原创

java递归实现导航菜单

需求背景

由于项目需要将目录显示在首页导航上，并且实现菜单联动，如何实现呢？这就是今天我们要讲的内容。通过递归来实现无限极菜单。

代码实现

数据库结构是这样子的

后台代码

/** * MIT License * Copyright (c) 2018 haihua.liu * Permission is hereby granted, free of charge, to any person obtaining a copy * of this software and associated documentation files (the "Software"), to deal * in the Software without restriction, including without limitation the rights * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell * copies of the Software, and to permit persons to whom the Software is * furnished to do so, subject to the following conditions: * The above copyright notice and this permission notice shall be included in all * copies or substantial portions of the Software. * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE * SOFTWARE. */ package cn.liuhaihua.web.service.impl; import java.util.ArrayList; import java.util.List; import org.apache.commons.lang.StringUtils; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.stereotype.Service; import cn.liuhaihua.web.mapper.WpTermsMapper; import cn.liuhaihua.web.service.WpTermsService; import cn.liuhaihua.web.util.BusinessConstants; import cn.liuhaihua.web.vo.TermsVO; /** * @ClassName: WpTermsServiceImpl * @Description: 标签和分类服务类 * @author Liuhaihua * @date 2018年7月27日 * */ @Service public class WpTermsServiceImpl implements WpTermsService { @Autowired private WpTermsMapper wpTermsMapper; /** * @param taxonomy * @return * @see cn.liuhaihua.web.service.WpTermsService#getTerms(java.lang.String) */ @Override public List<TermsVO> getTerms(String taxonomy) { List<TermsVO> list = wpTermsMapper.queryTermListByTaxonomy(taxonomy); return list; } /** * @Title: getChild * @Description:递归查找子菜单 * @param @param id * @param @param rootTermsVO * @param @return 参数 * @return List<TermsVO> 返回类型 * @throws */ public List<TermsVO> getChild(String id, List<TermsVO> allList){ // 子菜单 List<TermsVO> childList = new ArrayList<>(); for (TermsVO TermsVO : allList) { // 遍历所有节点，将父菜单id与传过来的id比较 if (StringUtils.isNotBlank(TermsVO.getParent())) { if (TermsVO.getParent().equals(id)) { childList.add(TermsVO); } } } // 把子菜单的子菜单再循环一遍 for (TermsVO TermsVO : childList) { // 递归 TermsVO.setChild(getChild(TermsVO.getTermId(), allList)); } // 递归退出条件 if (childList.size() == 0) { return null; } return childList; } /** * @return * @see cn.liuhaihua.web.service.WpTermsService#getNavigate() */ @Override public List<TermsVO> getNavigate() { List<TermsVO> list =this.getTerms(BusinessConstants.category); // 最后的结果 List<TermsVO> resultList = new ArrayList<TermsVO>(); // 先找到所有的一级菜单 for (int i = 0; i < list.size(); i++) { // 一级菜单parent =0 if (list.get(i).getParent().equals("0")) { resultList.add(list.get(i)); } } // 为一级菜单设置子菜单，getChild是递归调用的 for (TermsVO termsVO : resultList) { termsVO.setChild(getChild(termsVO.getTermId(), list)); } return resultList; } }

前台代码

<@customTag method="navigate"> <#if navigate?? && navigate?size gt 0> <#list navigate as item> <#if item.child?exists && item.child?size gt 0> <li class="dropdown"> <a href="#" class="dropdown-toggle menu_a" data-toggle="dropdown" aria-expanded="false"> ${item.name?if_exists} </a> <ul class="dropdown-menu" role="menu"> <#list item.child as node> <li><a href="/type/${node.termId?if_exists}" title="点击查看《${node.name?if_exists}》的文章">${node.name?if_exists}</a></li> </#list> </ul> </li> <#else> <li><a href="/type/${item.termId?if_exists}" class="menu_a">${item.name?if_exists}</a></li> </#if> </#list> </#if> </@customTag>