Question

我目前正在开发一个使用Asp.Net和C＃开发的网站。我正在使用Asp.Net Handler来允许用户下载文件。我可以下载文件没问题。但是我需要记录哪些文件已成功下载。这部分似乎对我不起作用。例如。如果我点击要下载的文件然后在浏览器提示上单击取消，我的代码仍会写入日志。我似乎无法弄清楚如何在文件成功下载后写入仅。

我的代码如下。

public void ProcessRequest(HttpContext context)
{
    string logFilePath = "PathToMyLogFile";
    string filePath = Uri.UnescapeDataString(context.Request.QueryString["file"]);
    string fileName = Path.GetFileName(filePath);

    if (context.Response.IsClientConnected) //Shouldn't this tell me if the client is connected or not?
    {
        using (var writer = new StreamWriter(logFilePath, true))
        {
            if (!File.Exists(logFilePath))
            {
                //Create log file if one does not exist
                File.Create(logFilePath);
            }
            else
            {
                writer.WriteLine("The following file was downloaded \"{0}\" on {1}", fileName, DateTime.Now.ToString("dd/MM/yyyy") + " at " + DateTime.Now.ToString("HH:mm:ss"));
                writer.WriteLine(Environment.NewLine + "-----------------------------------------------------------------------------" + Environment.NewLine);
            }
        }
    }

    context.Response.ContentType = "application/octet-stream";
    context.Response.AppendHeader("Content-Disposition", "attachment;filename=\"" + Path.GetFileName(filePath));
    context.Response.WriteFile(filePath);
    context.Response.End();
}

感谢您的所有帮助和支持。

Answer 1

我尝试创建一个简单的处理程序，它可以检测从服务器端角度取消/中断下载。

在发送数据期间/之后，重要的部分是“context.Response.IsClientConnected”。

此示例将使用随机数据发送无休止的文件。您可以在所有浏览器中测试它，它们将如何表现。我只在Chrome中测试过它。

/// <summary>
/// Writes random data.
/// </summary>
public class NeverendingFile : IHttpHandler {
    public bool IsReusable {
        get { return false; }
    }

    public void ProcessRequest(HttpContext context) {
        context.Response.Buffer = false;
        context.Response.BufferOutput = false;
        context.Response.ContentType = "application/octet-stream";
        context.Response.AppendHeader("Content-Disposition", "attachment;filename=\"Neverendingfile.dat\"");
        context.Response.Flush();

        // flag used for debuging, in production it will be always false => writing into output stream will nevere ends
        var shouldStop = false;
        for(var i = 0; !shouldStop; i++) {
            // chunk contains random data
            var chunk = Guid.NewGuid().ToByteArray();

            for (var a = 0; a < 1000; a++) {
                context.Response.OutputStream.Write(chunk, 0, chunk.Length);
            }
            context.Response.OutputStream.Flush();
            // sleep is just for slowing the download
            System.Threading.Thread.Sleep(10);

            if (!context.Response.IsClientConnected) {
                // the download was canceled or broken
                return;
            }
        }
    }
}

修改编辑过的源代码：

public void ProcessRequest(HttpContext context) { string logFilePath = "PathToLogFile"; //Determine the file path string filePath = Uri.UnescapeDataString(context.Request.QueryString["file"]); //Determine the file name string fileName = Path.GetFileName(filePath); context.Response.Buffer = false; context.Response.BufferOutput = false; context.Response.ContentType = "application/octet-stream"; context.Response.AppendHeader("Content-Disposition", "attachment;filename=\"" + Path.GetFileName(filePath)); context.Response.WriteFile(filePath); context.Response.Flush(); context.Response.OutputStream.Flush(); if (!context.Response.IsClientConnected) { // the download was canceled or broken using (var writer = new StreamWriter(logFilePath, true)) { if (!File.Exists(logFilePath)) { //Create log file if one does not exist File.Create(logFilePath); } else { writer.WriteLine("The Download was canceled"); } } return; } context.Response.End(); }

Answer 2

我假设下载和取消按钮都在同一页面上。我创建了以下示例来检查文件是否已经开始下载，同时取消使用具有标记的单例类＆＃34; isFileDownload＆＃34;这样就不会为同一用户的每个请求初始化标志值。

