feat(structs): add OGNL binding lab and deepen interceptor learning page

src/main/java/com/example/struts2/OgnlLabAction.java

@@ -0,0 +1,71 @@
+package com.example.struts2;
+
+import com.opensymphony.xwork2.ActionSupport;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+import java.util.stream.Collectors;
+
+public class OgnlLabAction extends ActionSupport {
+    private String keyword;
+    private Integer minAge;
+    private DemoUser user = new DemoUser();
+    private List<String> tags = new ArrayList<>();
+    private List<DemoUser> users;
+    private List<DemoUser> filteredUsers;
+
+    public String execute() {
+        loadUsers();
+        filteredUsers = users;
+        return SUCCESS;
+    }
+
+    public String bind() {
+        loadUsers();
+        filteredUsers = users.stream()
+                .filter(u -> keyword == null || keyword.isBlank() || u.getName().contains(keyword) || u.getEmail().contains(keyword))
+                .filter(u -> minAge == null || u.getAge() >= minAge)
+                .collect(Collectors.toList());
+        return SUCCESS;
+    }
+
+    private void loadUsers() {
+        users = Arrays.asList(
+                new DemoUser("张三", "zhangsan@example.com", 22),
+                new DemoUser("李四", "lisi@example.com", 28),
+                new DemoUser("王五", "wangwu@example.com", 34),
+                new DemoUser("赵六", "zhaoliu@example.com", 19)
+        );
+    }
+
+    public static class DemoUser {
+        private String name;
+        private String email;
+        private Integer age;
+
+        public DemoUser() {}
+        public DemoUser(String name, String email, Integer age) {
+            this.name = name;
+            this.email = email;
+            this.age = age;
+        }
+        public String getName() { return name; }
+        public void setName(String name) { this.name = name; }
+        public String getEmail() { return email; }
+        public void setEmail(String email) { this.email = email; }
+        public Integer getAge() { return age; }
+        public void setAge(Integer age) { this.age = age; }
+    }
+
+    public String getKeyword() { return keyword; }
+    public void setKeyword(String keyword) { this.keyword = keyword; }
+    public Integer getMinAge() { return minAge; }
+    public void setMinAge(Integer minAge) { this.minAge = minAge; }
+    public DemoUser getUser() { return user; }
+    public void setUser(DemoUser user) { this.user = user; }
+    public List<String> getTags() { return tags; }
+    public void setTags(List<String> tags) { this.tags = tags; }
+    public List<DemoUser> getUsers() { return users; }
+    public List<DemoUser> getFilteredUsers() { return filteredUsers; }
+}

src/main/resources/struts.xml

@@ -64,6 +64,14 @@
         <action name="interceptor" class="com.example.struts2.InterceptorDemoAction">
             <result>/interceptor-demo.jsp</result>
         </action>
+
+        <action name="ognl" class="com.example.struts2.OgnlLabAction">
+            <result>/ognl-lab.jsp</result>
+        </action>
+
+        <action name="ognl_bind" class="com.example.struts2.OgnlLabAction" method="bind">
+            <result>/ognl-lab.jsp</result>
+        </action>
         
         <action name="interceptor_api" class="com.example.struts2.InterceptorDemoAction">
             <interceptor-ref name="apiStack"/>

src/main/webapp/index.jsp

@@ -61,6 +61,11 @@
             <p>从列表页到表单页，再到新增/编辑/删除，形成完整的 Struts2 业务流学习闭环。</p>
             <a href="user" class="btn green">进入 CRUD</a>
         </div>
+        <div class="card">
+            <h3>🧪 OGNL / 参数绑定实验</h3>
+            <p>可视化体验普通字段、嵌套对象、多选列表是如何被 Struts2 自动绑定到 Action 的。</p>
+            <a href="ognl" class="btn purple">进入实验室</a>
+        </div>
     </div>
 
     <div class="timeline">

src/main/webapp/interceptor-demo.jsp

@@ -53,10 +53,29 @@
     <div class="card">
         <h3>🔗 拦截器链演示</h3>
         <p>当前使用: <code>customStack</code> (日志 + 计时 + 监控 + 默认栈)</p>
-        <a class="api-link" href="interceptor_api">使用 API 限流栈</a>
+        <a class="api-link" href="interceptor_api">切换到 API 限流栈</a>
+        <a class="api-link" href="interceptor">恢复默认栈</a>
         <p>API 栈包含: 日志 + 限流 + 验证 + 计时 + 默认栈</p>
+        <table>
+            <tr><th>拦截器</th><th>作用</th><th>你应该观察什么</th></tr>
+            <tr><td>LoggingInterceptor</td><td>记录请求进入/退出</td><td>看日志顺序，理解责任链</td></tr>
+            <tr><td>TimingInterceptor</td><td>统计执行耗时</td><td>看 executionTime 如何注入 request</td></tr>
+            <tr><td>MonitorInterceptor</td><td>累积 Action 调用统计</td><td>连续刷新看调用数增长</td></tr>
+            <tr><td>RateLimitInterceptor</td><td>限制频率</td><td>API 栈里观察限流触发</td></tr>
+            <tr><td>ValidationInterceptor</td><td>校验输入</td><td>思考错误应该在哪一层拦截</td></tr>
+        </table>
     </div>
     
