小峰servlet/jsp（6）jstl核心标签库

时间：2023-03-09 06:04:28
小峰servlet/jsp（6）jstl核心标签库

一、引入jstl

需要jstl.jar;standard.jar;

二、jstl核心标签库：

c:out   　　　　　　      内容输出标签;

c:set　　　　　　　      用来设置4种属性范围值的标签；

c:remove　　　　　   　用来删除指定范围中的属性；

c:catch　　　　　　　　用来处理程序中产生的异常；

c:if　　　　　　　　　　用来条件判断;

c:choose/c:when/c:otherwise 用来多条件判断;

c:forEach　　　　　　  用来遍历数组或者集合;

c:fortokens　　　　　　分隔输出;

c:import　　　　　　   导入页面;

c:url　　　　　　　　   生成一个url地址;

c:redirect　　　　　　  客户端跳转

c:out:

 <%@ page language="java" contentType="text/html; charset=UTF-8"

     pageEncoding="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>

 <%

     pageContext.setAttribute("people","张三");

 %>

 <h2><c:out value="${people}"></c:out></h2>

 <h2><c:out value="${people2}" default="某人"></c:out></h2>

 </body>

 </html>

c:set

 <body>

 <c:set var="people" value="张三" scope="request"></c:set>

 <h2><c:out value="${people}"></c:out></h2>

 <jsp:useBean id="people2" class="com.java1234.model.People" scope="page"></jsp:useBean>

 <c:set property="id" target="${people2 }" value="007"></c:set>

 <c:set property="name" target="${people2 }" value="王二小"></c:set>

 <c:set property="age" target="${people2 }" value="16"></c:set>

 <h2>编号：${people2.id }</h2>

 <h2>姓名：${people2.name }</h2>

 <h2>年龄：${people2.age }</h2>

 </body>

c:remove:

 <body>

 <c:set var="people" value="张三" scope="request"></c:set>

 <h2><c:out value="${people}" default="没人啊"></c:out></h2>

 <c:remove var="people" scope="request"/>

 <h2><c:out value="${people}" default="没人啊"></c:out></h2>

 </body>

c:catch:

 <body>

 <c:catch var="errMsg">

     <%

         int a=1/0;

     %>

 </c:catch>

 <h2>异常信息：${errMsg }</h2>

 </body>

小峰servlet/jsp（6）jstl核心标签库

c:if:

 <body>

 <jsp:useBean id="people" class="com.java1234.model.People" scope="page"></jsp:useBean>

 <c:set property="id" target="${people }" value="007"></c:set>

 <c:set property="name" target="${people }" value="王二小"></c:set>

 <c:set property="age" target="${people }" value="16"></c:set>

 <c:if test="${people.name=='王二小' }" var="r" scope="page">

     <h2>是王二小</h2>

 </c:if>

 <c:if test="${people.age<18 }">

     <h2>是未成年</h2>

 </c:if>

 </body>

c:choose/c:when/c:otherwise:  多条件判断:

 <body>

 <jsp:useBean id="people" class="com.java1234.model.People" scope="page"></jsp:useBean>

 <c:set property="id" target="${people }" value="007"></c:set>

 <c:set property="name" target="${people }" value="王二小"></c:set>

 <c:set property="age" target="${people }" value="19"></c:set>

 <c:choose>

     <c:when test="${people.age<18 }">

         <h2>小于18</h2>

     </c:when>

     <c:when test="${people.age==18 }">

         <h2>等于18</h2>

     </c:when>

     <c:otherwise>

         <h2>大于18</h2>

     </c:otherwise>

 </c:choose>

 </body>

c:forEach:

 <%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>

 <%@ page import="com.java1234.model.*"%>

 <%@ page import="java.util.*"%>

 <%@ 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>

 <%

     String dogs[]={"小黑","小黄","小白","小小"};

     pageContext.setAttribute("dogs",dogs);

 %>

 <c:forEach var="dog" items="${dogs }">

     ${dog }

 </c:forEach>

 <hr/>

 <c:forEach var="dog" items="${dogs }" step="2">

     ${dog }

 </c:forEach>

 <hr/>

 <c:forEach var="dog" items="${dogs }" begin="1" end="2"><!--begin end是索引值-->

     ${dog }

 </c:forEach>

 <hr/>

 <%

     List<People> pList=new ArrayList<People>();

     pList.add(new People(1,"张三",10));

     pList.add(new People(2,"李四",20));

     pList.add(new People(3,"王五",30));

     pageContext.setAttribute("pList",pList);

 %>

 <table>

     <tr>

         <th>编号</th>

         <th>姓名</th>

         <th>年龄</th>

     </tr>

     <c:forEach var="p" items="${pList }">

         <tr>

             <td>${p.id }</td>

             <td>${p.name }</td>

             <td>${p.age }</td>

         </tr>

     </c:forEach>

 </table>

 </body>

 </html>

小峰servlet/jsp（6）jstl核心标签库

c:forTokens: 分隔输出：

 <body>

 <%

     String str1="www.java1234.com";

     String str2="张三，李四，王五";

     pageContext.setAttribute("str1",str1);

     pageContext.setAttribute("str2",str2);

 %>

 <c:forTokens items="${str1 }" delims="." var="s1">

     ${s1 }

 </c:forTokens>

 <hr/>

 <c:forTokens items="${str2 }" delims="，" var="s2">

     ${s2 }

 </c:forTokens>

 </body>

c:import: 导入页面; 有点像jsp include：

 <body>

 <c:import url="c_forEach.jsp"></c:import>

 <c:import url="c_if.jsp"></c:import>

 </body>

c:url：

 <body>

 <c:url value="http://www.baidu.com" var="url">

     <c:param name="name" value="xiaoming"></c:param>

     <c:param name="age" value="26"></c:param>

 </c:url>

 <a href="${url }">百度</a>

 </body>

c:redirect 客户端跳转：

 <body>

 <c:redirect url="target.jsp">

     <c:param name="name" value="xiaoming"></c:param>

     <c:param name="age" value="26"></c:param>

 </c:redirect>

 </body>

 target.jsp:

 <body>

 <h2>姓名：${param.name }</h2>

 <h2>年龄：${param.age }</h2>

 </body>

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