對於asp.net程式，我們應該儘可能的提供一個便捷的使用者介面，減少頁面回傳就是其中之一。
本文示範一次上傳多個檔案的方法，在用戶端可以隨意控制上傳檔案的個數，但是注意總檔案大小不能過大，否則會有異常拋出。至於解決大檔案上傳的方法已經超出本文的討論範圍。
這裡有一個要點大家不要忽略了，否則程式不能正常工作。
就是必須指定form的enctype="multipart/form-data" 屬性
代碼如下：
<%@ Page language="c#" Codebehind="MultiAttchments.aspx.cs" AutoEventWireup="false" Inherits="WebApplication3.MultiAttchments" %>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN" >
<HTML>
<HEAD>
<script>
function AddAttachments()
{
document.getElementById('attach').innerText = "繼續添加附件";
tb = document.getElementById('attAchments');
newRow = tb.insertRow();
newRow.insertCell().innerHTML = "<input name='File' size='50' type='file'> <input type=button value='刪除' onclick='delFile(this.parentElement.parentElement.rowIndex)'>";
}
function delFile(index)
{
document.getElementById('attAchments').deleteRow(index);
tb.rows.length > 0?document.getElementById('attach').innerText = "繼續添加附件":document.getElementById('attach').innerText = "添加附件";
}
</script>
</HEAD>
<body MS_POSITIONING="GridLayout">
<form id="form1" method="post" runat="server" enctype="multipart/form-data">
<div><table id="attAchments"></table></div><span><IMG src="icoAddFl.gif"> </span> <A id="attach" style="font-family:宋體;font-size:9pt;" title="如果您要發送多個附件，您只需多次點擊“繼續添加附件”即可, 要注意附件總量不能超過發送限制的大小。" onclick="AddAttachments();"
href="javascript:;" name="attach">添加附件</A>
<br><br><br><br><br><br>
<asp:Button id="btnSend" runat="server" Text=" 上傳 "></asp:Button>
</form>
</body>
</HTML>
private void btnSend_Click(object sender, System.EventArgs e)
{
StringBuilder sb = new StringBuilder();
int attCount = 0;
string filePath = "";
for(int i=0; i< Request.Files.Count; i++)
{
if(Request.Files[i].ContentLength > 0)
{
filePath = Request.Files[i].FileName;
sb.Append("Files" + attCount++ + ": " + filePath + "<br>");
Request.Files[0].SaveAs(Server.MapPath("./") + filePath.Substring(filePath.LastIndexOf("\\")+1));
}
}
sb.Insert(0, "you upload " + attCount + " files.<br>");
Response.Write(sb.ToString());
}
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