<c:forEach>标签属性的含义

本文深入解析<c:forEach>标签的用法,包括其关键属性及其支持的集合类型,并提供了实例演示。重点阐述了如何利用<c:forEach>实现不同迭代需求,覆盖数组、集合、枚举等数据结构。

<c:forEach var="name" items="expression" varStatus="name"<wbr></wbr>

<wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr> begin="expression" end="expression" step="expression"&gt;<span><wbr></wbr></span><br><br><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr> body content<span></span><span><wbr></wbr></span><br><br><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr> &lt;/c:forEach&gt;<span><wbr></wbr></span><br><br><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr> &lt;c:forEach&gt;标签具有以下一些属性:<span><wbr></wbr></span><br><br> l<wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr> var:迭代参数的名称。在迭代体中可以使用的变量的名称,用来表示每一个迭代变量。类型为String。<span><wbr></wbr></span><br><br> l<wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr> items:要进行迭代的集合。对于它所支持的类型将在下面进行讲解。<span><wbr></wbr></span><br><br> l<wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr> varStatus:迭代变量的名称,用来表示迭代的状态,可以访问到迭代自身的信息。<span><wbr></wbr></span><br><br> l<wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr> begin:如果指定了items,那么迭代就从items[begin]开始进行迭代;如果没有指定items,那么就从begin开始迭代。它的类型为整数。<span><wbr></wbr></span><br><br> l<wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr> end:如果指定了items,那么就在items[end]结束迭代;如果没有指定items,那么就在end结束迭代。它的类型也为整数。<span><wbr></wbr></span><br><br> l<wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr> step:迭代的步长。<span><wbr></wbr></span><br><br><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr> &lt;c:forEach&gt;标签的items属性支持Java平台所提供的所有标准集合类型。此外,您可以使用该操作来迭代数组(包括基本类型数组)中的元素。它所支持的集合类型以及迭代的元素如下所示:<span><wbr></wbr></span><br><br> l<wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr> java.util.Collection:调用iterator()来获得的元素。<span><wbr></wbr></span><br><br> l<wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr> java.util.Map:通过java.util.Map.Entry所获得的实例。<span><wbr></wbr></span><br><br> l<wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr> java.util.Iterator:迭代器元素。<span><wbr></wbr></span><br><br> l<wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr> java.util.Enumeration:枚举元素。<span><wbr></wbr></span><br><br> l<wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr> Object实例数组:数组元素。<span><wbr></wbr></span><br><br> l<wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr> 基本类型值数组:经过包装的数组元素。<span><wbr></wbr></span></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr>

以原生php模板而不是html模板改写下文 <!DOCTYPE html> <html> <head> <title>调试信息</title> <style> .debug-section { margin: 20px 0; padding: 15px; border: 1px solid #ddd; border-radius: 5px; background-color: #f9f9f9; } .debug-section h2 { margin-top: 0; color: #333; border-bottom: 1px solid #eee; padding-bottom: 10px; } .debug-item { margin-bottom: 15px; padding: 10px; background-color: #fff; border: 1px solid #eee; border-radius: 3px; } .debug-item pre { background-color: #f5f5f5; padding: 10px; border-radius: 3px; overflow-x: auto; } .empty-message { color: #999; font-style: italic; } </style> </head> <body> <h1>系统调试信息</h1> <!-- Session 数据 --> <div class="debug-section"> <h2>Session 数据</h2> {if empty($sessionData)} <p class="empty-message">Session is empty</p> {else} {foreach $sessionData as $name => $value} <div class="debug-item"> <strong>Session Name:</strong> {$name|htmlspecialchars}<br> <strong>Value:</strong> <pre>{$value|print_r|htmlspecialchars}</pre> </div> {/foreach} {/if} </div> <!-- 普通 Cookie 数据 --> <div class="debug-section"> <h2>普通 Cookie 数据</h2> {if empty($cookieData)} <p class="empty-message">No cookies found</p> {else} {foreach $cookieData as $name => $value} {if $name != 'waxx' || !is_array($value)} <div class="debug-item"> <strong>Cookie Name:</strong> {$name|htmlspecialchars}<br> <strong>Value:</strong> <pre>{$value|print_r|htmlspecialchars}</pre> </div> {/if} {/foreach} {/if} </div> <!-- 原站点数组形式 Cookie --> <div class="debug-section"> <h2>原站点数组形式 Cookie (waxx)</h2> {if empty($waxxCookie)} <p class="empty-message">No waxx cookies found</p> {else} {foreach $waxxCookie as $key => $value} <div class="debug-item"> <strong>Cookie Name:</strong> waxx[{$key|htmlspecialchars}]<br> <strong>Value:</strong> <pre>{$value|print_r|htmlspecialchars}</pre> </div> {/foreach} {/if} </div> </body> </html>
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