看上图

赋代码：

<dependency>
    <groupId>com.github.ben-manes.caffeine</groupId>
    <artifactId>caffeine</artifactId>
</dependency>

package com.heima.item.config;

import com.github.benmanes.caffeine.cache.Cache;
import com.github.benmanes.caffeine.cache.Caffeine;
import com.heima.item.pojo.Item;
import com.heima.item.pojo.ItemStock;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@Configuration
public class CaffeineConfig {

   @Bean
   public Cache<Long, Item> itemCache(){
      return Caffeine.newBuilder()
            .initialCapacity(100)
            .maximumSize(10_000)
            .build();
   }

   @Bean
   public Cache<Long, ItemStock> stockCache(){
      return Caffeine.newBuilder()
            .initialCapacity(100)
            .maximumSize(10_000)
            .build();
   }
}

@Autowired
private Cache<Long,Item> itemCache;

@Autowired
private Cache<Long,ItemStock> stockCache;

 

    @GetMapping("/{id}")
    public Item findById(@PathVariable("id") Long id){
        return itemCache.get(id,key->itemService.query()
                .ne("status", 3).eq("id", key)
                .one());
    }

    @GetMapping("/stock/{id}")
    public ItemStock findStockById(@PathVariable("id") Long id){
        return stockCache.get(id,key->stockService.getById(key));
    }

 

package com.heima.item.pojo;

import com.baomidou.mybatisplus.annotation.IdType;
import com.baomidou.mybatisplus.annotation.TableField;
import com.baomidou.mybatisplus.annotation.TableId;
import com.baomidou.mybatisplus.annotation.TableName;
import lombok.Data;

import java.util.Date;

@Data
@TableName("tb_item")
public class Item {
    @TableId(type = IdType.AUTO)
    private Long id;//商品id
    private String name;//商品名称
    private String title;//商品标题
    private Long price;//价格（分）
    private String image;//商品图片
    private String category;//分类名称
    private String brand;//品牌名称
    private String spec;//规格
    private Integer status;//商品状态 1-正常，2-下架
    private Date createTime;//创建时间
    private Date updateTime;//更新时间
    @TableField(exist = false)
    private Integer stock;
    @TableField(exist = false)
    private Integer sold;
}

package com.heima.item.pojo;

import com.baomidou.mybatisplus.annotation.IdType;
import com.baomidou.mybatisplus.annotation.TableId;
import com.baomidou.mybatisplus.annotation.TableName;
import lombok.Data;

@Data
@TableName("tb_item_stock")
public class ItemStock {
    @TableId(type = IdType.INPUT, value = "item_id")
    private Long id; //商品id
    private Integer stock; //商品库存
    private Integer sold; //商品销量
}

 Item，ItemStock 是什么无所谓，就是个pojo ，万物皆可存。