如何建设网站吸引人,绍兴在线制作网站,深圳市建设集团和恒大的关系,精湛的合肥网站建设Java树形结构集合分页需求难点实现第一步#xff1a;查出所有树形集合数据 #xff08;需进行缓存处理#xff09;selectTree 方法步骤#xff1a;TreeUtil类#xff1a;第二步#xff1a;分页 GoodsCategoryController分页getGoodsCategoryTree方法步骤#xff1a;第三…
Java树形结构集合分页需求难点实现第一步查出所有树形集合数据 需进行缓存处理selectTree 方法步骤TreeUtil类第二步分页 GoodsCategoryController分页getGoodsCategoryTree方法步骤第三步前端实现效果图需求
商品类目树数据量大导致加载太慢需添加一个分页功能。
难点
树状结构不能用mybatis-plus自带的分页功能需自己写分页逻辑因数据量大需进行缓存处理
实现
第一步查出所有树形集合数据 需进行缓存处理
ListGoodsCategoryTree resultList goodsCategoryService.selectTree(null);ListGoodsCategoryTree selectTree(GoodsCategory goodsCategory);selectTree 方法步骤
判断key是否存在如果存在直接取缓存的值 不存在就从数据库查出数据并把值存到redis里。 Overridepublic ListGoodsCategoryTree selectTree(GoodsCategory goodsCategory) {if(redisTemplate.hasKey(CacheConstants.GOODS_CATEGORY_TREE_KEY)){log.info(商品类目管理 selectTree cache);ListGoodsCategoryTree cacheList SpringUtils.getBean(RedisCache.class).getCacheList(CacheConstants.GOODS_CATEGORY_TREE_KEY);return cacheList;}log.info(商品类目管理 selectTree db);ListGoodsCategoryTree treeList getTree(this.list(Wrappers.lambdaQuery(goodsCategory)));if (CollUtil.isNotEmpty(treeList)){SpringUtils.getBean(RedisCache.class).setCacheList(CacheConstants.GOODS_CATEGORY_TREE_KEY,treeList);}return treeList;}其中 getTree()如下 /*** Description: 构建树*/private ListGoodsCategoryTree getTree(ListGoodsCategory entitys) {ListGoodsCategoryTree treeList entitys.stream().filter(entity - !entity.getId().equals(entity.getParentId())).sorted(Comparator.comparingInt(GoodsCategory::getSort)).map(entity - {GoodsCategoryTree node new GoodsCategoryTree();BeanUtil.copyProperties(entity, node);return node;}).collect(Collectors.toList());return TreeUtil.build(treeList, CommonConstants.PARENT_ID);}TreeUtil类
UtilityClass
public class TreeUtil {/*** 两层循环实现建树** param treeNodes 传入的树节点列表* return*/public T extends TreeNode ListT build(ListT treeNodes, Object root) {ListT trees new ArrayList();for (T treeNode : treeNodes) {if (root.equals(treeNode.getParentId())) {trees.add(treeNode);
// trees.sort(Comparator.comparing(TreeNode::getSort));}for (T it : treeNodes) {if (it.getParentId().equals(treeNode.getId())) {treeNode.addChildren(it);
// treeNode.getChildren().sort(Comparator.comparing(TreeNode::getSort));}}}return trees;}
}第二步分页 GoodsCategoryController /*** 返回树形集合分页数据** return*/ApiOperation(value 返回树形集合分页数据)GetMapping(/treePage)public R getGoodsCategoryTree(Page page, GoodsCategory goodsCategory) {//得到所有数据ListGoodsCategoryTree resultList goodsCategoryService.selectTree(null);if (resultList ! null resultList.size() 0) {page.setTotal(resultList.size());}//分页ListGoodsCategoryTree finalList goodsCategoryService.getFinalListByPage(page,resultList);if (finalList ! null finalList.size() 0) {page.setRecords(finalList);}return R.ok(page);}分页 /** 分页查询类目树*/ListGoodsCategoryTree getFinalListByPage(Page page , ListGoodsCategoryTree resultList );getGoodsCategoryTree方法步骤
参考java对list集合进行分页 首先把数据根据创建时间倒序排列再进行分页 Overridepublic ListGoodsCategoryTree getFinalListByPage(Page page, ListGoodsCategoryTree resultList) {//根据创建时间倒序排列ListGoodsCategoryTree treeList resultList.stream().sorted(Comparator.comparing(GoodsCategoryTree::getCreateTime).reversed()).collect(Collectors.toList());//进行分页ListGoodsCategoryTree subList treeList.stream().skip((page.getCurrent()-1)*page.getSize()).limit(page.getSize()).collect(Collectors.toList());return subList;}第三步前端实现
avue-crud 组件加上:page.sync“page” avue-crudrefcrud:datatableData:page.syncpage:permissionpermissionList:table-loadingtableLoading:optiontableOption:before-openbeforeOpenv-modelformon-loadgetPagerefresh-changerefreshChangerow-updatehandleUpdaterow-savehandleSaverow-delhandleDeldata() 加上 page: {total: 0, // 总页数currentPage: 1, // 当前页数pageSize: 20, // 每页显示多少条ascs: [], //升序字段descs: create_time, //降序字段},paramsSearch: {},date: [],};重写getPage()方法
getPage(page, params) {this.tableLoading true;fetchTree(Object.assign({current: page.currentPage,size: page.pageSize,descs: this.page.descs,ascs: this.page.ascs,beginTime: this.date[0],endTime: this.date[1],},params,this.paramsSearch)).then((response) {let tableData response.data.data.records;this.tableData tableData;this.page.total response.data.data.total;this.page.currentPage page.currentPage;this.page.pageSize page.pageSize;let parentIdDIC [{id: 0,name: 顶级分类,parentId: 0,},];tableData.forEach((item) {parentIdDIC.push({id: item.id,name: item.name,parentId: item.parentId,});});this.$refs.crud.DIC.parentId parentIdDIC;this.tableLoading false;}).catch(() {this.tableLoading false;});},效果图
