Spring Cache 配置及一些问题的解决

配置

1. applicationContext.xml

Spring Cache 配置及一些问题的解决
<beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xmlns:cache="http://www.springframework.org/schema/cache"
   xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsdhttp://www.springframework.org/schema/cache http://www.springframework.org/schema/cache/spring-cache.xsd">
  
    <cache:annotation-driven />
  <!-- 定义缓存管理 -->
    <bean id="cacheManager" class="org.springframework.cache.support.SimpleCacheManager">
        <property name="caches">
            <set>
                <bean class="org.springframework.cache.concurrent.ConcurrentMapCacheFactoryBean"
                      p:name="default"/>
                <bean class="org.springframework.cache.concurrent.ConcurrentMapCacheFactoryBean"
                      p:name="activityCache"/>
                <bean class="org.springframework.cache.concurrent.ConcurrentMapCacheFactoryBean"
                      p:name="awardsCache"/>
            </set>
        </property>
    </bean>
Spring Cache 配置及一些问题的解决

Spring内部默认使用 ConcurrentHashMap 来存储, 配置中的 activityCache awardsCache 就是一个一个的 ConcurrentHashMap 对象的名字. 另外 spring还支持使用 EHCache 来存储缓存.

 

2. 在service的实现类上加上 @Cacheable

Spring Cache 配置及一些问题的解决
//@Service
//public class LotteryActivityServiceImpl implements LotteryActivityService

@Cacheable(value = "activityCache", key = "#shortName")
public LotteryActivity findByShortName(String shortName) {
    log.info("query activity : {} from database.", shortName);
    return activityRepository.findByShortName(shortName);
}
Spring Cache 配置及一些问题的解决

 @Cacheable参数

value   缓存的名称,在 spring 配置文件中定义,必须指定至少一个 例如:@Cacheable(value=”mycache”) 或者 
@Cacheable(value={”cache1”,”cache2”}
key   缓存的 key,可以为空,如果指定要按照 SpEL 表达式编写,如果不指定,则缺省按照方法的所有参数进行组合 例如:
@Cacheable(value=”testcache”,key=”#userName”)
condition 缓存的条件,可以为空,使用 SpEL 编写,返回 true 或者 false,只有为 true 才进行缓存 例如:
@Cacheable(value=”testcache”,condition=”#userName.length()>2”)

在需要清除缓存的方法上加上@CacheEvict 

@CacheEvict(value="activityCache", allEntries = true, beforeInvocation = true)
public void cleanActivityCache(String shortName) {
    log.info("cleaned cache activity : {}", shortName);
}

@CacheEvict 参数

value 缓存的名称,在 spring 配置文件中定义,必须指定至少一个 例如:
@CachEvict(value=”mycache”) 或者 
@CachEvict(value={”cache1”,”cache2”}
key 缓存的 key,可以为空,如果指定要按照 SpEL 表达式编写,如果不指定,则缺省按照方法的所有参数进行组合 例如:
@CachEvict(value=”testcache”,key=”#userName”
condition 缓存的条件,可以为空,使用 SpEL 编写,返回 true 或者 false,只有为 true 才清空缓存 例如:
@CachEvict(value=”testcache”,
condition=”#userName.length()>2”)
allEntries 是否清空所有缓存内容,缺省为 false,如果指定为 true,则方法调用后将立即清空所有缓存 例如:
@CachEvict(value=”testcache”,allEntries=true)
beforeInvocation 是否在方法执行前就清空,缺省为 false,如果指定为 true,则在方法还没有执行的时候就清空缓存,缺省情况下,如果方法执行抛出异常,则不会清空缓存  例如:
@CachEvict(value=”testcache”,beforeInvocation=true)

当需要保证方法被调用,又希望结果被缓存, 可以使用@CachePut 

@CachePut(value="accountCache",key="#account.getName()")// 更新 accountCache 缓存
 public Account updateAccount(Account account) { 
   return updateDB(account); 
 } 

@CachePut 参数

value 缓存的名称,在 spring 配置文件中定义,必须指定至少一个  例如:
@Cacheable(value=”mycache”) 或者 
@Cacheable(value={”cache1”,”cache2”}
key 缓存的 key,可以为空,如果指定要按照 SpEL 表达式编写,如果不指定,则缺省按照方法的所有参数进行组合  例如:
@Cacheable(value=”testcache”,key=”#userName”)
condition 缓存的条件,可以为空,使用 SpEL 编写,返回 true 或者 false,只有为 true 才进行缓存  例如:
@Cacheable(value=”testcache”,condition=”#userName.length()>2”)

 

 注解最好加在实现类而不是接口的方法上

Spring Cache 配置及一些问题的解决
Spring recommends that you only annotate concrete classes (and methods of concrete classes) with the @Cache* annotation, as opposed to annotating interfaces. You certainly can place the @Cache* annotation on an interface (or an interface method), but this works only as you would expect it to if you are using interface-based proxies. The fact that Java annotations are not inherited from interfaces means that if you are using class-based proxies (proxy-target-class="true") or the weaving-based aspect (mode="aspectj"), then the caching settings are not recognized by the proxying and weaving infrastructure, and the object will not be wrapped in a caching proxy, which would be decidedly bad.
Spring Cache 配置及一些问题的解决

带有@Cache* 注解的方法不能被定义在调用该方法的类里, 比如 UserController要调用 findUserByName(String name), 且该方法有 @Cacheabele注解, 那么该方法就不能被定义在 UserController中

In proxy mode (which is the default), only external method calls coming in through the proxy are intercepted. This means that self-invocation, in effect, a method within the target object calling another method of the target object, will not lead to an actual caching at runtime even if the invoked method is marked with @Cacheable - considering using the aspectj mode in this case.

@Cache*注解要加在 public 方法上

When using proxies, you should apply the @Cache* annotations only to methods with public visibility. If you do annotate protected, private or package-visible methods with these annotations, no error is raised, but the annotated method does not exhibit the configured caching settings. Consider the use of AspectJ (see below) if you need to annotate non-public methods as it changes the bytecode itself.

Spring Cache 配置及一些问题的解决

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