每次请求来自用户时，请指定＆＃34; isFileDownload＆＃34; JSON 变量到＆＃34; isFileDownload＆＃34;单身阶级。
当文件下载请求进入处理程序时，＆＃34; isFileDownload＆＃34;单身人士将被设为真。在将响应发送回用户的同时，检查＆＃34; isFileDownload＆＃34;真正的登录否则不要。
如果用户点击下载按钮，那么＆＃34; isFileDownload＆＃34; = true并且用户在下载文件之前单击取消按钮然后＆＃34; isFileDownload＆＃34; = false。
因为＆＃34; isFileDownload＆＃34; property是singleton类的一部分，同一个实例将被更新。

仅供参考，我是处理人员的新手。如果我在发布此内容时遗漏了一些内容，请提前预订

处理程序类：

public class DownloadFile : IHttpHandler
{

    public void ProcessRequest(HttpContext context)
    {
        string fileName = @"test.txt";
        string filePath = context.Server.MapPath("/test.txt");
        string logFilePath = context.Server.MapPath("/Log.txt");
        //string filePath = Uri.UnescapeDataString(context.Request.QueryString["file"]);
        //string fileName = Path.GetFileName(filePath);
        Singleton s = Singleton.Instance;
        s.isFileDownload = Convert.ToBoolean(context.Request.Form["isFileDownload"]);
        if (context.Response.IsClientConnected) //Shouldn't this tell me if the client is connected or not?
        {

            using (var writer = new StreamWriter(logFilePath,true))
            {
                if (!File.Exists(logFilePath))
                {
                    //Create log file if one does not exist
                    File.Create(logFilePath);
                }
                else
                {
                    writer.WriteLine("The following file was downloaded \"{0}\" on {1}", fileName, DateTime.Now.ToString("dd/MM/yyyy") + " at " + DateTime.Now.ToString("HH:mm:ss"));
                    writer.WriteLine(Environment.NewLine + "-----------------------------------------------------------------------------" + Environment.NewLine);
                }
            }
        }

        //To mock the large file download
        if (s.isFileDownload)
        System.Threading.Thread.Sleep(10000);

        if (context.Response.IsClientConnected )
        {
            if (s.isFileDownload){
            System.Threading.Thread.Sleep(100);
            context.Response.ContentType = "application/octet-stream";
            context.Response.AppendHeader("Content-Disposition", "attachment;filename=\"" + Path.GetFileName(filePath));
            context.Response.WriteFile(filePath);
            context.Response.OutputStream.Flush();
            context.Response.End();
        }
            else
            {
                return;
            }
        }
        else
        {
            return;
        }


    }

    public bool IsReusable
    {
        get
        {
            return false;
        }
    }
}

单身人士课程： Reference

public sealed class Singleton
{
    private static volatile Singleton instance;
    private static object syncRoot = new Object();

    private Singleton() { }

    public static Singleton Instance
    {
        get
        {
            if (instance == null)
            {
                lock (syncRoot)
                {
                    if (instance == null)
                        instance = new Singleton();
                }
            }

            return instance;
        }
    }

    public bool isFileDownload { get; set; }
}

Html页面：

＆＃13;

$(document).ready(function(){ 
var isFileDownload = false;
        $("#download").click(function () {
            isFileDownload = true;
            console.log(isFileDownload);
            $.ajax({
                method: "POST",
                url: "DownloadFile.ashx",
                data: { isFileDownload:true }
            }).done(function (data) {
                alert(data);
               
            });
        });

        $("#cancel").click(function () {
            if (isFileDownload) {
                $.ajax({
                    method: "POST",
                    url: "DownloadFile.ashx",
                    data: { isFileDownload: false }
                }).done(function (data) {
                    alert("canceld");
                    isFileDownload = false;
                });
            }
        });
        $(document).ajaxComplete(function () {
            isFileDownload = false;
        });
)};

＆＃13;

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<body>
<button type="button" value="DownLoad" id="download" title="Download">Download</button>
<button type="button" value="Cancel" id="cancel" title="Cancel">Cancel</button>
  </body>

＆＃13;

Answer 3

当出现浏览器弹出窗口时，表示服务器已开始将数据发送（流）到客户端。实际上无法检测文件下载是否成功。您只能检测发送到客户端的字节数，如果字节数等于文件长度，您可以假设客户端能够下载文件，但您无法获得证明该文件已成功保存在客户端的计算机/环境中。

示例：如果我在linux下载并将流转发到/ dev / null，您将看到我已经下载了该文件，但实际上该文件将不存在于我的机器上。

使用Handler跟踪文件

3 个答案: