代碼https://github.com/HiwayChe/zheng/tree/develop/zheng-test

spring cache篇http://www.lxweimin.com/p/b9e85a139ea0

Cache切面在事務切面前面，只有事務執行成功才往cache中緩存數據。
代碼中共有4個切面，分別為獲取緩存失效時間，設置緩存，切換數據源，事務。
執行順序：CacheExpireAdvice.before->CacheInterceptor.invoke->MultiDataSourceAdvice.before->TransactionInterceptor.invode->MultiDataSourceAdvice.afterReturning->CacheExpireAdvice.afterReturning。
其中CacheInterceptor和TransactionInterceptor沒有before,afterReturning之分。
afterReturning只有在方法成功后才執行，如果target中拋了異常，那么afterReturning是不會執行的。如TransactionInterceptor執行失敗，CacheInterceptor是不會緩存數據的。

執行CacheTest4測試用例，日志解析如下：

@Test
    public void test(){
        String key = "fafaxxx";
        Account account;
        for(int i=0;i<2;i++){
            account = this.accountService.getAccountByName(key);
            try {
                this.logger.info("sleeping................");
                TimeUnit.SECONDS.sleep(3);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }

        this.accountService.update(key);
        this.logger.info("cache evicted....");
        for(int i=0;i<2;i++){
            account = this.accountService.getAccountByName(key);
            try {
                this.logger.info("sleeping................");
                TimeUnit.SECONDS.sleep(3);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }

    }

日志：

#執行CacheExpireAdvice.before方法，獲取緩存失效時間
01-11 00:35:27 [main] INFO  CacheExpireAdvice.before() | CacheExpireAdvice before, target method:getAccountByName
#切換數據源
01-11 00:35:27 [main] INFO  DataSourceAdvice.before() | DataSourceAdvice before,target method:getAccountByName
#當前數據源是read
01-11 00:35:27 [main] INFO  MultiDataSource.determineCurrentLookupKey() | current database:read
#由于是第一次執行，緩存中沒有數據，這里從db中查找
01-11 00:35:27 [main] INFO  AccountService.getFromDB() | =====================real querying db... fafaxxx
#清空數據源設置（到這里說明事務成功了）
01-11 00:35:27 [main] INFO  DataSourceAdvice.afterReturning() | DataSourceAdvice after,target method:getAccountByName
#db中查詢的結果緩存起來，有失效時間的
01-11 00:35:27 [main] INFO  MyRedisCache.put() | cache with expire.....
#清空失效時間值
01-11 00:35:27 [main] INFO  CacheExpireAdvice.afterReturning() | CacheExpireAdvice after, target method:getAccountByName
#代碼sleeping
01-11 00:35:27 [main] INFO  CacheTest4.test() | sleeping................
#第二次執行（這時緩存中有數據了），獲取緩存失效值
01-11 00:35:30 [main] INFO  CacheExpireAdvice.before() | CacheExpireAdvice before, target method:getAccountByName
#由于緩存中有數據了，這里直接在CacheInterceptor中返回，不再走db。清空失效值
01-11 00:35:30 [main] INFO  CacheExpireAdvice.afterReturning() | CacheExpireAdvice after, target method:getAccountByName
#代碼sleeping
01-11 00:35:30 [main] INFO  CacheTest4.test() | sleeping................
#進入到update方法（這個方法會清空緩存）。
01-11 00:35:33 [main] INFO  DataSourceAdvice.before() | DataSourceAdvice before,target method:update
#切換數據源到write
01-11 00:35:33 [main] INFO  MultiDataSource.determineCurrentLookupKey() | current database:write
01-11 00:35:33 [main] INFO  AccountService.update() | update or delete account from DB, evict from cache
#清空數據源設置
01-11 00:35:33 [main] INFO  DataSourceAdvice.afterReturning() | DataSourceAdvice after,target method:update
01-11 00:35:33 [main] INFO  CacheTest4.test() | cache evicted....
#再次讀取數據，和最上面的一樣了
01-11 00:35:33 [main] INFO  CacheExpireAdvice.before() | CacheExpireAdvice before, target method:getAccountByName
01-11 00:35:33 [main] INFO  DataSourceAdvice.before() | DataSourceAdvice before,target method:getAccountByName
01-11 00:35:33 [main] INFO  MultiDataSource.determineCurrentLookupKey() | current database:read
01-11 00:35:33 [main] INFO  AccountService.getFromDB() | =====================real querying db... fafaxxx
01-11 00:35:33 [main] INFO  DataSourceAdvice.afterReturning() | DataSourceAdvice after,target method:getAccountByName
01-11 00:35:33 [main] INFO  MyRedisCache.put() | cache with expire.....
01-11 00:35:33 [main] INFO  CacheExpireAdvice.afterReturning() | CacheExpireAdvice after, target method:getAccountByName
01-11 00:35:33 [main] INFO  CacheTest4.test() | sleeping................
01-11 00:35:36 [main] INFO  CacheExpireAdvice.before() | CacheExpireAdvice before, target method:getAccountByName
01-11 00:35:36 [main] INFO  CacheExpireAdvice.afterReturning() | CacheExpireAdvice after, target method:getAccountByName
01-11 00:35:36 [main] INFO  CacheTest4.test() | sleeping................