目录Spring Cache 缓存拦截器( CacheInterceptor)spring cache常用的三种缓存操作具体整个流程是这样的CacheInterceptor.java定义Cacheable注解定义Rediskey.javaCache.javaRedisCache.javaCacheManager.javaAbstractCacheManager.javaRedisCacheManager.java实现CacheInterceptor.java配置Spring.xml测试使用
Spring Cache 缓存拦截器( CacheInterceptor)
打开Spring Cache的核心缓存拦截器CacheInterceptor，可以看到具体实现：
public class CacheInterceptor extends CacheAspectSupport implements MethodInterceptor, Serializable {@Overridepublic Object invoke(final MethodInvocation invocation) throws Throwable {Method method = invocation.getMethod();CacheOperationInvoker aopAllianceInvoker = new CacheOperationInvoker() {@Overridepublic Object invoke() {try {return invocation.proceed();}catch (Throwable ex) {throw new ThrowableWrapper(ex);}}};try {return execute(aopAllianceInvoker, invocation.getThis(), method, invocation.getArguments());}catch (CacheOperationInvoker.ThrowableWrapper th) {throw th.getOriginal();}}}
CacheInterceptor默认实现了Spring aop的MethodInterceptor接口，MethodInterceptor的功能是做方法拦截。拦截的方法都会调用invoke方法，在invoke方法里面主要缓存逻辑是在execute方法里面，该方法是继承了父类CacheAspectSupport。
protected Object execute(CacheOperationInvoker invoker, Object target, Method method, Object[] args) {// Check whether aspect is enabled (to cope with cases where the AJ is pulled in automatically)if (this.initialized) {Class<?> targetClass = getTargetClass(target);//获取执行方法上所有的缓存操作集合。如果有缓存操作则执行到execute(...)，如果没有就执行invoker.invoke()直接调用执行方法了Collection<CacheOperation> operations = getCacheOperationSource().getCacheOperations(method, targetClass);if (!CollectionUtils.isEmpty(operations)) {return execute(invoker, method, new CacheOperationContexts(operations, method, args, target, targetClass));}}return invoker.invoke();}
集合Collection operations中存放了所有的缓存操作CachePutOperation、CacheableOperation、CacheEvictOperation
spring cache常用的三种缓存操作 @CachePut：执行方法后，将方法返回结果存放到缓存中。不管有没有缓存过，执行方法都会执行，并缓存返回结果（unless可以否决进行缓存）。（当然，这里说的缓存都要满足condition条件） @Cacheable：如果没有缓存过，获取执行方法的返回结果；如果缓存过，则直接从缓存中获取，不再执行方法。 @CacheEvict：如果设置了beforeIntercepte则在方法执行前进行缓存删除操作，如果没有，则在执行方法调用完后进行缓存删除操作。
private Object execute(final CacheOperationInvoker invoker, Method method, CacheOperationContexts contexts) {// Special handling of synchronized invocationif (contexts.isSynchronized()) {CacheOperationContext context = contexts.get(CacheableOperation.class).iterator().next();if (isConditionPassing(context, CacheOperationExpressionEvaluator.NO_RESULT)) {Object key = generateKey(context, CacheOperationExpressionEvaluator.NO_RESULT);Cache cache = context.getCaches().iterator().next();try {return wrapCacheValue(method, cache.get(key, new Callable<Object>() {@Overridepublic Object call() throws Exception {return unwrapReturnValue(invokeOperation(invoker));}}));}catch (Cache.ValueRetrievalException ex) {// The invoker wraps any Throwable in a ThrowableWrapper instance so we// can just make sure that one bubbles up the stack.throw (CacheOperationInvoker.ThrowableWrapper) ex.getCause();}}else {// No caching required, only call the underlying methodreturn invokeOperation(invoker);}}// 处理beforeIntercepte=true的缓存删除操作processCacheEvicts(contexts.get(CacheEvictOperation.class), true,CacheOperationExpressionEvaluator.NO_RESULT);// 从缓存中查找，是否有匹配@Cacheable的缓存数据Cache.ValueWrapper cacheHit = findCachedItem(contexts.get(CacheableOperation.class));// 如果@Cacheable没有被缓存，那么就需要将数据缓存起来，这里将@Cacheable操作收集成CachePutRequest集合，以便后续做@CachePut缓存数据存放。List<CachePutRequest> cachePutRequests = new LinkedList<CachePutRequest>();if (cacheHit == null) {collectPutRequests(contexts.get(CacheableOperation.class),CacheOperationExpressionEvaluator.NO_RESULT, cachePutRequests);}Object cacheValue;Object returnValue;//如果没有@CachePut操作，就使用@Cacheable获取的结果（可能也没有@Cableable，所以result可能为空）。