Java教程
聊聊如何基于spring @Cacheable扩展实现缓存自动过期时间以及即将到期自动刷新
本文主要是介绍聊聊如何基于spring @Cacheable扩展实现缓存自动过期时间以及即将到期自动刷新，对大家解决编程问题具有一定的参考价值，需要的程序猿们随着小编来一起学习吧！
前言
用过spring cache的朋友应该会知道，Spring Cache默认是不支持在@Cacheable上添加过期时间的，虽然可以通过配置缓存容器时统一指定。形如
@Bean
public CacheManager cacheManager(
@SuppressWarnings("rawtypes") RedisTemplate redisTemplate) {
RedisCacheManager cacheManager= new RedisCacheManager(redisTemplate);
cacheManager.setDefaultExpiration(60);
Map<String,Long> expiresMap = new HashMap<>();
expiresMap.put("customUser",30L);
cacheManager.setExpires(expiresMap);
return cacheManager;
}
但有时候我们会更习惯通过注解指定过期时间。今天我们就来聊一下如何扩展@Cacheable实现缓存自动过期以及缓存即将到期自动刷新
实现注解缓存过期前置知识
SpringCache包含两个顶级接口，Cache和CacheManager，通过CacheManager可以去管理一堆Cache。因此我们要扩展@Cacheable，就脱离不了对Cache和CacheManager进行扩展
其次要实现过期时间，首先是引入的缓存产品，他本身就要支持过期时间，比如引入的缓存为ConcurrentHashMap，他原本就是不支持过期时间，如果要扩展，就要非常耗费精力实现
实现注解缓存过期
方法一、通过自定义cacheNames方式
形如下
@Cacheable(cacheNames = "customUser#30", key = "#id")
通过#分隔，#后面部分代表过期时间（单位为秒）
实现逻辑步骤为：
1、自定义缓存管理器并继承RedisCacheManager，同时重写createRedisCache方法
示例：
public class CustomizedRedisCacheManager extends RedisCacheManager {
public CustomizedRedisCacheManager(RedisCacheWriter cacheWriter, RedisCacheConfiguration defaultCacheConfiguration) {
super(cacheWriter, defaultCacheConfiguration);
}
@Override
protected RedisCache createRedisCache(String name, RedisCacheConfiguration cacheConfig) {
String[] array = StringUtils.delimitedListToStringArray(name, "#");
name = array[0];
if (array.length > 1) {
long ttl = Long.parseLong(array[1]);
cacheConfig = cacheConfig.entryTtl(Duration.ofSeconds(ttl));
}
return super.createRedisCache(name, cacheConfig);
}
}
2、将默认的缓存管理器改成我们自定义的缓存管理器
示例：
@EnableCaching
@Configuration
public class CacheConfig {
@Bean
public CacheManager cacheManager() {
RedisCacheConfiguration defaultCacheConfig = RedisCacheConfiguration.defaultCacheConfig()
.entryTtl(Duration.ofDays(1));
CustomizedRedisCacheManager redisCacheManager = new CustomizedRedisCacheManager(RedisCacheWriter.nonLockingRedisCacheWriter(redisConnectionFactory()), defaultCacheConfig);
return redisCacheManager;
}
}
通过如上2个步骤，即可实现缓存过期
方法二：通过自定义派生@Cacheable注解
第一种方法的实现是简单，但缺点是语义不直观，因此得做好宣导以及wiki，不然对于新人来说，他可能都不知道cacheName用#分割是代表啥意思
方法二的实现逻辑步骤如下
1、自定义注解LybGeekCacheable
@Target({ElementType.TYPE, ElementType.METHOD})
@Retention(RetentionPolicy.RUNTIME)
@Inherited
@Documented
@Cacheable(cacheManager = CacheConstant.CUSTOM_CACHE_MANAGER,keyGenerator = CacheConstant.CUSTOM_CACHE_KEY_GENERATOR)
public @interface LybGeekCacheable {
@AliasFor(annotation = Cacheable.class,attribute = "value")
String[] value() default {};
@AliasFor(annotation = Cacheable.class,attribute = "cacheNames")
String[] cacheNames() default {};
@AliasFor(annotation = Cacheable.class,attribute = "key")
String key() default "";
@AliasFor(annotation = Cacheable.class,attribute = "keyGenerator")
String keyGenerator() default "";
@AliasFor(annotation = Cacheable.class,attribute = "cacheResolver")
String cacheResolver() default "";
@AliasFor(annotation = Cacheable.class,attribute = "condition")
String condition() default "";
@AliasFor(annotation = Cacheable.class,attribute = "unless")
