Spring優雅整合Redis緩存

時間 2020-04-13

標籤 spring 優雅整合 redis 緩存欄目 Spring 简体版

原文原文鏈接

「小明，多系統的session共享，怎麼處理？」「Redis緩存啊！」「小明，我想實現一個簡單的消息隊列？」「Redis緩存啊！」前端

「小明，分佈式鎖這玩意有什麼方案？」「Redis緩存啊！」「小明，公司系統響應如蝸牛，咋整？」「Redis緩存啊！」vue

本着研究的精神，咱們來分析下小明的第四個問題。java

準備：
Idea2019.03/Gradle6.0.1/Maven3.6.3/JDK11.0.4/Lombok0.28/SpringBoot2.2.4RELEASE/mybatisPlus3.3.0/Soul2.1.2/git

Dubbo2.7.5/Druid1.2.21/Zookeeper3.5.5/Mysql8.0.11/Vue2.5/Redis3.2github

難度：新手-- 戰士 --老兵--大師redis

目標：
Spring優雅整合Redis作數據庫緩存
步驟：
爲了碰見各類問題，同時保持時效性，我儘可能使用最新的軟件版本。源碼地址： https://github.com/xiexiaobiao/vehicle-shop-admin
1 先說結論
Redis緩存不是金彈，若系統DB毫無壓力，系統性能瓶頸不在DB上，不建議強加緩存層！spring

增長業務複雜度：同一緩存必須被所有相關方法所覆蓋，如訂單緩存，只要涉及到訂單數據更新的方法都要進行緩存邏輯處理。
同時，KV存儲時，因各方法返回的類型不一樣，這樣就須要多個緩存池，但各方法後臺的數據又存在關聯，每每致使一個方法需sql

要處理關聯的多個緩存，從而造成網狀處理邏輯。數據庫

存在併發問題：緩存沒有鎖機制，B線程進行DB更新，同時A線程請求數據，緩存中存在即返回，但B線程還未更新到緩存，導

致緩存與DB不一致；或者A線程B線程都進行DB更新，但寫入緩存的順序發生顛倒，也會致使緩存與DB不一致，請看官君想一想如何解決；json

3.內存消耗：小數據量可直接所有進內存，但海量數據不可能所有直接進入Redis，機器吃不消！可考慮只緩存DB數據索引，而後配合

「布隆過濾器」攔截無效請求，有效請求再去DB查詢；

緩存位置：緩存註解的方法，執行時序上應儘可能靠近DB，遠離前端，如放dao層，請看官君思考下爲啥。

適用場景：1.確認DB爲系統性能瓶頸，2.數據內容穩定，低頻更新，高頻查詢，如歷史訂單數據；3.熱點數據，如新上市商品；

2 步驟
2.1 原理
這裏我說的是註解模式，有四個註解，SpringCache緩存原理即註解+攔截器 org.springframework.cache.interceptor.CacheInterceptor 對方法進行攔截處理：

@Cacheable：可標記在類或方法上。標記在類上則緩存該類全部方法的返回值。請求方法時，先在緩存進行key匹配，存在則直接取緩存數據並返回。主要參數表：

@CacheEvict：從緩存中移除相應數據。主要參數表：

@CachePut：方法支持緩存功能。與@Cacheable不一樣的是使用@CachePut標註的方法在執行前不會去檢查緩存中是否存在以前執行過的結果，

而是每次都會執行該方法，並將執行結果以鍵值對的形式存入指定的緩存中。主要參數表：

@Caching: 多個Cache註解組合使用,好比新增用戶時，同時要刪除其餘緩存，並更新用戶信息緩存，即以上三個註解的集合。

2.2 編碼
項目有五個微服務，我僅改造了customer服務模塊：

引入依賴，build.gradle文件：

Redis配置項，resources/config/application-dev.yml文件：

文件： com.biao.shop.customer.conf.RedisConf

@Configurationbr/>@EnableCaching
public class RedisConf {

@Bean
public RedisCacheManager cacheManager(RedisConnectionFactory redisConnectionFactory){
    return RedisCacheManager.create(redisConnectionFactory);
}

