詳解如何使用SpringBoot的緩存@Cacheable

更新時間：2023年06月27日 11:28:40 作者：小石讀史

這篇文章主要為大家介紹了如何使用SpringBoot的緩存@Cacheable詳解，有需要的朋友可以借鑒參考下，希望能夠有所幫助，祝大家多多進步，早日升職加薪

緩存介紹

Spring 從 3.1 開始就引入了對 Cache 的支持。定義了 org.springframework.cache.Cache 和 org.springframework.cache.CacheManager 接口來統(tǒng)一不同的緩存技術。并支持使用 JCache（JSR-107）注解簡化我們的開發(fā)。

其使用方法和原理都類似于 Spring 對事務管理的支持。Spring Cache 是作用在方法上的，其核心思想是，當我們在調用一個緩存方法時會把該方法參數(shù)和返回結果作為一個鍵值對存在緩存中。

Cache 和 CacheManager 接口說明

Cache 接口包含緩存的各種操作集合，你操作緩存就是通過這個接口來操作的。

Cache 接口下 Spring 提供了各種 xxxCache 的實現(xiàn)，比如：RedisCache、EhCache、ConcurrentMapCache

CacheManager 定義了創(chuàng)建、配置、獲取、管理和控制多個唯一命名的 Cache。這些 Cache 存在于 CacheManager 的上下文中。

小結：

每次調用需要緩存功能的方法時，Spring 會檢查指定參數(shù)的指定目標方法是否已經被調用過，如果有就直接從緩存中獲取方法調用后的結果，如果沒有就調用方法并緩存結果后返回給用戶。下次調用直接從緩存中獲取。

二、@Cacheable 注解使用詳細介紹

@Cacheable 這個注解，用它就是為了使用緩存的。所以我們可以先說一下緩存的使用步驟：

緩存使用步驟

1、開啟基于注解的緩存，使用 @EnableCaching 標識在 SpringBoot 的主啟動類上。

2、標注緩存注解即可

① 第一步：開啟基于注解的緩存，使用 @EnableCaching 標注在 springboot 主啟動類上

@EnableSwagger2
@EnableScheduling
@EnableFeignClients(basePackages = {"src.main.biz.smallProject.client","com.codingapi.tx"})
@EnableJpaRepositories(basePackages = {"src.main.biz.smallProject.web.*.dao","src.main.newgrand.framework.common.dao" })
@EntityScan(basePackages = { "src.main.biz.smallProject.web.*.entity","src.main.newgrand.framework.common.domain"})
@EnableCaching
public class StartApp {
    public static void main(String[] args) {
        ApplicationContext context = SpringApplication.run(StartApp.class);
        new SpringUtil().setApplicationContext(context);
    }
}

