jsp中如何判断图片url是否有效

Question

想做一个如果图片url无效（或者说图片不存在），就显示暂无图片的图片

Answer 1

 <img src="../FileTypeimg/<%# getFileIcon( Eval("FileNam").ToString()) %>" align="middle"
                                    width="16" height="16" alt="文件类型" />#region 判断并显示上传资源是什么类型的文件显示其图标
        public string getFileIcon(string b)
        {
            String Ext = b;
            string _Icon = "other.gif";
            Ext = Ext.ToLower();
            Ext = Ext.Substring(Ext.LastIndexOf(".") + 1);
            if (("aspx,asax,ascx").Contains(Ext))
                return "aspx.gif";            if (("asp,asa,axd").Contains(Ext))
                return "asp.gif";            if (("cs,vb").Contains(Ext))
                return "CS.gif";            if (("html,htm,stml").Contains(Ext))
                return "html.gif";            if (("exe,mis,bat").Contains(Ext))
                return "exe.gif";            if (("swf,flv").Contains(Ext))
                return "flash.gif";            if (("doc,docx,wps").Contains(Ext))
                return "doc.gif";            if (("jpg").Contains(Ext))
                return "jpg.gif";            if (("rar").Contains(Ext))
                return "rar.gif";            if (("zip").Contains(Ext))
                return "zip.gif";            if (("pdf").Contains(Ext))
                return "pdf.gif";            if (("xls").Contains(Ext))
                return "xls.gif";            if (("mdb").Contains(Ext))
                return "mdb.gif";            if (("mp3,mp4,rm,mid,rmvb").Contains(Ext))
                return "mid.gif";            if (("txt").Contains(Ext))
                return "txt.gif";            if (("bmp").Contains(Ext))
                return "bmp.gif";            if (("gif").Contains(Ext))
                return "gif.gif";            if (("psd").Contains(Ext))
                return "psd.gif";            if (("ppt").Contains(Ext))
                return "ppt.gif";            if (("dll").Contains(Ext))
                return "dll.gif";            if (("sql").Contains(Ext))
                return "sql.gif";            if (("mdb").Contains(Ext))
                return "mdb.gif";            if (("xml").Contains(Ext))
                return "xml.gif";            if (("php").Contains(Ext))
                return "php.gif";            if (("config").Contains(Ext))
                return "config.gif";
            if (("js").Contains(Ext))
                return "js.gif";
            return _Icon;
        }
        #endregion我这个是上传之后对应各个类型的文件图片 默认也就是你说的暂无是other.gif.
自己修改下- -
或者可以利用三元运算符 来实现

Answer 2

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onerror="javascript:this.src='http://www.jb51.net/logos.gif'" />http://www.jb51.net/article/8796.htm