<%@ page language="java" contentType="text/html; charset=UTF-8"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
<c:choose>
<c:when test="${ param.action }">
when 标签的输出
</c:when>
<c:otherwise>
otherwise 标签的输出
</c:otherwise>
</c:choose>
</body>
</html>
<c:choose/>、<c:when/>、<c:otherwise/>标签
原文：http://www.cnblogs.com/Nickzerui/p/4546645.html