如果文件存在 [英] If File Exists

问题描述

此刻，我正在根据下拉列表选择以下内容来更改pdf查看器的文件路径

At the moment I''m using the following to change the file path of a pdf viewer depending on a dropdownlist selection

using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;

public partial class Default : System.Web.UI.Page
{

    protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
    {
        // Make sure you get a valid file path to a pdf in DropDownList1.SelectedValue
        ShowPdf1.FilePath = "attachments/" + DropDownList1.SelectedValue + ".pdf#toolbar=0&navpanes=0&zoom=50";

    }
   
}

我想知道是否可以执行以下操作:

I was wondering if it would be possible to do something like the following:

using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;

public partial class Default : System.Web.UI.Page
{

    protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
    {
If "attachments/" + DropDownList1.SelectedValue + ".pdf" exists
then
        ShowPdf1.FilePath = "attachments/" + DropDownList1.SelectedValue + ".pdf#toolbar=0&navpanes=0&zoom=50";

else
ShowPdf1.FilePath = "attachments/NoFile.pdf#toolbar=0&navpanes=0&zoom=50";

    }
   
}

推荐答案

我认为您的意思是MapPath.这就是您从虚拟地址转到文件地址的方式.

http://msdn.microsoft.com/en-us/library/ms178116.aspx [ ^ ]

祝你好运！

I think you mean MapPath. That''s how you can go from virtual address to file address.

http://msdn.microsoft.com/en-us/library/ms178116.aspx[^]

Good luck!

谢谢，它使我走上了通往解决方案的正确之路.

Thankyou it put me on the right path to a Solution.

using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.IO;

public partial class Default : System.Web.UI.Page
{

    protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
    {
        string filePath = Request.PhysicalApplicationPath + "attachments/" + DropDownList1.SelectedValue + ".pdf";

        FileInfo imageFile = new FileInfo(filePath);
        bool fileExists = imageFile.Exists;

        if (fileExists == false)
            ShowPdf1.FilePath = "attachments/Nofile.pdf#toolbar=0&navpanes=0&zoom=100";
        else
            ShowPdf1.FilePath = "attachments/" + DropDownList1.SelectedValue + ".pdf#toolbar=0&navpanes=0&zoom=50";
    }
}

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