多附件上传

脚本
<script type="text/javascript" language="javascript">
    var count=0;
    function Check()
    {
       if(document.all.tbSendTo.value=="")
       {
           sAlert("请输入收件人地址！");
           return false;
       }
       else if(document.all.tbSubject.value=="")
       {
           sAlert("请输入邮件主题！");
           return false;
       }
        else if(document.all.tbContent.value=="")
       {
           sAlert("请输入邮件内容！");
           return false;
       }
       return true;
    }
   
    function CheckOptionsExists(filename,div)
    {
       var div=$("divAtt");
       var inputs=div.getElementsByTagName("input");
       for(i=0;i<inputs.length;i++)   
       {
          if(inputs[i].type=="file"&&inputs[i].value==filename)
          {
            return true;
          }
       }
       return false;
    }
   
   
    function AddFile()
    {
   
   // debugger;
        var file = $("File1");
        var div=$("divAtt");
        var add=$("Add");
        if(file.value == "")
        {
            sAlert("请选择文件!");
            return;
        }
       
        var inputs=div.getElementsByTagName("input");
       if(inputs.length>8)
       {
         sAlert("附件数量不得超过4个！");
         return;
       }
      
        var ary = file.value.split("\\");
        var filename = ary[ary.length-1];
        if(CheckOptionsExists(file.value,div))
        {
           
            sAlert("文件已经存在列表中!");
            file.value="";
           
        }
        else
        {
            file.style.display="none";
            file.id="filetemp"+count;
            file.name="filetemp"+count;
           
            add.removeChild(file);
        //文件上传隐藏
            var f = document.createElement("input");
            f.type = "file";
            f.name = "file";
            f.id="File1";
            f.className="button";
            add.appendChild(f);
            var a=document.createElement("input");
           a.type="button";
           a.value="删除";
            a.id="link"+count;
            a.name="link"+count;
            var temp=count;
            a.onclick=function () {
                            RemoveFile(temp);};
            a.className="button";
           
            //文件名
             var span=document.createElement("span");
              var newText1 = document.createTextNode(filename);
              span.appendChild(newText1);
            span.name="span"+count;
            span.id="span"+count;
            div.appendChild(span);
            // alert(span.value);
            div.appendChild(file);
           // alert(file.value);
            div.appendChild(a);
          
          //  alert(a.value);
          //  alert(div.childs.length)
            count++;
        }

      
    }
   
  
    function RemoveFile(id)
    {
   // debugger;
       var div=$("divAtt");     
       div.removeChild($("filetemp"+id));
       div.removeChild($("link"+id));
       div.removeChild($("span"+id));
       
    }
    </script>

form需要设置属性（enctype="multipart/form-data">）这样在服务器端才能取到文件
  <form id="form1" runat="server" enctype="multipart/form-data">
html
<table>
   <tr  class="table-content">
            <td class="table-title">附件：</td>
            <td>
                 <div id="Add"><input type="button" class="button" value="添加附件" onclick="AddFile()"/><input id="File1" class="button" type="file" name="File1" /></div>
               
                </td>
            </tr>
            <tr  class="table-content">
          
            <td colspan="2">
                <div id="divAtt"></div></td>
            </tr>
</table>

.cs后台
for (int i = 0; i < Request.Files.Count; i++)
{
   string name=Request.Files[i].FileName;
                if (name.Trim().Length <= 0)
                {
                    continue;
                }
}