1.在jsp文件中引用
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
2.jstl常用标签的使用
1)choose
相当于switch
<body>
<%
Rat rat=new Rat();
rat.setName("Cally");
rat.setAge(10);
request.setAttribute("rat1", rat);
%>
<c:choose>
<c:when test="${rat1.age==7 }">
老鼠年纪为7
</c:when>
<c:when test="${rat1.age==8 }">
老鼠年纪为8
</c:when>
<c:when test="${rat1.age==10 }">
老鼠年纪为10
</c:when>
</c:choose>
</body>
forEach
<%
Map map=new HashMap();
map.put("aa", "宝玉");
map.put("cc", "黛玉");
request.setAttribute("persons", map);
%>
<c:forEach items="${persons }" var="per">
key=${per.key } value=${per.value}
</c:forEach>
if
<body>
<%
request.setAttribute("a", "hello");
Rat rat=new Rat();
rat.setName("小宝");
rat.setAge(5);
request.setAttribute("rat1", rat);
%>
<c:if test="${a=='hello' }">
ok!
</c:if>
<c:if test="${a!='hello' }">
no ok!
</c:if>
<c:if test="${rat1.age>3 }">
老鼠年纪大于3岁
</c:if>
</body>
out
<!-- 同时出现多个域对象，pageContext的优先级最高
pageContext=>request=>session=>application
-->
<%
//request.setAttribute("abc", "<a href='http://www.baidu.com'>百度</a>");
//session.setAttribute("abc", "你好1");
//application.setAttribute("abc", "你好2");
//pageContext.setAttribute("abc", "你好3");
//将user初始化后，当做域对象
User user=new User();
user.setName("Cally");
user.setAge(30);
request.setAttribute("user1", user);
%>
<!-- escapXml 用于指定是否按照html样式显示，默认true，表示文本，false为html格式 -->
<c:out value="${abc}" escapeXml="false"></c:out>
<!-- 将user1对象中的值取出来，调用了对象的get方法 -->
<c:out value="${ user1.age}"></c:out>
</body>
set
<body>
<!-- 等价于
request.setAttrbute("abc","中国,北京");
-->
<c:set var="abc" value="中国,北京" scope="request"></c:set>
<c:out value="${abc} "></c:out>
<c:remove var="abc"/>
<c:out value="${abc}" default="没有了"></c:out>
</body>