在淘宝、京东等电商网站，其门户网站都有一个商品品类的多级联动，鼠标移动，就显示，因为前端不是我做的，所以不说明前端实现，只介绍后端实现。

搭建部署SpringBoot环境
配置文件配置：
开启了对Thymeleaf模块引擎的支持

server:   port: 8081 #logging: #  config: classpath:logback_spring.xml #  level: #    com.muses.taoshop: debug #  path: /data/logs  spring:   datasource:      # 主数据源     shop:       url: jdbc:mysql://127.0.0.1:3306/taoshop?autoReconnect=true&useUnicode=true&characterEncoding=utf8&characterSetResults=utf8&useSSL=false       username: root       password: root      driver-class-name: com.mysql.jdbc.Driver     type: com.alibaba.druid.pool.DruidDataSource      # 连接池设置     druid:       initial-size: 5       min-idle: 5       max-active: 20       # 配置获取连接等待超时的时间       max-wait: 60000       # 配置间隔多久才进行一次检测，检测需要关闭的空闲连接，单位是毫秒       time-between-eviction-runs-millis: 60000       # 配置一个连接在池中最小生存的时间，单位是毫秒       min-evictable-idle-time-millis: 300000       # Oracle请使用select 1 from dual       validation-query: SELECT 'x'       test-while-idle: true       test-on-borrow: false       test-on-return: false       # 打开PSCache，并且指定每个连接上PSCache的大小       pool-prepared-statements: true       max-pool-prepared-statement-per-connection-size: 20       # 配置监控统计拦截的filters，去掉后监控界面sql无法统计，'wall'用于防火墙       filters: stat,wall,slf4j       # 通过connectProperties属性来打开mergeSql功能；慢SQL记录       connection-properties: druid.stat.mergeSql=true;druid.stat.slowSqlMillis=5000       # 合并多个DruidDataSource的监控数据       use-global-data-source-stat: true  #  jpa: #    database: mysql #    hibernate: #      show_sql: true #      format_sql: true #      ddl-auto: none #      naming: #        physical-strategy: org.hibernate.boot.entity.naming.PhysicalNamingStrategyStandardImpl  #  mvc: #    view: #      prefix: /WEB-INF/jsp/ #      suffix: .jsp    #添加Thymeleaf配置   thymeleaf:     cache: false     prefix: classpath:/templates/     suffix: .html     mode: HTML5     encoding: UTF-8     content-type: text/html    #Jedis配置 #  jedis : #    pool : #      host : 127.0.0.1 #      port : 6379 #      password : redispassword #      timeout : 0 #      config : #        maxTotal : 100 #        maxIdle : 10 #        maxWaitMillis : 100000 

SpringBoot启动类：

package com.muses.taoshop;    import org.mybatis.spring.boot.autoconfigure.MybatisAutoConfiguration; import org.springframework.boot.*; import org.springframework.boot.autoconfigure.*; import org.springframework.boot.autoconfigure.jdbc.DataSourceAutoConfiguration; import org.springframework.boot.autoconfigure.jdbc.DataSourceTransactionManagerAutoConfiguration; import org.springframework.boot.web.servlet.ServletComponentScan; import org.springframework.cache.annotation.EnableCaching; import org.springframework.scheduling.annotation.EnableAsync; import org.springframework.scheduling.annotation.EnableScheduling; import org.springframework.stereotype.*; import org.springframework.t