标签：
JSTL全名为JavaServer Pages Standard Tag Library 主要提供给JavaWeb开发人员一个标准通用的标签函数库.
Web程序开发人员能够利用JSTL和EL来开发Web程序,取代传统直接在页面上嵌入Java程序（Scripting）的做法，以提高程序的可读性,维护性和方便性.
需要引入的jar
jstl.jar
standard.jar
标签函数库主要分为5大类：
1.核心标签库(Core tag library)
2.I18N格式标签库(I18N-capable formatting tag library)
3.SQL标签库(SQL tag library)
4.XML标签库(XML tag library)
5.函数标签库(Functions tag library)
最常用的是 核心标签库
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<c:out>
与el类似，比el更强大，能够对敏感的字符进行转换
<% request.setAttribute("book", "<<book>>"); %> <br> book:${requestScope.book} <br> <c:out value="${requestScope.book }"></c:out>
book:<>
<<book>>
通过查看源文件，<c:out>会将敏感字符自动转义
<br> book:<<book>> <br> <<book>> <br><br>
<c:out value="${requestScope.book }" escapeXml="false"></c:out>
设置escapeXml="false" 默认不进行转义
<c:out value="${requestScope.book }" default="booktitle"></c:out>
当从域中没找到book时，取默认值
<c:set var="name" value="java" scope="page"></c:set>
<%--
pageContext.setAttribute("name", "java");
--%>
name:${pageScope.name }
使用<c:set>向指定域对象中赋值，类似于setAttribute
value中可以放EL表达式
<c:set var="subject" value="${param.subject }" scope="session"></c:set>
subject:${sessionScope.subject }
使用<c:set>为javaBean赋值
<% Customer cust = new Customer(); cust.setId(1001); request.setAttribute("cust", cust); %> ID:${requestScope.cust.id } <br> <c:set target="${requestScope.cust }" property="id" value="${param.id }"></c:set> ID:${requestScope.cust.id }
使用<c:remove>可以移除指定域对象中的指定属性
<c:set value="1997-1-1" var="date" scope="session"></c:set>
<c:out value="${sessionScope.date }"></c:out>
<br>
<c:remove var="date" scope="session"/>
date:${sessionScope.date }
<br><br>
JSTL 流程控制
<c:if> 仅有if,没有else，但可以把判断的结果储存起来，以备之后使用
<c:set value="20" var="age" scope="request"></c:set>
<c:if test="${requestScope.age>18 }">成年了</c:if>
<br>
<c:if test="${param.age>18 }" var="isAdult" scope="request"></c:if>
isAdult:<c:out value="${requestScope.isAdult }"></c:out>
<br><br>
<c:choose>只能当做<c:when>,<c:otherwise>的子标签
在同一个<c:choose>中时,<c:when>必须在<c:otherwise>之前
<c:when>必须有test属性
在同一个<c:choose>时,<c:otherwise>必须是最后一个标签
<c:choose>
<c:when test="${param.age>60 }">老年</c:when>
<c:when test="${param.age>35 }">中年</c:when>
<c:when test="${param.age>18 }">青年</c:when>
<c:otherwise>未成年</c:otherwise>
</c:choose>
<br><br>
JSTL迭代操作
<c:forEach>,<c:forTokens>
遍历一个Collection，遍历数组同Collection
<% List<Customer> custs = new ArrayList<Customer>(); custs.add(new Customer(1001,"AA","aa@java.com")); //index:0 custs.add(new Customer(1002,"BB","bb@java.com")); custs.add(new Customer(1003,"CC","cc@java.com")); custs.add(new Customer(1004,"DD","dd@java.com")); custs.add(new Customer(1005,"EE","ee@java.com")); custs.add(new Customer(1006,"FF","ff@java.com")); request.setAttribute("customers", custs); %> <c:forEach items="${requestScope.customers }" var="custs" varStatus="status"> ${status.index},${status.count},${status.first},${status.last}:${custs.id }:${custs.name }:${custs.email }<br> </c:forEach> <br><br>
遍历Map
<% Map<String,Customer> custsMap = new HashMap<String,Customer>(); custsMap.put("a", new Customer(1001,"AA","aa@java.com")); custsMap.put("b", new Customer(1002,"BB","bb@java.com")); custsMap.put("c", new Customer(1003,"CC","cc@java.com")); custsMap.put("d", new Customer(1004,"DD","dd@java.com")); custsMap.put("e", new Customer(1005,"EE","ee@java.com")); custsMap.put("f", new Customer(1006,"FF","ff@java.com")); request.setAttribute("customers", custsMap); %> <c:forEach items="${requestScope.customers }" var="custs"> ${custs.key}-${custs.value.id }-${custs.value.name }-${custs.value.email }<br> </c:forEach> <br><br>
可以用来获取属性名称
<c:forEach items="${pageContext.session.attributeNames }" var="attrName">
${attrName }
</c:forEach>
<c:forTokens>处理字符串的,类似于String的split
<c:set value="a,b,c.d.e.f;g;h" var="test" scope="request"></c:set>
<c:forTokens items="${requestScope.test }" delims="," var="s">
${s }<br>
</c:forTokens>
a
b
c.d.e.f;g;h
标签：
原文地址：http://www.cnblogs.com/wq3435/p/5191570.html