@Bean
public CacheManager cacheManager() {
    // configure and return an implementation of Spring's CacheManager SPI
     SimpleCacheManager cacheManager = new SimpleCacheManager();
     cacheManager.setCaches(Arrays.asList(new ConcurrentMapCache("default")));
     return cacheManager;
}

@Bean
public RedisTemplate<String,Object> redisTemplate(RedisConnectionFactory factory){
    RedisTemplate<String,Object> redisTemplate = new RedisTemplate<>();
    redisTemplate.setConnectionFactory(factory);
    // 設置key的序列化器
    redisTemplate.setKeySerializer(new StringRedisSerializer());
    // 設置value的序列化器,使用Jackson 2，將對象序列化爲JSON
    Jackson2JsonRedisSerializer jackson2JsonRedisSerializer =
            new Jackson2JsonRedisSerializer(Object.class);
    // json轉對象類，不設置,默認的會將json轉成hashmap
    ObjectMapper mapper = new ObjectMapper();
    mapper.setVisibility(PropertyAccessor.ALL, JsonAutoDetect.Visibility.ANY);
    mapper.enableDefaultTyping(ObjectMapper.DefaultTyping.NON_FINAL);
    jackson2JsonRedisSerializer.setObjectMapper(mapper);
    return redisTemplate;
}

}
以上代碼解析：1.聲明緩存管理器CacheManager，會建立一個切面（aspect）並觸發Spring緩存註解的切點，根據類或者方法所使用的註解以及緩存的狀態，
這個切面會從緩存中獲取數據，將數據添加到緩存之中或者從緩存中移除某個值 2. RedisTemplate即爲Redis鏈接器，實際上即爲jedis客戶端。

文件： com.biao.shop.customer.impl.ShopClientServiceImpl

@org.springframework.stereotype.Servicebr/>@Slf4j
public class ShopClientServiceImpl extends ServiceImpl<ShopClientDao, ShopClientEntity> implements ShopClientService {

private final Logger logger = LoggerFactory.getLogger(ShopClientServiceImpl.class);

private ShopClientDao shopClientDao;

@Autowired
public ShopClientServiceImpl(ShopClientDao shopClientDao){
    this.shopClientDao = shopClientDao;
}

@Override
public String getMaxClientUuId() {
    return shopClientDao.selectList(new LambdaQueryWrapper<ShopClientEntity>()
            .isNotNull(ShopClientEntity::getClientUuid).orderByDesc(ShopClientEntity::getClientUuid))
            .stream().limit(1).collect(Collectors.toList())
            .get(0).getClientUuid();
}

@Override
@Caching(put = @CachePut(cacheNames = {"shopClient"},key = "#root.args[0].clientUuid"),
        evict = @CacheEvict(cacheNames = {"shopClientPage","shopClientPlateList","shopClientList"},allEntries = true))
public int createClient(ShopClientEntity clientEntity) {
    clientEntity.setGenerateDate(LocalDateTime.now());
    return shopClientDao.insert(clientEntity);
}

/** */
@Override
@CacheEvict(cacheNames = {"shopClient","shopClientPage","shopClientPlateList","shopClientList"},allEntries = true)
public int deleteBatchById(Collection<Integer> ids) {
    logger.info("deleteBatchById 刪除Redis緩存");
    return shopClientDao.deleteBatchIds(ids);
}

@Override
@CacheEvict(cacheNames = {"shopClient","shopClientPage","shopClientPlateList","shopClientList"},allEntries = true)
public int deleteById(int id) {
    logger.info("deleteById 刪除Redis緩存");
    return shopClientDao.deleteById(id);
}

@Override
@Caching(evict = {@CacheEvict(cacheNames = "shopClient",key = "#root.args[0]"),
        @CacheEvict(cacheNames = {"shopClientPage","shopClientPlateList","shopClientList"},allEntries = true)})
public int deleteByUUid(String uuid) {
    logger.info("deleteByUUid 刪除Redis緩存");
    QueryWrapper<ShopClientEntity> qw = new QueryWrapper<>();
    qw.eq(true,"uuid",uuid);
    return shopClientDao.delete(qw);
}

