下载文件并自动保存到文件夹

Question

我正在尝试制作用于从我的站点下载文件的 UI。该站点有 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，它只是从一个临时文件夹中打开。

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);
}

完整源代码： http://en.paidpaste.com/LqEmiQ

Answer 1

我的程序完全按照你的要求做，没有提示什么的，请看下面的代码。

此代码将创建所有必要的目录（如果它们尚不存在）：

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

这段代码会将给定的文件下载到给定的目录（在之前的sn-p创建之后：

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
    }

因此，使用这两段代码，您可以创建所有目录，然后告诉下载器（这不会提示您将文件下载到该位置。

Answer 2

如果您不想使用“WebClient”或/并且需要使用 System.Windows.Forms.WebBrowser，例如因为你想先模拟登录，你可以使用这个扩展的 WebBrowser，它从 Windows URLMON Lib 中挂钩“URLDownloadToFile”方法并使用 WebBrowser 的上下文

信息：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);
            }
        }
    }

Answer 3

为什么不完全绕过 WebClient 的文件处理部分。也许类似这样：

    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 4

嗯，您的解决方案几乎可以正常工作。为了简单起见，需要考虑以下几点：

• 仅针对您知道会发生下载的特定 URL 取消默认导航，否则用户将无法导航到任何地方。这意味着您不得更改您的网站下载 URL。

• DownloadFileAsync 不知道服务器在 Content-Disposition 标头中报告的名称，因此您必须指定一个，或者在可能的情况下从原始 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 浏览器控件将不再为您执行此操作。

示例代码，将下载到textBox1 中指定的目录，但文件名随机，并且没有任何额外的错误处理：

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");
}

这个解决方案应该可以工作，但很容易被破坏。尝试考虑一些 Web 服务，列出可供下载的可用文件并为其制作自定义 UI。它会更简单，您将控制整个过程。

Answer 5

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

我的建议是尝试同步下载，因为它更直接。 在尝试此操作时，您可能会了解 webclient 参数是否错误或文件格式不正确。

这是一个代码示例..

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 6

更简单的解决方案是使用 Chrome 下载文件。通过这种方式，您不必手动单击保存按钮。

using System;
using System.Diagnostics;
using System.ComponentModel;

namespace MyProcessSample
{
    class MyProcess
    {
        public static void Main()
        {
            Process myProcess = new Process();
            myProcess.Start("chrome.exe","http://www.com/newfile.zip");
        }
    }
}