<!-- 創(chuàng)建SpringBoot項目加入redis的starter依賴 -->
<dependency>
     <groupId>org.springframework.boot</groupId>
     <artifactId>spring-boot-starter-data-redis</artifactId>
</dependency>

public interface ProductService {
    Map<String,Object> productListPage(int current, int size) throws InterruptedException;
}

/**
 * @author lixiang
 * @date 2023/6/18 21:01
 */
@Service
@Slf4j
public class ProductServiceImpl implements ProductService {
    private static final String PRODUCT_LIST_KEY = "product:list";
    private static final List<Product> PRODUCT_LIST;
    //模擬從數(shù)據(jù)庫中查出來的數(shù)據(jù)
    static {
        PRODUCT_LIST = new ArrayList<>();
        for (int i = 1; i <= 100; i++) {
            Product product = new Product();
            product.setId(UUID.randomUUID().toString().replace("-", ""));
            product.setName("商品名稱:" + i);
            product.setDesc("商品描述:" + i);
            product.setPrice(new BigDecimal(i));
            product.setInventory(2);
            PRODUCT_LIST.add(product);
        }
    }
    @Autowired
    private RedisTemplate redisTemplate;
    @Override
    public Map<String, Object> productListPage(int current, int size) throws InterruptedException {
        //從緩存中拿到分頁數(shù)據(jù)
        List<Product> productList = getProductListByRedis(current, size);
        if (productList == null || productList.size() == 0) {
            log.info("當前緩存中無分頁數(shù)據(jù)，當前頁:" + current + ",頁大小:" + size);
            //從數(shù)據(jù)庫中拿到分頁數(shù)據(jù)
            productList = getProductListByDataSource(current, size);
        }
        Map<String, Object> resultMap = new HashMap<>();
        //計算當前總頁數(shù)
        int totalPage = (PRODUCT_LIST.size() + size - 1) / size;
        resultMap.put("total", PRODUCT_LIST.size());
        resultMap.put("data", productList);
        resultMap.put("pages", totalPage);
        return resultMap;
    }
    private List<Product> getProductListByRedis(int current, int size) {
        log.info("從Redis取出商品信息列表，當前頁:" + current + ",頁大小:" + size);
        // 計算總頁數(shù)
        int pages = pages(size);
        // 起始位置
        int start = current <= 0 ? 0 : (current > pages ? (pages - 1) * size : (current - 1) * size);
        // 終止位置
        int end = start+size-1;
        List<Product> list = redisTemplate.opsForList().range(PRODUCT_LIST_KEY, start, end);
        List<Product> productList = list;
        return productList;
    }
    /**
     * 獲取商品信息集合
     *
     * @return
     */
    private List<Product> getProductListByDataSource(int current, int size) throws InterruptedException {
        //模擬從DB查詢需要300ms
        Thread.sleep(300);
        log.info("從數(shù)據(jù)庫取出商品信息列表，當前頁:" + current + ",頁大小:" + size);
        // 計算總頁數(shù)
        int pages = pages(size);
        // 起始位置
        int start = current <= 0 ? 0 : (current > pages ? (pages - 1) * size : (current - 1) * size);
        //數(shù)據(jù)緩存到redis中
        redisTemplate.opsForList().rightPushAll(PRODUCT_LIST_KEY, PRODUCT_LIST);
        //設置當前key過期時間為1個小時
        redisTemplate.expire(PRODUCT_LIST_KEY,1000*60*60, TimeUnit.MILLISECONDS);
        return PRODUCT_LIST.stream().skip(start).limit(size).collect(Collectors.toList());
    }
    /**
     *  獲取總頁數(shù)
     * @param size
     * @return
     */
    private Integer pages(int size){
        int pages = PRODUCT_LIST.size() % size == 0 ? PRODUCT_LIST.size() / size : PRODUCT_LIST.size() / size + 1;
        return pages;
    }
}

@RestController
@RequestMapping("/api/v1/product")
public class ProductController {
    @Autowired
    private ProductService productService;
    @GetMapping("/page")
    public Map<String,Object> page(@RequestParam("current") int current,@RequestParam("size") int size){
        Map<String, Object> stringObjectMap;
        try {
            stringObjectMap = productService.productListPage(current, size);
        } catch (InterruptedException e) {
            stringObjectMap = new HashMap<>();
        }
        return stringObjectMap;
    }
}

    public Map<String, Object> productListPage(int current, int size) throws InterruptedException {
        //從緩存中拿到分頁數(shù)據(jù)
        List<Product> productList = getProductListByRedis(current, size);
        if (productList == null || productList.size() == 0) {
            log.info("當前緩存中無分頁數(shù)據(jù)，當前頁:" + current + ",頁大小:" + size);
            //從數(shù)據(jù)庫中拿到分頁數(shù)據(jù)
            productList = getProductListByDataSource(current, size);
        }
    }