String unless() default "";
@AliasFor(annotation = Cacheable.class,attribute = "sync")
boolean sync() default false;
long expiredTimeSecond() default 0;
long preLoadTimeSecond() default 0;
}
大部分注解和@Cacheable保持一致，新增expiredTimeSecond缓存过期时间以及缓存自动刷新时间
preLoadTimeSecond
2、自定义缓存管理器并继承RedisCacheManager并重写loadCaches和createRedisCache
public class CustomizedRedisCacheManager extends RedisCacheManager implements BeanFactoryAware {
private Map<String, RedisCacheConfiguration> initialCacheConfigurations;
private RedisTemplate cacheRedisTemplate;
private RedisCacheWriter cacheWriter;
private DefaultListableBeanFactory beanFactory;
private RedisCacheConfiguration defaultCacheConfiguration;
protected CachedInvocation cachedInvocation;
public CustomizedRedisCacheManager(RedisCacheWriter cacheWriter, RedisCacheConfiguration defaultCacheConfiguration, Map<String, RedisCacheConfiguration> initialCacheConfigurations,RedisTemplate cacheRedisTemplate) {
super(cacheWriter, defaultCacheConfiguration, initialCacheConfigurations);
this.initialCacheConfigurations = initialCacheConfigurations;
this.cacheRedisTemplate = cacheRedisTemplate;
this.cacheWriter = cacheWriter;
this.defaultCacheConfiguration = defaultCacheConfiguration;
//采用spring事件驱动亦可
//EventBusHelper.register(this);
}
public Map<String, RedisCacheConfiguration> getInitialCacheConfigurations() {
return initialCacheConfigurations;
}
@Override
protected Collection<RedisCache> loadCaches() {
List<RedisCache> caches = new LinkedList<>();
for (Map.Entry<String, RedisCacheConfiguration> entry : getInitialCacheConfigurations().entrySet()) {
caches.add(createRedisCache(entry.getKey(), entry.getValue()));
}
return caches;
}
@Override
public RedisCache createRedisCache(String name, @Nullable RedisCacheConfiguration cacheConfig) {
CustomizedRedisCache customizedRedisCache = new CustomizedRedisCache(name, cacheWriter, cacheConfig != null ? cacheConfig : defaultCacheConfiguration);
return customizedRedisCache;
}
}
3、在spring bean初始化完成后,设置缓存过期时间，并重新初始化缓存
Component
@Slf4j
public class CacheExpireTimeInit implements SmartInitializingSingleton, BeanFactoryAware {
private DefaultListableBeanFactory beanFactory;
@Override
public void setBeanFactory(BeanFactory beanFactory) throws BeansException {
this.beanFactory = (DefaultListableBeanFactory)beanFactory;
}
@Override
public void afterSingletonsInstantiated() {
Map<String, Object> beansWithAnnotation = beanFactory.getBeansWithAnnotation(Component.class);
if(MapUtil.isNotEmpty(beansWithAnnotation)){
for (Object cacheValue : beansWithAnnotation.values()) {
ReflectionUtils.doWithMethods(cacheValue.getClass(), method -> {
ReflectionUtils.makeAccessible(method);
boolean cacheAnnotationPresent = method.isAnnotationPresent(LybGeekCacheable.class);
if(cacheAnnotationPresent){
LybGeekCacheable lybGeekCacheable = method.getAnnotation(LybGeekCacheable.class);
CacheHelper.initExpireTime(lybGeekCacheable);
}
});
}
CacheHelper.initializeCaches();
}
}
注： 为啥要重新初始化缓存，主要是为了一开始默认的是没设置缓存过期，重新初始化是为了设置过期时间。为啥调用initializeCaches（）这个方法，看下官方描述就知道了
/**
* Initialize the static configuration of caches.
