Struts 1 学习笔记-3-2（JSTL核心标签库测试）

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#测试 #struts #import #c #hashmap #action

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本文详细介绍并演示了JavaServer Pages Standard Tag Library (JSTL) 核心标签的使用方法，包括c:out、c:set、c:remove、c:if、c:choose、c:when、c:otherwise、c:forEach等标签的功能与应用实例。

1.引入以下两个jar包

2.按惯例，先上struts-config.xml，（其中包含了我上一个EL测试的action）

<?xml version="1.0" encoding="ISO-8859-1" ?>

<!DOCTYPE struts-config PUBLIC

"-//Apache Software Foundation//DTD Struts Configuration 1.2//EN"

"http://jakarta.apache.org/struts/dtds/struts-config_1_2.dtd">

<struts-config>

<action-mappings>

</action>

</action>

</action-mappings>

<message-resources parameter="MessageResources" />

</struts-config>

3.接下来JSTLCoreAction.java：

package com.codedestiny.struts;

import java.util.ArrayList;

import java.util.HashMap;

import java.util.List;

import java.util.Map;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import org.apache.struts.action.Action;

import org.apache.struts.action.ActionForm;

import org.apache.struts.action.ActionForward;

import org.apache.struts.action.ActionMapping;

public class JSTLCoreAction extends Action {

public ActionForward execute(ActionMapping mapping, ActionForm form, HttpServletRequest request, HttpServletResponse response) throws Exception {

request.setAttribute("hello", "Hello World");

request.setAttribute("cd", "<font color='red' size='6'>成都欢迎大家</font>");

request.setAttribute("v1", 10);

request.setAttribute("v2", 20);

List<User> users = new ArrayList<User>();

Group relatedGroup = new Group();

relatedGroup.setName("Xihua Univercity");

for(int i=1; i<10; i++) {

User u = new User();

u.setUsername("user" + i);

u.setAge(20 + i);

u.setRelatedGroup(relatedGroup);

users.add(u);

}

Map<String, Integer> hashMap = new HashMap<String, Integer>();

hashMap.put("key1", 1);

hashMap.put("key2", 2);

hashMap.put("key3", 3);

hashMap.put("key4", 4);

request.setAttribute("map", hashMap);

request.setAttribute("users", users);

request.setAttribute("tokenstr", "1,2,3,4,5");

return mapping.findForward("success");

}

4.展示页面jstlcore.jsp：

<%@ page language="java" import="java.util.*" pageEncoding="GB18030"%>

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

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">

<html>

<head>

</head>

<body>

<h1>JSTL核心库标签测试</h1>

<hr>

hello(default) : <c:out value="${hello}"></c:out><br>

b(default value) : <c:out value="${b}" default="no value"></c:out><br>

b(default value) : <c:out value="${b}">no value</c:out><br>

cd(default) : <c:out value="${cd}"></c:out><br>

cd(escapeXml=true) : <c:out value="${cd}" escapeXml="true"></c:out><br>

cd(escapeXml=false) : <c:out value="${cd}" escapeXml="false"></c:out><br>

<hr>

<li>测试c:set, c:remove</li><br>

<c:set var="temp" value="123"></c:set>

temp : ${ temp } <br>

<c:remove var="temp"/>

temp : ${ temp } <br>

<hr>

<li>测试条件控制标签c:if</li><br>

<c:if test="${v1 < v2}" var="boolean">

v1 < v2 ? ${boolean} <br>

</c:if>

<hr>

<li>测试条件控制标签c:choose, c:when, c:otherwise</li><br>

<c:choose>

<c:when test="${v1 < v2}">

v1 < v2 <br>

</c:when>

<c:otherwise>

v1 > v2 <br>

</c:otherwise>

</c:choose>

<hr>

<li>测试循环访问标签c:forEach</li><br>

<tr>

</tr>

<c:choose>

<c:when test="${empty users}">

<tr><td colspan="3">没有相关数据</td></tr>

</c:when>

<c:otherwise>

<c:forEach items="${users}" var="user">

<tr>

<td>${user.username}</td>

<td>${user.relatedGroup.name}</td>

</tr>

</c:forEach>

</c:otherwise>

</c:choose>

</table>

<hr>

<li>测试循环访问标签c:forEach中varStatus的用法</li><br>

<tr>

</tr>

<c:choose>

<c:when test="${empty users}">

<tr><td colspan="3">没有相关数据</td></tr>

</c:when>

<c:otherwise>

<c:forEach items="${users}" var="user" varStatus="vs">

<c:choose>

<c:when test="${vs.count % 2 == 0}">

<td>${user.username}</td>

<td>${user.relatedGroup.name}</td>

</tr>

</c:when>

<c:otherwise>

<tr>

<td>${user.username}</td>

<td>${user.relatedGroup.name}</td>

<tr>

</c:otherwise>

</c:choose>

</c:forEach>

</c:otherwise>

</c:choose>

</table>

<hr>

<li>测试循环访问标签c:forEach中begin, end, step的用法</li><br>

<tr>

</tr>

<c:choose>

<c:when test="${empty users}">

<tr><td colspan="3">没有相关数据</td></tr>

</c:when>

<c:otherwise>

<c:forEach items="${users}" var="user" varStatus="vs" begin="1" end="8" step="2">

<c:choose>

<c:when test="${vs.count % 2 == 0}">

<td>${user.username}</td>

<td>${user.relatedGroup.name}</td>

</tr>

</c:when>

<c:otherwise>

<tr>

<td>${user.username}</td>

<td>${user.relatedGroup.name}</td>

<tr>

</c:otherwise>

</c:choose>

</c:forEach>

</c:otherwise>

</c:choose>

</table>

<hr>

<li>测试循环访问标签c:forEach,输出一个map</li><br>

<c:forEach items="${map}" var="v">

<c:out value="${v.key}"/> = <c:out value="${v.value}"/><br>

</c:forEach>

<hr>

<li>测试循环访问标签c:forEach,普通标签</li><br>

<c:forEach begin="0" end="5">

aaa<br>

</c:forEach>

<hr>

<li>测试循环控制标签c:fortokens</li><br>

<c:forTokens items="${tokenstr}" delims="," var="v">

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

</c:forTokens>

</body>

</html>

5.最后来几张测试结果的截图：