java:
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
System.out.println(basePath);
%>
EL: ${pageContext.request.scheme}${'://'}${pageContext.request.serverName}${':'}${pageContext.request.serverPort}${pageContext.request.contextPath}