JAVA_Web JSTL_Core标签库使用

c:out

c:if

用法：

    <c:if test="">
<%--        标签体--%>
    </c:if>
  • 如果test的计算结果为true,则执行标签体
  • 否则，不执行

c:choose

用法：

    <c:choose>
        <c:when test="">
            <%--        标签体--%>
        </c:when>

        <c:otherwise>
            <%--        标签体--%>
        </c:otherwise>
    </c:choose>
  • 如果when里面的test的计算结果为true,则该执行标签体
    • 否则，不执行
  • 如果全部when的条件都达不到，则输出otherwise的标签体

使用样例：

<%--
  Created by IntelliJ IDEA.
  User: WangWenZheng
  Date: 2022/5/25
  Time: 17:33
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>
<html>
<head>
    <title>Title</title>
</head>
<body>
    <c:choose>
        <c:when test="${empty param.username}">
            unKnown user.
        </c:when>

        <c:when test="${param.username=='itcast'}">
            ${param.username} is manager.
        </c:when>
        <c:otherwise>
            ${param.username} is employee.
        </c:otherwise>
    </c:choose>
</body>
</html>

c:forEach

用法：

    <c:forEach var="varname" items="collection" [begin="" end="" step=""] >
    </c:forEach>

var:当前迭代到的元素的数据
items：用于迭代的集合对象
begin=""迭代的起始位置（默认从0开始）
end=""迭代的终止位置（包含该位置）
step=""步长
使用样例：

<%@ page import="java.util.HashMap" %>
<%@ page import="java.util.Map" %><%--
  Created by IntelliJ IDEA.
  User: WangWenZheng
  Date: 2022/5/25
  Time: 19:04
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>
<html>
<head>
    <title>Title</title>
</head>
<body>
    <%
        String[] fruits={"apple","orange","grange" ,"banana"};
    %>
    <br/>
<c:forEach var="name" items="<%=fruits%>">
    ${name}<br>
</c:forEach>
    <%
        Map userMap=new HashMap();
        userMap.put("Tom","123");
        userMap.put("Make","1234");
        userMap.put("Lina","12345");
        userMap.put("Tom2","123");
        userMap.put("Make2","1234");
        userMap.put("Lina2","12345");
    %>
    <hr/>
    <br>
    <c:forEach var="entry" items="<%=userMap%>" >
        ${entry.key} &nbsp;${entry.value} <br>
    </c:forEach>
    <hr/>
    <br>
    <c:forEach var="entry" items="<%=userMap%>" begin="1" end="5" step="2" >
        ${entry.key} &nbsp;${entry.value} <br>
    </c:forEach>
</body>
</html>

c:param 和 c:url

posted @ 2022-05-25 19:26  kingwzun  阅读(28)  评论(0)    收藏  举报