FileUpload上传多文件时出现“无法访问已关闭的文件”错误的解决方法

来源：互联网发布：研究生论文查重数据库编辑：程序博客网时间：2024/06/10 03:42

在使用 public static ArrayList files 变量保存临时上传的文件时，当文件比较大时，会出现“无法访问已关闭的文件”错误，网上也有很多这样的问题，但都没有解决办法。在配置文件中增加

（属性“maxRequestLength”值必须在 0-2097151 范围内。）一行之后，可以解决部分问题，但也不能彻底解决。出现这样的问题的代码是这样写的：

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default3.aspx.cs" Inherits="admin_Default3" %><!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"> <div> <table> <tr> <td align="right"> 本地文件： </td> <td> <asp:FileUpload ID="fupFile" runat="server" CssClass="btn" Width="247px" Height="20px" onkeydown="event.returnValue=false;" onpaste="return false" /> </td> </tr> <tr> <td align="right"> 文件列表： </td> <td valign="top"> <asp:ListBox ID="lbxFile" runat="server" Height="145px" Width="245px" CssClass="txt"> </asp:ListBox> </td> </tr> <tr> <td colspan="5"> <asp:Button ID="btnAdd" runat="server" Text="添加" OnClick="btnAdd_Click" /> <asp:Button ID="btnPost" runat="server" Text="上传" OnClick="btnPost_Click" /> </td> </tr> </table> </div> </form></body></html>

using System;using System.Collections.Generic;using System.Linq;using System.Web;using System.Web.UI;using System.Web.UI.WebControls;using System.Collections;using System.IO;public partial class admin_Default3 : System.Web.UI.Page{ public static ArrayList files = new ArrayList(); protected void btnAdd_Click(object sender, EventArgs e) { if (fupFile.HasFile) { ListItem item = new ListItem(); item.Value = item.Text = fupFile.PostedFile.FileName; if (!lbxFile.Items.Contains(item)) { lbxFile.Items.Add(item); files.Add(fupFile); } else Page.ClientScript.RegisterClientScriptBlock(typeof(string), "", @"<mce:script type="text/javascript"></mce:script>"); } } protected void btnPost_Click(object sender, EventArgs e) { if (files.Count > 0) { if (!Directory.Exists(MapPath("../bodyissue/temp"))) Directory.CreateDirectory(MapPath("../bodyissue/temp")); foreach (FileUpload fup in files) { if (fup.HasFile) fup.SaveAs(MapPath("../bodyissue/temp") + "/" + fup.FileName);//无法访问已关闭的文件 } Page.ClientScript.RegisterClientScriptBlock(typeof(string), "", @"<mce:script type="text/javascript"></mce:script>"); } }}

要实现类似的功能，其实完全没有必要使用 static 变量，使用 static 变量，也会导致一些问题，因为 .NET 中 static 变量是所有线程共同使用的。下面的这个方法的代码，就解决这个问题。

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="MultiFileUpload.aspx.cs" Inherits="MultiFileUplaod" %><!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:HiddenField ID="allFileSize" runat="server" Value="0" /> <table> <tr> <td align="right"> 本地文件： </td> <td> <asp:FileUpload ID="FileUpload1" runat="server" /> </td> </tr> <tr> <td align="right"> 文件列表： </td> <td> <asp:ListBox ID="lbxFile" runat="server" Height="145px" Width="245px" CssClass="txt"> </asp:ListBox> </td> </tr> <tr> <td colspan="2" style="text-align: center" mce_style="text-align: center"> <asp:Button ID="btnAdd" runat="server" Text="添加文件" OnClick="btnAdd_Click" /> <asp:Button ID="btnDelete" runat="server" Text="删除文件" OnClick="btnDelete_Click" /> <asp:Button ID="btnPost" runat="server" Text="完成上传" OnClick="btnPost_Click" /> </td> </tr> </table> </form></body></html>

using System;using System.Collections.Generic;using System.Web;using System.Web.UI;using System.Web.UI.WebControls;using System.Collections;using System.IO;public partial class MultiFileUplaod : System.Web.UI.Page{ private String folder; protected void Page_Load(object sender, EventArgs e) { folder = Server.MapPath("~/temp"); if (!Directory.Exists(folder)) Directory.CreateDirectory(folder); } protected void btnAdd_Click(object sender, EventArgs e) { if (FileUpload1.HasFile) { String newFileName = folder + "/" + Guid.NewGuid().ToString() + Path.GetExtension(FileUpload1.FileName); int totalFileSize = Int32.Parse(allFileSize.Value); int fileSize = FileUpload1.PostedFile.ContentLength; //此处也可以限制单个文件的大小 if (totalFileSize + fileSize > 1024 * 1024) { Page.ClientScript.RegisterClientScriptBlock(typeof(string), "", @"<mce:script type="text/javascript"></mce:script>"); return; } FileUpload1.SaveAs(newFileName); ListItem item = new ListItem(); item.Text = FileUpload1.FileName; item.Value = newFileName; for (int i = 0; i < lbxFile.Items.Count; i++) { if (lbxFile.Items[i].Text.Equals(FileUpload1.FileName, StringComparison.InvariantCultureIgnoreCase)) { Page.ClientScript.RegisterClientScriptBlock(typeof(string), "", @"<mce:script type="text/javascript"></mce:script>"); return; } } totalFileSize += fileSize; allFileSize.Value = totalFileSize.ToString(); lbxFile.Items.Add(item); } } protected void btnPost_Click(object sender, EventArgs e) { //对上传的文件进行进一步处理，或者退出弹出窗口等操作 for (int i = lbxFile.Items.Count - 1; i > -1; i--) { lbxFile.Items.Remove(lbxFile.Items[i]); } Page.ClientScript.RegisterClientScriptBlock(typeof(string), "", @"<mce:script type="text/javascript"></mce:script>"); } protected void btnDelete_Click(object sender, EventArgs e) { for (int i = lbxFile.Items.Count - 1; i > -1; i--) { if (lbxFile.Items[i].Selected) { String value = lbxFile.Items[i].Value; lbxFile.Items.Remove(lbxFile.Items[i]); if (File.Exists(value)) { File.Delete(value); } } } }}