el | 易学教程

JSTL c:if does not recognize String inside ${} and causes EL syntax error

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问题 Why are the "POST" and "submit" parts of this code highlighted in a different color in my IDE? Also the syntax highlighter here doesn't highlight them in same color. <c:if test="${"POST".equalsIgnoreCase(pageContext.request.method) && pageContext.request.getParameter("submit") !=null}"> </c:if> Does that mean that EL does not recognize the string and so gives me an EL syntax error? How can I solve this? 回答1: Inside the <c:if> , your test attribute is a also a string, which is set with double

JSTL c:if does not recognize String inside ${} and causes EL syntax error

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How to assign values for a list of some objects defined as variable with Spring Expression Language(Or the other expression languages you aware of)

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问题 In Spel, it is easy to assign some values for a List property. For example having object foo with a property defined as List, I usually do: SpelParserConfiguration config = new SpelParserConfiguration(true,true); ExpressionParser parser = new SpelExpressionParser(config); Foo foo = new Foo(); EvaluationContext context = new StandardEvaluationContext(foo); parser.parseExpression("barList[1].test='11111111'") .getValue(context); But what do you do for the case you want to assign values for a

How to assign values for a list of some objects defined as variable with Spring Expression Language(Or the other expression languages you aware of)

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Using EL variable of <c:set> inside Facelets <ui:repeat> tags

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问题 I have a Home . Each Home has a list of Room s. Each Room has zero or more Person s. I would like to count total persons of each home. But I can't add a new variable to record person count in any backing beans or entity. So I'd like to count it in the view only via <c:set> . My first attempt look like: <c:set var="personCount" value="${0}" /> <ui:repeat var="home" value="#{mybackingBean.homes}"> <ui:repeat var="room" value="#{home.rooms}"> ${personCount += room.persons.size()} </ui:repeat> <h

Can servlet attribute names contain a hyphen -?

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问题 Can servlet attribute names contain a hyphen - ? Because, I tried to retrieve the attributes from the request set in the doPost in my servlet, but the result is not what I'm looking for. In my servlet I have this : String X_USER = request.getParameter("X-User"); request.setAttribute("X-User", X_USER); String YYYY_YYYY = request.getParameter("Y_CODE"); request.setAttribute("Y-Code", YYYY_YYYY); In my JSP where I want to show these attributes I do this: <li>${X-User}</li> <li>${Y-Code}</li> The

How to escape double quotes in JSTL function / EL?

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问题 I need to change " to \" with JSTL replace function to use the string in input tag like: <input type="hidden" name="text" size="40" value="${text}"> If the ${text} has the " , the HTML will be broken. So I tried <input type="hidden" name="text" size="40" value="${fn:replace(text, "\"", "\\\""}"> and <input type="hidden" name="text" size="40" value="${fn:replace(text, '"', '\"'}"> but didn't worked. The page makes errors like org.apache.el.parser.ParseException: Encountered " "}" "} "" at line

JSTL与EL表达式（为空判断,集合长度）

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1、在jsp中引入标准函数声明 <%@ taglib uri=" http://java.sun.com/jsp/jstl/core " prefix="c"%> 2、若要判断集合的大小，则需要引入如下声明 <%@ taglib prefix="fn" uri=" http://java.sun.com/jsp/jstl/functions " %> 3、如何使用jstl判断集合是否为空 ${user}为集合,user为集合名 <c:if test="${empty user}">无信息!</c:if>为空 <c:if test="${!empty user}">其它</c:if>非空 4、如何取得集合的大小 ${fn:length(集合名<如果是session中的集合则应该加上sessionScope.键>)} ${fn:length(map)} 5、如何取得保存在session中的对象? ${sessionScope.键.对象属性} 6、varStatus显示循环变量的状态例:<tag:forEach var="currentFood" items="${sessionScope.foods}" varStatus="status" <tag:if test="${status%2==1}"> ..................... </tag:if> </tag

Evaluating JSP EL without a Servlet container

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问题 Here's what I want to do: Map<String, Object> model = new Hashmap<String, Object>(); model.put("a", "abc"); model.put("b", new Hashmap<String, Object>()); model.get("b").put("c", "xyz"); String el = "A is ${a} and C is ${b.c}"; assertEquals(elEval(el, model), "A is abc and C is xyz"); Is this possible? 回答1: Yes , it is possible , you can refer to this link for more information . As you can see , in order to use the EL expression standalone , you would have to implement several classes such as

EL+servlet+jsp实现简单的投票程序版本二

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在该项目版本一中，主要涉及最基本的java web基础知识。本篇博文仍然是基本知识，不过在版本一中，所有投票不计名不限定ip，bug很多。在版本二中有所改善，主要在投票之前加上了登录这一块，如果该用户名已经投票则自动跳转投票结果页面。如果您对EL表达式不熟悉，请阅读我前面相关EL的基础博文 EL表达式（一）： http://my.oschina.net/passer007/blog/608675 EL表达式（二）： http://my.oschina.net/passer007/blog/610221 EL表达式中的隐含对象： http://my.oschina.net/passer007/blog/610380 如果你在翻阅版本二之前还没有阅读版本一请移步版本一，因为版本一中出现的版本二中不需要修改的页面我将不会在此博文中粘贴出来： EL+servlet+jsp实现简单的投票程序版本一： http://my.oschina.net/passer007/blog/610513 写在前面的tips：由于是简单的投票程序，我在验证用户是否投票这一过程中直接采用用户名验证，不需要取数据库再验证用户密码，需要验证密码的同学可以自己完善程序。在版本二中由于验证用户名，必须需要建立数据库连接，一下是连接数据库的基础代码： package com.zhong.el; import java