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

piperzero · 发表于 2013-1-29 09:22:00

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
<httpRuntime executionTimeout="90" maxRequestLength="2097151" useFullyQualifiedRedirectUrl="false" requestLengthDiskThreshold="8192"/>
（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"  />                   <asp:Button ID="btnPost" runat="server" Text="上传"  />             </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"  />             <asp:Button ID="btnDelete" runat="server" Text="删除文件"  />             <asp:Button ID="btnPost" runat="server" Text="完成上传"  />          </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);             }          }       } }}

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