你好快乐少年，
微软已经提供AjaxToolKit.dll，你可以使用AjaxFileUpload控件实现你所描述的功能,你可以参考：http://www.asp.net/ajaxLibrary/AjaxControlToolkitSampleSite/ajaxFileUpload/ajaxFileUpload.aspx
Happy Chen (Pactera Technologies Inc) Happy Chen<br/> MSDN Community Support | <a href="mailto:msdnmg@microsoft.com">Feedback to us</a><br/> <a href="http://blogs.msdn.com/b/win8devsupport/"><font color="red">Develop
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