* <p>Triggered on startup through {@link #afterPropertiesSet()};
* can also be called to re-initialize at runtime.
* @since 4.2.2
* @see #loadCaches()
*/
public void initializeCaches() {
Collection<? extends Cache> caches = loadCaches();
synchronized (this.cacheMap) {
this.cacheNames = Collections.emptySet();
this.cacheMap.clear();
Set<String> cacheNames = new LinkedHashSet<>(caches.size());
for (Cache cache : caches) {
String name = cache.getName();
this.cacheMap.put(name, decorateCache(cache));
cacheNames.add(name);
}
this.cacheNames = Collections.unmodifiableSet(cacheNames);
}
}
他就是在运行的时候，可以重新初始化缓存
4、将默认的缓存管理器改成我们自定义的缓存管理器
@Bean(CacheConstant.CUSTOM_CACHE_MANAGER)
public CacheManager cacheManager(RedisConnectionFactory connectionFactory,RedisTemplate cacheRedisTemplate) {
RedisCacheWriter redisCacheWriter = RedisCacheWriter.nonLockingRedisCacheWriter(connectionFactory);
RedisCacheConfiguration defaultCacheConfig = RedisCacheConfiguration.defaultCacheConfig()
.entryTtl(Duration.ofDays(1));
Map<String, RedisCacheConfiguration> initialCacheConfiguration = new HashMap<>();
return new CustomizedRedisCacheManager(redisCacheWriter,defaultCacheConfig,initialCacheConfiguration,cacheRedisTemplate);
}
5、测试
@LybGeekCacheable(cacheNames = "customUser", key = "#id",expiredTimeSecond = 30)
public User getUserFromRedisByCustomAnno(String id){
System.out.println("get user with id by custom anno: 【" + id + "】");
Faker faker = Faker.instance(Locale.CHINA);
return User.builder().id(id).username(faker.name().username()).build();
}
@Test
public void testCacheExpiredAndPreFreshByCustom() throws Exception{
System.out.println(userService.getUserFromRedisByCustomAnno("1"));
}
以上就是扩展缓存过期的实现主要方式了，接下来我们来聊一下缓存自动刷新
缓存自动刷新
一般来说，当缓存失效时，请求就会打到后端的数据库上，此时可能就会造成缓存击穿现象。因此我们在缓存即将过期时主动刷新缓存，提高缓存的命中率，进而提高性能。
spring4.3的@Cacheable提供了一个sync属性。当缓存失效后，为了避免多个请求打到数据库,系统做了一个并发控制优化，同时只有一个线程会去数据库取数据其它线程会被阻塞
缓存即将到期自动刷新实现步骤
1、封装缓存注解对象CachedInvocation
/**
* @description: 标记了缓存注解的方法类信息,用于主动刷新缓存时调用原始方法加载数据
*/
@Data
@AllArgsConstructor
@NoArgsConstructor
@Builder
public final class CachedInvocation {
private CacheMetaData metaData;
private Object targetBean;
private Method targetMethod;
private Object[] arguments;
public Object invoke()
throws ClassNotFoundException, NoSuchMethodException, InvocationTargetException, IllegalAccessException {
final MethodInvoker invoker = new MethodInvoker();
invoker.setTargetObject(this.getTargetBean());
invoker.setArguments(this.getArguments());
invoker.setTargetMethod(this.getTargetMethod().getName());
invoker.prepare();
return invoker.invoke();
}
}
2、编写一个获取即将到期时间参数切面，并进行事件发布调用对象CachedInvocation
@Component
@Aspect
@Slf4j
@Order(2)
public class LybGeekCacheablePreLoadAspect {
@Autowired
