileAsync不知道服务器在Content-Disposition标题中报告的名称，因此您必须指定一个，或者如果可能的话从原始URL计算一个。您不能只指定文件夹，并期望自动检索文件名。

• 您必须处理来自DownloadCompleted回调的下载服务器错误，因为Web浏览器控件不再适合您。

样品一段代码，将下载到的textBox1指定的目录中，但有一个随机文件名，并且没有任何附加的错误处理：

private void webBrowser1_Navigating(object sender, WebBrowserNavigatingEventArgs e) { 
    /* change this to match your URL. For example, if the URL always is something like "getfile.php?file=xxx", try e.Url.ToString().Contains("getfile.php?") */ 
    if (e.Url.ToString().EndsWith(".zip")) { 
     e.Cancel = true; 
     string filePath = Path.Combine(textBox1.Text, Path.GetRandomFileName()); 
     var client = new WebClient(); 
     client.DownloadFileCompleted += client_DownloadFileCompleted; 
     client.DownloadFileAsync(e.Url, filePath); 
    } 
} 

private void client_DownloadFileCompleted(object sender, AsyncCompletedEventArgs e) { 
    MessageBox.Show("File downloaded"); 
} 

这个解决方案应该工作，但可以很容易破碎。尝试考虑一些列出可供下载的文件的Web服务，并为其创建自定义UI。它会更简单，你将控制整个过程。

Answer 4

我的程序完全符合你的要求，没有任何提示或任何内容，请参阅下面的代码。

此代码将创建所有必需的目录，如果他们不这样做已经存在：

Directory.CreateDirectory(C:\dir\dira\dirb); // This code will create all of these directories 

此代码将指定的文件下载到指定目录（已经由先前的片断创建后：

private void install() 
    { 
     WebClient webClient = new WebClient();               // Creates a webclient 
     webClient.DownloadFileCompleted += new AsyncCompletedEventHandler(Completed);     // Uses the Event Handler to check whether the download is complete 
     webClient.DownloadProgressChanged += new DownloadProgressChangedEventHandler(ProgressChanged); // Uses the Event Handler to check for progress made 
     webClient.DownloadFileAsync(new Uri("http://www.com/newfile.zip"), @"C\newfile.zip");   // Defines the URL and destination directory for the downloaded file 
    } 

所以使用这两段代码，你可以创建所有的目录，然后告诉下载（不提示您将文件下载到该位置。

Answer 5

如果不希望使用“Web客户端”或/和需要使用System.Windows.Forms.WebBrowser例如因为你想先模拟登录，就可以使用这个扩展的web浏览器鱼钩从Windows URLMON库的“URLDownloadToFile”方法，并使用web浏览器

相关信息的语境：http://www.pinvoke.net/default.aspx/urlmon/URLDownloadToFile%20.html

using System; 
using System.IO; 
using System.Runtime.InteropServices; 
using System.Windows.Forms; 

namespace dataCoreLib.Net.Webpage 
{ 
     public class WebBrowserWithDownloadAbility : WebBrowser 
     { 
      /// <summary> 
      /// The URLMON library contains this function, URLDownloadToFile, which is a way 
      /// to download files without user prompts. The ExecWB(_SAVEAS) function always 
      /// prompts the user, even if _DONTPROMPTUSER parameter is specified, for "internet 
      /// security reasons". This function gets around those reasons. 
      /// </summary> 
      /// <param name="callerPointer">Pointer to caller object (AX).</param> 
      /// <param name="url">String of the URL.</param> 
      /// <param name="filePathWithName">String of the destination filename/path.</param> 
      /// <param name="reserved">[reserved].</param> 
      /// <param name="callBack">A callback function to monitor progress or abort.</param> 
      /// <returns>0 for okay.</returns> 
      /// source: http://www.pinvoke.net/default.aspx/urlmon/URLDownloadToFile%20.html 
      [DllImport("urlmon.dll", CharSet = CharSet.Auto, SetLastError = true)] 
      static extern Int32 URLDownloadToFile(
       [MarshalAs(UnmanagedType.IUnknown)] object callerPointer, 
       [MarshalAs(UnmanagedType.LPWStr)] string url, 
       [MarshalAs(UnmanagedType.LPWStr)] string filePathWithName, 
       Int32 reserved, 
       IntPtr callBack); 


      /// <summary> 
      /// Download a file from the webpage and save it to the destination without promting the user 
      /// </summary> 
      /// <param name="url">the url with the file</param> 
      /// <param name="destinationFullPathWithName">the absolut full path with the filename as destination</param> 
      /// <returns></returns> 
      public FileInfo DownloadFile(string url, string destinationFullPathWithName) 
      { 
       URLDownloadToFile(null, url, destinationFullPathWithName, 0, IntPtr.Zero); 
       return new FileInfo(destinationFullPathWithName); 
      } 
     } 
    }