限制要上传的文件类型
我已经删除了我之前关于使用传统asp进行文件上传的问题。 现在我已经切换到.net来实现目标，但我仍然无法限制文件类型，即PDF和DOCX被上传。
后面的代码如下所示：
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.IO;
public partial class CS : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
string[] filePaths = Directory.GetFiles(Server.MapPath("~/Upload/"));
List<ListItem> files = new List<ListItem>();
foreach (string filePath in filePaths)
{
files.Add(new ListItem(Path.GetFileName(filePath), filePath));
}
GridView1.DataSource = files;
GridView1.DataBind();
}
}
protected void UploadFile(object sender, EventArgs e)
{
string fileName = Path.GetFileName(FileUpload1.PostedFile.FileName);
FileUpload1.PostedFile.SaveAs(Server.MapPath("~/Upload/") + fileName);
Response.Redirect(Request.Url.AbsoluteUri);
}
protected void DownloadFile(object sender, EventArgs e)
{
string filePath = (sender as LinkButton).CommandArgument;
Response.ContentType = ContentType;
Response.AppendHeader("Content-Disposition", "attachment; filename=" + Path.GetFileName(filePath));
Response.WriteFile(filePath);
Response.End();
}
protected void DeleteFile(object sender, EventArgs e)
{
string filePath = (sender as LinkButton).CommandArgument;
File.Delete(filePath);
Response.Redirect(Request.Url.AbsoluteUri);
}
}
html页面如下所示：
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="safetyupload.aspx.cs" Inherits="CS" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title></title>
</head>
<body>
<form id="form1" runat="server">
<asp:FileUpload ID="FileUpload1" runat="server" />
<asp:Button ID="btnUpload" runat="server" Text="Upload" OnClick="UploadFile" />
<hr />
<asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="false" EmptyDataText = "No files uploaded">
<Columns>
<asp:BoundField DataField="Text" HeaderText="File Name" />
<asp:TemplateField>
<ItemTemplate>
<asp:LinkButton ID="lnkDownload" Text = "Download" CommandArgument = '<%# Eval("Value") %>' runat="server" OnClick = "DownloadFile"></asp:LinkButton>
</ItemTemplate>
</asp:TemplateField>
<asp:TemplateField>
<ItemTemplate>
<asp:LinkButton ID = "lnkDelete" Text = "Delete" CommandArgument = '<%# Eval("Value") %>' runat = "server" OnClick = "DeleteFile" />
</ItemTemplate>
</asp:TemplateField>
</Columns>
</asp:GridView>
</form>
</body>
</html>
我试过这个，但没有用
protected void UploadFile(object sender, EventArgs e)
{
if (FileUpload1.HasFile)
{
try
{
if (FileUpload.PostedFile.ContentType == "pdf")
{
string fileName = Path.GetFileName(FileUpload1.FileName);
FileUpload1.PostedFile.SaveAs(Server.MapPath("~/Upload/") + fileName);
Response.Redirect(Request.Url.AbsoluteUri);
}
else
Label1.Text = "PDF files only";
}
catch (Exceptionex)
{
Label1.Text = "Error during uploading the file";
}
}
}
请建议解决方案。
使用Path.GetExtension然后你可以有类似的东西
string fileExtension = Path.GetExtension(fileName);
fileExtension = fileExtension.ToLower();
string[] acceptedFileTypes = { ".docx", ".pdf" };
bool acceptFile = false;
for (int i = 0; i <= 1; i++)
{
if (fileExtension == acceptedFileTypes[i])
{
acceptFile = true;
}
}
if (!acceptFile)
{
Label1.Text = "You error message here";
return;
}
您现有的UploadFile方法位于右侧，但在您检查FileUpload.PostedFile.ContentType ，此属性包含上载文件的MIME类型。 PDF的正确MIME类型是application/pdf （如此问题中指定的;它是文件内的二进制数据，它使其成为PDF，而不仅仅是它具有扩展名'pdf'（顺便说一句，您还想宽松地使用.ToLowerInvariant用于比较，否则'PDF'文件扩展名不会被寻找'pdf'的东西所困住）。对于docx文件，在代码中查找的MIME类型是application/vnd.openxmlformats-officedocument.wordprocessingml.document （reference）。所以你的代码看起来像这样：
protected void UploadFile(object sender, EventArgs e)
{
// Build a list of whitelisted (acceptable) MIME types
// This list could be driven from a database or external source so you can change it without having to recompile your code
List<string> whiteListedMIMETypes = new List<string>();
whiteListedMIMETypes.Add("application/pdf");
whiteListedMIMETypes.Add("application/vnd.openxmlformats-officedocument.wordprocessingml.document");
if (FileUpload1.HasFile)
{
try
{
// Check the list to see if the uploaded file is of an acceptable type
if (whiteListedMIMETypes.Contains(FileUpload1.PostedFile.ContentType.ToLowerInvariant()))
{
string fileName = Path.GetFileName(FileUpload1.FileName);
FileUpload1.PostedFile.SaveAs(Server.MapPath("~/Upload/") + fileName);
Response.Redirect(Request.Url.AbsoluteUri);
}
else
Label1.Text = "Unacceptable file type";
}
catch (Exception ex)
{
Label1.Text = "Error during uploading the file";
}
}
}
作为一个普遍的观点，你不应该仅仅依靠文件名的扩展名来确定它的类型 - 用户可以以他们想要的方式重命名文件和扩展名，但是如果我将FileStealingVirus.exe重命名为FileStealingVirus.pdf ，那么文件仍然是一个文件窃取病毒，而不是PDF文件。 如果我知道你只是检查上传文件的扩展名，我知道我可以通过伪装成PDF来上传我的病毒，然后我可以窃取你的文件！
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