private ApplicationContext applicationContext;
@SneakyThrows
@Around(value = "@annotation(lybGeekCacheable)")
public Object around(ProceedingJoinPoint proceedingJoinPoint,LybGeekCacheable lybGeekCacheable){
buildCachedInvocationAndPushlish(proceedingJoinPoint,lybGeekCacheable);
Object result = proceedingJoinPoint.proceed();
return result;
}
private void buildCachedInvocationAndPushlish(ProceedingJoinPoint proceedingJoinPoint,LybGeekCacheable lybGeekCacheable){
Method method = this.getSpecificmethod(proceedingJoinPoint);
String[] cacheNames = getCacheNames(lybGeekCacheable);
Object targetBean = proceedingJoinPoint.getTarget();
Object[] arguments = proceedingJoinPoint.getArgs();
KeyGenerator keyGenerator = SpringUtil.getBean(CacheConstant.CUSTOM_CACHE_KEY_GENERATOR,KeyGenerator.class);
Object key = keyGenerator.generate(targetBean, method, arguments);
CachedInvocation cachedInvocation = CachedInvocation.builder()
.arguments(arguments)
.targetBean(targetBean)
.targetMethod(method)
.metaData(CacheMetaData.builder()
.cacheNames(cacheNames)
.key(key)
.expiredTimeSecond(lybGeekCacheable.expiredTimeSecond())
.preLoadTimeSecond(lybGeekCacheable.preLoadTimeSecond())
.build()
)
.build();
// EventBusHelper.post(cachedInvocation);
applicationContext.publishEvent(cachedInvocation);
}
3、自定义缓存管理器，接收CachedInvocation
示例
public class CustomizedRedisCacheManager extends RedisCacheManager implements BeanFactoryAware {
//@Subscribe
@EventListener
private void doWithCachedInvocationEvent(CachedInvocation cachedInvocation){
this.cachedInvocation = cachedInvocation;
}
4、自定义cache并重写get方法
@Slf4j
public class CustomizedRedisCache extends RedisCache {
private ReentrantLock lock = new ReentrantLock();
public CustomizedRedisCache(String name, RedisCacheWriter cacheWriter, RedisCacheConfiguration cacheConfig) {
super(name, cacheWriter,cacheConfig);
}
@Override
@Nullable
public ValueWrapper get(Object key) {
ValueWrapper valueWrapper = super.get(key);
CachedInvocation cachedInvocation = CacheHelper.getCacheManager().getCachedInvocation();
long preLoadTimeSecond = cachedInvocation.getMetaData().getPreLoadTimeSecond();
if(ObjectUtil.isNotEmpty(valueWrapper) && preLoadTimeSecond > 0){
String cacheKey = createCacheKey(key);
RedisTemplate cacheRedisTemplate = CacheHelper.getCacheManager().getCacheRedisTemplate();
Long ttl = cacheRedisTemplate.getExpire(cacheKey, TimeUnit.SECONDS);
if(ObjectUtil.isNotEmpty(ttl) && ttl <= preLoadTimeSecond){
log.info(">>>>>>>>>>> cacheKey：{}, ttl: {},preLoadTimeSecond: {}",cacheKey,ttl,preLoadTimeSecond);
ThreadPoolUtils.execute(()->{
lock.lock();
try{
CacheHelper.refreshCache(super.getName());
}catch (Exception e){
log.error("{}",e.getMessage(),e);
}finally {
lock.unlock();
}
});
}
}
return valueWrapper;