+    <div class="card">
+        <h3>🧪 快速实验建议</h3>
+        <ul>
+            <li>先刷新当前页两次，看调用统计是否增加</li>
+            <li>再切到 <code>interceptor_api</code>，对比多了哪些拦截器</li>
+            <li>观察“先进入后退出”的洋葱模型</li>
+            <li>思考：如果你要加鉴权，应放在哪个拦截器位置最合理？</li>
+        </ul>
+    </div>
+
     <div class="card">
         <h3>📚 拦截器执行顺序</h3>
         <pre>

src/main/webapp/learn.jsp

@@ -62,6 +62,11 @@
             <p>通过用户管理体验列表页、表单页、重定向和状态更新。</p>
             <a class="btn btn-green" href="user">打开用户管理</a>
         </div>
+        <div class="card">
+            <h3>🧪 OGNL / 参数绑定实验</h3>
+            <p>通过真正可交互的表单观察 Struts2 的字段绑定、嵌套对象绑定和集合绑定。</p>
+            <a class="btn btn-purple" href="ognl">打开 OGNL 实验室</a>
+        </div>
     </div>
 
     <h2>📚 学习路径</h2>

src/main/webapp/ognl-lab.jsp

@@ -0,0 +1,83 @@
+<%@ page contentType="text/html;charset=UTF-8" language="java" %>
+<%@ taglib prefix="s" uri="/struts-tags" %>
+<!DOCTYPE html>
+<html>
+<head>
+    <meta charset="UTF-8">
+    <title>OGNL / 参数绑定实验室 - Struts2</title>
+    <style>
+        body { font-family: Arial, sans-serif; max-width: 1000px; margin: 40px auto; padding: 20px; background:#f7f8fa; }
+        h1 { color:#8e44ad; }
+        .card { background:#fff; border-radius:12px; padding:20px; margin:18px 0; box-shadow:0 4px 14px rgba(0,0,0,.06); }
+        .lab { background:#fff7e6; border-left:4px solid #fa8c16; padding:15px; border-radius:8px; margin:20px 0; }
+        .form-row { display:flex; gap:12px; flex-wrap:wrap; margin:10px 0; }
+        input, select { padding:10px; min-width:180px; }
+        button { background:#8e44ad; color:#fff; border:none; padding:10px 18px; border-radius:6px; cursor:pointer; }
+        table { width:100%; border-collapse:collapse; margin-top:12px; }
+        th, td { border:1px solid #ddd; padding:10px; text-align:left; }
+        th { background:#8e44ad; color:white; }
+        code { background:#f0f0f0; padding:2px 6px; border-radius:4px; }
+    </style>
+</head>
+<body>
+    <h1>🧪 OGNL / 参数绑定实验室</h1>
+
+    <div class="lab">
+        <strong>实验任务卡</strong>
+        <ul>
+            <li>输入关键字和最小年龄，观察 Struts2 如何自动绑定请求参数到 Action 字段</li>
+            <li>注意 <code>keyword</code>、<code>minAge</code>、<code>user.name</code> 这类命名会如何映射</li>
+            <li>观察页面里 <code>&lt;s:property&gt;</code>、<code>&lt;s:iterator&gt;</code> 如何读取 Action 中的数据</li>
+        </ul>
+    </div>
+
+    <div class="card">
+        <h3>参数过滤实验</h3>
+        <s:form action="ognl_bind" method="post">
+            <div class="form-row">
+                <s:textfield name="keyword" label="关键字" placeholder="例如：张 / example"/>
+                <s:textfield name="minAge" label="最小年龄" placeholder="例如：20"/>
+            </div>
+            <div class="form-row">
+                <s:textfield name="user.name" label="嵌套对象 user.name" placeholder="例如：测试用户"/>
+                <s:checkboxlist name="tags" label="兴趣标签" list="{'MVC','OGNL','Interceptor','JSP'}"/>
+            </div>
+            <button type="submit">执行绑定与过滤</button>
+        </s:form>
+    </div>
+
+    <div class="card">
+        <h3>绑定结果观察</h3>
+        <p>keyword = <code><s:property value="keyword" default="(空)"/></code></p>
+        <p>minAge = <code><s:property value="minAge" default="(空)"/></code></p>
+        <p>user.name = <code><s:property value="user.name" default="(空)"/></code></p>
+        <p>tags = <code><s:property value="tags" default="[]"/></code></p>
+    </div>
+
+    <div class="card">
+        <h3>过滤后的用户列表</h3>
+        <table>
+            <tr><th>姓名</th><th>邮箱</th><th>年龄</th></tr>
+            <s:iterator value="filteredUsers" var="u">
+                <tr>
+                    <td><s:property value="#u.name"/></td>
+                    <td><s:property value="#u.email"/></td>
+                    <td><s:property value="#u.age"/></td>
+                </tr>
+            </s:iterator>
+        </table>
+    </div>
+
+    <div class="card">
+        <h3>学习点</h3>
+        <ul>
+            <li><code>keyword</code> → 直接绑定到 Action 同名字段</li>
+            <li><code>user.name</code> → 绑定到嵌套对象属性</li>
+            <li><code>tags</code> → 多选值绑定到 <code>List&lt;String&gt;</code></li>
+            <li><code>&lt;s:iterator&gt;</code> 会遍历 Action 暴露出来的集合</li>
+        </ul>
+    </div>
+
+    <p><a href="learn">← 返回学习中心</a></p>
+</body>
+</html>