sharepoint 2010 获取文件小图标地址get document icon url

SPSite site = new SPSite("http://sharepoint-dev");

SPWeb web = site.OpenWeb("Documents");

string StrFileName = SPUtility.ConcatUrls

(

"http://sharepoint-dev:8002/Documents",

"http://sharepoint-dev:8002/Documents/DocLib/基本制度/交换机E.docx"

);

string docsicon = SPUtility.ConcatUrls("/_layouts/images/",SPUtility.MapToIcon(web, StrFileName,"", IconSize.Size16));

string IconUrl = docsicon;

输出的是"/_layouts/images/icdocx.png"