}
}
5、缓存即将到期主动刷新缓存方法
public static void refreshCache(String cacheName){
boolean isMatchCacheName = isMatchCacheName(cacheName);
if(isMatchCacheName){
CachedInvocation cachedInvocation = getCacheManager().getCachedInvocation();
boolean invocationSuccess;
Object computed = null;
try {
computed = cachedInvocation.invoke();
invocationSuccess = true;
} catch (Exception ex) {
invocationSuccess = false;
log.error(">>>>>>>>>>>>>>>>> refresh cache fail",ex.getMessage(),ex);
}
if (invocationSuccess) {
Cache cache = getCacheManager().getCache(cacheName);
if(ObjectUtil.isNotEmpty(cache)){
Object cacheKey = cachedInvocation.getMetaData().getKey();
cache.put(cacheKey, computed);
log.info(">>>>>>>>>>>>>>>>>>>> refresh cache with cacheName-->【{}】，key--> 【{}】 finished !",cacheName,cacheKey);
}
}
}
}
6、测试
@LybGeekCacheable(cacheNames = "customUserName", key = "#username",expiredTimeSecond = 20,preLoadTimeSecond = 15)
public User getUserFromRedisByCustomAnnoWithUserName(String username){
System.out.println("get user with username by custom anno: 【" + username + "】");
Faker faker = Faker.instance(Locale.CHINA);
return User.builder().id(faker.idNumber().valid()).username(username).build();
}
@Test
public void testCacheExpiredAndPreFreshByCustomWithUserName() throws Exception{
System.out.println(userService.getUserFromRedisByCustomAnnoWithUserName("zhangsan"));
TimeUnit.SECONDS.sleep(5);
System.out.println("sleep 5 second :" + userService.getUserFromRedisByCustomAnnoWithUserName("zhangsan"));
TimeUnit.SECONDS.sleep(10);
System.out.println("sleep 10 second :" + userService.getUserFromRedisByCustomAnnoWithUserName("zhangsan"));
TimeUnit.SECONDS.sleep(5);
System.out.println("sleep 5 second :" + userService.getUserFromRedisByCustomAnnoWithUserName("zhangsan"));
}
总结
本文主要介绍了如何基于spring @Cacheable扩展实现缓存自动过期时间以及缓存即将到期自动刷新。
不知道有没有朋友会有疑问，为啥@Cacheable不提供一个ttl属性，毕竟也不是很难。在我看来，spring更多提供的是一个通用的规范和标准，如果定义的缓存，本身不支持ttl，你在@Cacheable里面配置ttl就不合适了，有时候实现一个组件或者框架，考虑的是不是能不能实现，而是有没有必要实现，更多是一种权衡和取舍
最后本文的实现的功能， min.jiang 博主他也有实现了一版，博文链接我贴在下方，感兴趣的朋友，可以查看一下
https://www.cnblogs.com/ASPNET2008/p/6511500.html
demo链接
https://github.com/lyb-geek/springboot-learning/tree/master/springboot-cache
这篇关于聊聊如何基于spring @Cacheable扩展实现缓存自动过期时间以及即将到期自动刷新的文章就介绍到这儿，希望我们推荐的文章对大家有所帮助，也希望大家多多支持为之网！
您可能喜欢
-
[开源]10.3K+ Star！轻量强大的开源运维平台，超赞！11-22
-
Flutter基础教程：新手入门指南11-21
-
Flutter跨平台教程：新手入门详解11-21
-
Flutter跨平台教程：新手入门与实践指南11-21
-
Flutter列表组件教程：初学者指南11-21
-
Flutter列表组件教程：新手入门指南11-21
-
Flutter入门教程：初学者必看指南11-21
-
Flutter入门教程：从零开始的Flutter开发指南11-21
-
Flutter升级教程：新手必读的升级指南11-21
-
Flutter升级教程：轻松掌握Flutter版本更新11-21
-
Flutter适配教程：轻松掌握屏幕适配技巧11-21
-
Flutter数据存储教程：入门级详解与实战11-21
-
Flutter数据存储教程：轻松入门数据存储11-21
-
Flutter网络编程教程：新手入门必读11-21
-
Flutter网络编程教程：新手入门指南11-21
栏目导航