② 第二步：標注緩存注解

package src.main.biz.smallProject.web.cost.service.impl;
import com.querydsl.core.BooleanBuilder;
import com.querydsl.core.QueryResults;
import com.querydsl.core.types.Projections;
import com.querydsl.jpa.impl.JPAQueryFactory;
import org.apache.commons.lang3.StringUtils;
import org.springframework.beans.BeanUtils;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.cache.annotation.CacheEvict;
import org.springframework.cache.annotation.Cacheable;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;
import src.main.biz.smallProject.utils.CollectionUtils;
import src.main.biz.smallProject.web.construct.form.IdsForm;
import src.main.biz.smallProject.web.cost.dao.BusinessScopeJPA;
import src.main.biz.smallProject.web.cost.entity.BusinessScopeEntity;
import src.main.biz.smallProject.web.cost.entity.QBusinessScopeEntity;
import src.main.biz.smallProject.web.cost.form.BusinessScopeForm;
import src.main.biz.smallProject.web.cost.form.BusinessScopeQueryForm;
import src.main.biz.smallProject.web.cost.service.BusinessScopeService;
import src.main.biz.smallProject.web.cost.vo.BusinessScopeVO;
import src.main.newgrand.framework.common.constants.PageData;
import src.main.newgrand.framework.common.exception.BusinessException;
import src.main.newgrand.framework.common.service.impl.BaseServiceImpl;
import src.main.newgrand.framework.common.utils.ResultRes;
import java.time.LocalDateTime;
import java.util.List;
import static src.main.biz.smallProject.redis.CacheConstants.BUSINESS_SCOPE_CACHE;
/**
 * @Description
 * @Author    yql
 * @Date 2022-05-10 10:44:29 */
@Service
public class BusinessScopeServiceImpl extends BaseServiceImpl<BusinessScopeJPA, BusinessScopeEntity, BusinessScopeVO> implements BusinessScopeService {
    @Autowired
    private JPAQueryFactory jpaQueryFactory;
    QBusinessScopeEntity qBusinessScopeEntity = QBusinessScopeEntity.businessScopeEntity;
    @Autowired
    private BusinessScopeService businessScopeService;
    @Override
    @Transactional(rollbackFor = BusinessException.class)
    @CacheEvict(cacheNames = {BUSINESS_SCOPE_CACHE}, allEntries = true)
    public ResultRes add(BusinessScopeForm form) {
        BusinessScopeEntity businessScopeEntity = new BusinessScopeEntity();
        BeanUtils.copyProperties(form,businessScopeEntity);
        businessScopeService.save(businessScopeEntity);
        return ResultRes.success();
    }
    @Override
    @Transactional(rollbackFor = BusinessException.class)
    @CacheEvict(cacheNames = {BUSINESS_SCOPE_CACHE}, allEntries = true)
    public ResultRes update(BusinessScopeForm form) {
        BusinessScopeEntity businessScopeEntity = findById(form.getPhid());
        if(businessScopeEntity == null){
            throw new BusinessException("數(shù)據不存在，請檢查!");
        }
        BeanUtils.copyProperties(form,businessScopeEntity);
        businessScopeService.updateSelectiveById(businessScopeEntity);
        return ResultRes.success();
    }
    @Override
    @Cacheable(cacheNames = BUSINESS_SCOPE_CACHE, key = "{ " + "#root.methodName, #form.status}", unless = "#result == null")
    public ResultRes<PageData> list(BusinessScopeQueryForm form) {
        long currPage = form.getCurrent();
        long size = form.getSize();
        BooleanBuilder booleanBuilder = new BooleanBuilder();
        booleanBuilder.and(qBusinessScopeEntity.phDelflag.eq(0L));
        if(form.getStatus() != null){
            booleanBuilder.and(qBusinessScopeEntity.status.eq(form.getStatus()));
        }
        QueryResults<BusinessScopeVO> results = jpaQueryFactory
                .select(Projections.bean(
                        BusinessScopeVO.class,
                        qBusinessScopeEntity.phid,
                        qBusinessScopeEntity.name,
                        qBusinessScopeEntity.status))
                .from(qBusinessScopeEntity)
                .where(booleanBuilder)
                .orderBy(qBusinessScopeEntity.phInsertDt.desc())
                .offset((currPage - 1) * size)
                .limit(size).fetchResults();
        PageData pageData = new PageData(results.getResults(), results.getTotal(), size, currPage);
        return ResultRes.success(pageData);
    }
    @Override
    @Transactional(rollbackFor = BusinessException.class)
    @CacheEvict(cacheNames = {BUSINESS_SCOPE_CACHE}, allEntries = true)
    public ResultRes deleteData(IdsForm form) {
        List<Long> ids = form.getIds();
        List<BusinessScopeEntity> businessScopeEntityList = queryFactory.selectFrom(qBusinessScopeEntity)
                .where(qBusinessScopeEntity.phid.in(ids).and(qBusinessScopeEntity.phDelflag.eq(0L)))
                .fetch();
        if(CollectionUtils.isEmpty(businessScopeEntityList)){
            throw new BusinessException("數(shù)據不存在，請檢查!");
        }
        queryFactory.update(qBusinessScopeEntity)
                .set(qBusinessScopeEntity.phDelflag, 1L)
                .set(qBusinessScopeEntity.phUpdateDt, LocalDateTime.now())
                .where(qBusinessScopeEntity.phid.in(ids))
                .execute();
        return ResultRes.success();
    }
}