我应该如何在jsp页面中获取根文件夹路径

<%
String rootPath = request.getContextPath();
%>

<c:set var="rootPath" value="${pageContext.request.contextPath}" />

<c:url var="rootPath" value="/" />

<base href="<%=request.getContextPath()%>/" />

<%
String rootPath = request.getContextPath();
String filePath = "/images/logo.png";
String fileUrl = rootPath + filePath;
%>