如何使用ASP.NET下载多个文件? [英] How to Download Multiple Files using ASP.NET?

问题描述

我正在尝试使用asp.net下载多个文件.我有一个名为DownloadFileButton的按钮和一个名为FilePath的ArrayList(它包含所有文件路径). 因此，当我单击下载"按钮时，仅下载了一个文件(文件路径"列表中的第一个文件).因为Response.End()导致脚本停止处理.当我注释掉Response.End()时，我在Response.ClearHeaders()处得到了异常.

I am trying to Download multiple files using asp.net. I have a Button called DownloadFileButton and a ArrayList called FilePath(It holds all the File paths). So when i click the Download Button only 1 file is downloaded(the first file in the FilePath List). Because Response.End() causes the script to stop processing. when i comment out the Response.End() then i get an exception at Response.ClearHeaders().

如何克服这个问题?

我的代码:

protected void DownloadFileButton_Click(object sender, EventArgs e)
{
for (int i = 0; i < FilePath.Count; i++)
    {
    string path = FilePath[i];

            FileInfo file = new FileInfo(path);

            if(file.Exists)
            {
                Response.Clear();
                Response.ClearHeaders();
                Response.ClearContent();
                Response.AddHeader("Content-Disposition", "attachment; filename=" + file.Name);
                Response.AddHeader("Content-Length", file.Length.ToString());
                Response.Flush();
                Response.TransmitFile(file.FullName);
                Response.End();
            }
        }
    }
}

推荐答案

如何克服这个问题?

how to overcome this?

一个词(或两个词)，您不会.

In a word (or two), you don't.

HTTP是一个请求/响应系统.任何答复都必须作为对请求的答复.鉴于此，您无法发送单个请求的多个响应.如果没有其他要求，那么就不会有客户端在监听那些响应(因为它已经获得了正在等待的响应).

HTTP is a request/response system. Any response has to come as a reply to a request. Given that, you can't send multiple responses to a single request. If nothing else, there would be no client listening for those responses (because it already got the response it was waiting for).

因此，从本质上讲，您有两个选择:

So essentially you have two options:

1. 发出多个请求，每个下载的文件"一个.这将为客户带来多个期望.
2. 使用服务器端代码中的某些存档工具(Zip库是非常标准的)将文件合并为单个文件，然后发送那个作为响应.然后，客户端将需要取消存档. (如果客户端是用户，则可以手动执行.自解压可执行文件Zip可以帮助您解决问题.如果客户端是应用程序，则可以在客户端使用同一库提取存档内容并保存.文件.)

1. Issue multiple requests, one for each "file" being downloaded. This will create multiple responses for the client to expect.
2. Combine the files into a single file using some archiving tool (Zip libraries are pretty standard for this) in the server-side code and send that file as the response. The client would then need to un-archive it. (If the client is a user, they'd do it manually. A self-extracting executable Zip helps with that. If the client is an application, the same library can be used client-side to extract the contents of the archive and save the files.)

一个请求=一个响应.

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