jstl處理遞歸問題

文章轉自：http://www.iteye.com/topic/1116588

需要兩個jsp頁面，一個是你要顯示樹的jsp頁面tree.jsp，一個是遞歸構造樹的頁面recursive.jsp 

顯示樹的jsp頁面，tree.jsp 

<%@ page language="java" contentType="text/html; charset=utf-8" pageEncoding="utf-8"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<div style=" float:left; display:block; margin:10px; overflow:auto; width:200px; height:300px; border:solid 1px #CCC; line-height:21px; background:#FFF;">
<ul class="tree">
<%@include file="recursive.jsp"%>
</ul>
</div>

遞歸構造樹的頁面recursive.jsp 

<%@ page language="java" contentType="text/html; charset=utf-8" pageEncoding="utf-8"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
       <li>
              <a href="main.html" target="navTab" rel="main">${menu.name}</a>
              <c:if test="${not empty menu.children}">
                     <ul>
                        <c:forEach var="menu" items="${menu.children}">
                            <c:set var="menu" value="${menu}" scope="request"/>
                        <jsp:include page="recursive.jsp"/>
                        </c:forEach>
                     </ul>
              </c:if>
       </li>

菜單Model,簡單的一個Bean,樹狀結構的數據模型 

public class MenuItem{
         private String name;
         private String url;
         private List<MenuItem> children = new ArrayList<MenuItem>();
         public MenuItem(String name,String url){
                this.name = name;
                this.url = url;
         }
         public void addChildMenu(MenuItem menu){
                this.children.add(menu);
         }
         .......
  }

構造模擬數據 

MenuItem menu31 = new MenuItem("三級菜單1", "url31");
MenuItem menu32 = new MenuItem("三級菜單2", "url32");
MenuItem menu33 = new MenuItem("三級菜單3", "url33");
MenuItem menu34 = new MenuItem("三級菜單4", "url34");
MenuItem menu35 = new MenuItem("三級菜單5", "url35");

MenuItem menu21 = new MenuItem("二級菜單1", "url21");
menu21.addChildMenu(menu31);
menu21.addChildMenu(menu32);
menu21.addChildMenu(menu33);

MenuItem menu22 = new MenuItem("二級菜單2", "url22");
menu22.addChildMenu(menu34);
menu22.addChildMenu(menu35);

MenuItem root = new MenuItem("根目錄", "root");
root.addChildMenu(menu21);
root.addChildMenu(menu22);

以上就是通過jstl標籤構造生成樹的全部代碼了 

最後生成的html代碼 

<div style=" float:left; display:block; margin:10px; overflow:auto; width:200px; height:300px; border:solid 1px #CCC; line-height:21px; background:#FFF;">
<ul class="tree">
       <li>
              <a href="main.html" target="navTab" rel="main">根目錄</a>
              <ul>
                     <li>
                           <a href="main.html" target="navTab" rel="main">二級菜單1</a>
                           <ul>
                                  <li><a href="main.html" target="navTab" rel="main">三級菜單1</a></li>
                                  <li><a href="main.html" target="navTab" rel="main">三級菜單2</a></li>
                                  <li><a href="main.html" target="navTab" rel="main">三級菜單3</a></li>
                           </ul>
                     </li>
                     <li>
                           <a href="main.html" target="navTab" rel="main">二級菜單2</a>
                           <ul>
                                  <li>
                                         <a href="main.html" target="navTab" rel="main">三級菜單4</a>
                                         <a href="main.html" target="navTab" rel="main">三級菜單5</a>
                                  </li>
                           </ul>
                     </li>
              </ul>
       </li>
</ul>
</div>