@Override
@Caching(put = @CachePut(cacheNames = "shopClient",key = "#root.args[0].clientUuid"),
        evict = @CacheEvict(cacheNames = {"shopClientPage","shopClientPlateList","shopClientList"},allEntries = true))
public int updateClient(ShopClientEntity clientEntity) {
    logger.info("updateClient 更新Redis緩存");
    clientEntity.setModifyDate(LocalDateTime.now());
    return shopClientDao.updateById(clientEntity);
}

@Override
@CacheEvict(cacheNames = {"shopClient","shopClientPage","shopClientPlateList","shopClientList"},allEntries = true)
public int addPoint(String uuid,int pointToAdd) {
    ShopClientEntity clientEntity =  this.queryByUuId(uuid);
    log.debug(clientEntity.toString());
    clientEntity.setPoint(Objects.isNull(clientEntity.getPoint()) ? 0 : clientEntity.getPoint() + pointToAdd);
    return shopClientDao.updateById(clientEntity);
}

@Override
@Cacheable(cacheNames = "shopClient",key = "#root.args[0]")
public ShopClientEntity queryByUuId(String uuid) {
    logger.info("queryByUuId 未使用Redis緩存");
    QueryWrapper<ShopClientEntity> qw = new QueryWrapper<>();
    qw.eq(true,"client_uuid",uuid);
    return shopClientDao.selectOne(qw);
}

@Override
@Cacheable(cacheNames = "shopClientById",key = "#root.args[0]")
public ShopClientEntity queryById(int id) {
    logger.info("queryById 未使用Redis緩存");
    return shopClientDao.selectById(id);
}

@Override
@Cacheable(cacheNames = "shopClientPage")
public PageInfo<ShopClientEntity> listClient(Integer current, Integer size, String clientUuid, String name,
                                             String vehiclePlate, String phone) {
    logger.info("listClient 未使用Redis緩存");
    QueryWrapper<ShopClientEntity> qw = new QueryWrapper<>();
    Map<String,Object> map = new HashMap<>(4);
    map.put("client_uuid",clientUuid);
    map.put("vehicle_plate",vehiclePlate);
    map.put("phone",phone);
    // "name" 模糊匹配
    boolean valid = Objects.isNull(name);
    qw.allEq(true,map,false).like(!valid,"client_name",name);
    PageHelper.startPage(current,size);
    List<ShopClientEntity> clientEntities = shopClientDao.selectList(qw);
    return  PageInfo.of(clientEntities);
}

// java Stream
@Override
@Cacheable(cacheNames = "shopClientPlateList")
public List<String> listPlate() {
    logger.info("listPlate 未使用Redis緩存");
    List<ShopClientEntity> clientEntities =
            shopClientDao.selectList(new LambdaQueryWrapper<ShopClientEntity>().isNotNull(ShopClientEntity::getVehiclePlate));
    return clientEntities.stream().map(ShopClientEntity::getVehiclePlate).collect(Collectors.toList());
}

@Override
@Cacheable(cacheNames = "shopClientList",key = "#root.args[0].toString()")
public List<ShopClientEntity> listByClientDto(ClientQueryDTO clientQueryDTO) {
    logger.info("listByClientDto 未使用Redis緩存");
    QueryWrapper<ShopClientEntity> qw = new QueryWrapper<>();
    boolean phoneFlag = Objects.isNull(clientQueryDTO.getPhone());
    boolean clientNameFlag = Objects.isNull(clientQueryDTO.getClientName());
    boolean vehicleSeriesFlag = Objects.isNull(clientQueryDTO.getVehicleSeries());
    boolean vehiclePlateFlag = Objects.isNull(clientQueryDTO.getVehiclePlate());
    //若有null的條件直接不參與查詢
    qw.eq(!phoneFlag,"phone",clientQueryDTO.getPhone())
            .like(!clientNameFlag,"client_name",clientQueryDTO.getClientName())
            .like(!vehicleSeriesFlag,"vehicle_plate",clientQueryDTO.getVehiclePlate())
            .like(!vehiclePlateFlag,"vehicle_series",clientQueryDTO.getVehicleSeries());
    return shopClientDao.selectList(qw);
}

}
以上代碼解析：