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

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

XML/XHTML 代码

<!--<br /> <br /> Code highlighting produced by Actipro CodeHighlighter (freeware)<br /> http://www.CodeHighlighter.com/<br /> <br /> --> < 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：

ASPX 代码

<!--<br /> <br /> Code highlighting produced by Actipro CodeHighlighter (freeware)<br /> http://www.CodeHighlighter.com/<br /> <br /> --> <% @ 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" /> &nbsp;&nbsp;
< asp:Button ID ="btnPost" runat ="server" Text ="上传" OnClick ="btnPost_Click" />
</ td >
</ tr >
</ table >
</ div >
</ form >
</ body >
</ html >

C# 代码

<!--<br /> <br /> Code highlighting produced by Actipro CodeHighlighter (freeware)<br /> http://www.CodeHighlighter.com/<br /> <br /> --> 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 ), "" , @" <script>alert('不能添加已经添加过的文件！')</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 ), "" , @" <script>alert('上传成功！')</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。

ASPX 代码

<!--<br /> <br /> Code highlighting produced by Actipro CodeHighlighter (freeware)<br /> http://www.CodeHighlighter.com/<br /> <br /> --> <% @ 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" >
< asp:Button ID ="btnAdd" runat ="server" Text ="添加文件" OnClick ="btnAdd_Click" /> &nbsp;&nbsp;
< asp:Button ID ="btnDelete" runat ="server" Text ="删除文件" OnClick ="btnDelete_Click" /> &nbsp;&nbsp;
< asp:Button ID ="btnPost" runat ="server" Text ="完成上传" OnClick ="btnPost_Click" />
</ td >
</ tr >
</ table >
</ form >
</ body >
</ html >

C# 代码

<!--<br /> <br /> Code highlighting produced by Actipro CodeHighlighter (freeware)<br /> http://www.CodeHighlighter.com/<br /> <br /> --> 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 ), "" , @" <script>alert('总上传的文件超过了大小设置1024 * 1024 ！')</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 ), "" , @" <script>alert('不能添加已经添加过的文件！')</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 ), "" , @" <script>alert('上传成功！')</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);
}
}
}
}
}