JSTL标签库详解：简化JSP编程的高效工具-优快云博客

本文链接：https://blog.youkuaiyun.com/PF_no_sad/article/details/119971727

JSTL标签库

JSTL标签库全称是 JSP Standard Tag Library jsp标准标签库。是一个不断完善的开放源代码的JSP标签库。
主要为了替代代码脚本

1.导入jar包
2.使用 taglib 指令引入标签库

<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>

core核心库使用

<c:set/>用法

<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<%--
  Created by IntelliJ IDEA.
  User: 26049
  Date: 2021/8/28
  Time: 17:46
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>$Title$</title>
</head>
<body>
    保存前：${ requestScope.abc}
    <c:set scope="request" var="abc" value="abcValue"/>
    保存后：${ requestScope.abc}
</body>
</html>

<c:if/>用法

<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<%--
  Created by IntelliJ IDEA.
  User: 26049
  Date: 2021/8/28
  Time: 17:46
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>$Title$</title>
</head>
<body>
    <c:if test="${ 12==12 }">
        <h1>12等于12</h1>
    </c:if>
</body>
</html>

<c:choose></c:choose>
<c:when></c:when>
<c:otherwise></c:otherwise>

<%--choose是外部标签--%>
<%--when相当于case--%>
<%--oherwise相当于default--%>

foreach标签遍历循环

<c:forEach begin="1" end="10" var="i"></c:forEach>

相当于

int i = 1; i < 10; i++

遍历数组

<c:forEach items="${ requestScope.arr }" var = "i"></c:forEach>