if (cacheHit != null && cachePutRequests.isEmpty() && !hasCachePut(contexts)) {//如果没有@CachePut操作，并且cacheHit不为空，说明命中缓存了，直接返回缓存结果cacheValue = cacheHit.get();returnValue = wrapCacheValue(method, cacheValue);}else {// 否则执行具体方法内容，返回缓存的结果returnValue = invokeOperation(invoker);cacheValue = unwrapReturnValue(returnValue);}// Collect any explicit @CachePutscollectPutRequests(contexts.get(CachePutOperation.class), cacheValue, cachePutRequests);// Process any collected put requests, either from @CachePut or a @Cacheable missfor (CachePutRequest cachePutRequest : cachePutRequests) {cachePutRequest.apply(cacheValue);}// Process any late evictionsprocessCacheEvicts(contexts.get(CacheEvictOperation.class), false, cacheValue);return returnValue;}//根据key从缓存中查找，返回的结果是ValueWrapper，它是返回结果的包装器private Cache.ValueWrapper findCachedItem(Collection<CacheOperationContext> contexts) {Object result = CacheOperationExpressionEvaluator.NO_RESULT;for (CacheOperationContext context : contexts) {if (isConditionPassing(context, result)) {Object key = generateKey(context, result);Cache.ValueWrapper cached = findInCaches(context, key);if (cached != null) {return cached;}else {if (logger.isTraceEnabled()) {logger.trace("No cache entry for key '" + key + "' in cache(s) " + context.getCacheNames());}}}}return null;}private Cache.ValueWrapper findInCaches(CacheOperationContext context, Object key) {for (Cache cache : context.getCaches()) {Cache.ValueWrapper wrapper = doGet(cache, key);if (wrapper != null) {if (logger.isTraceEnabled()) {logger.trace("Cache entry for key '" + key + "' found in cache '" + cache.getName() + "'");}return wrapper;}}return null;}
具体整个流程是这样的
CacheInterceptor.java
项目中基本上都需要使用到Cache的功能, 但是Spring提供的Cacheable并不能很好的满足我们的需求, 所以这里自己借助Spring思想完成自己的业务逻辑.
定义Cacheable注解
@Target({ElementType.METHOD, ElementType.TYPE})@Retention(RetentionPolicy.RUNTIME)@Inherited@Documentedpublic @interface Cacheable { RedisKey value(); String key();}
定义Rediskey.java
public enum RedisKeyEnum { TEST_CACHE("test:", 24, TimeUnit.HOURS, "Test"); /** * 缓存Key的前缀 */ private String keyPrefix; /** * 过期时间 */ private long timeout; /** * 过期时间单位 */ private TimeUnit timeUnit; /** * 描述 */ private String desc; private static final String REDIS_KEY_DEFUALT_SEPARATOR = ":"; RedisKey(String keyPrefix, long timeout, TimeUnit timeUnit, String desc){ this.keyPrefix = keyPrefix; this.timeout = timeout; this.timeUnit = timeUnit; this.desc = desc; } public long getTimeout() { return timeout; } public TimeUnit getTimeUnit() { return timeUnit; } public String getDesc() { return desc; } /** * 获取完整的缓存Key * @param keys * @return */ public String getKey(String... keys) { if(keys == null || keys.length <= 0){ return this.keyPrefix; } String redisKey = keyPrefix; for (int i = 0, length = keys.length; i < length; i++) { String key = keys[i]; redisKey += key; if (i < length - 1) { redisKey += REDIS_KEY_DEFUALT_SEPARATOR; } } return redisKey; }}
Cache.java
public interface Cache<K, V> { /** * 返回缓存名称 * @return */ String getName(); /** * 添加一个缓存实例 * * @param key * @param value */ V put(K key, V value); /** * 添加一个可过期的缓存实例 * @param key * @param value * @param expire * @param timeUnit * @return */ V put(K key, V value, long expire, TimeUnit timeUnit); /** * 返回缓存数据 * * @param key * @return */ V get(K key); /** * 删除一个缓存实例, 并返回缓存数据 * * @param key * @return */ void remove(K key); /** * 获取所有的缓存key * @return */ Set<K> keys(); /** * 获取所有的缓存key * @return */ Set<K> keys(K pattern); /** * 获取所有的缓存数据 * @return */ Collection<V> values(); /** * 清空所有缓存 */ void clear();}
RedisCache.java
public class RedisCache<K, V> implements Cache<K, V> { public static final String DEFAULT_CACHE_NAME = RedisCache.class.getName() + "_CACHE_NAME"; private RedisTemplate<K, V> redisTemplate; private ValueOperations<K, V> valueOperations; public RedisCache(RedisTemplate redisTemplate) { this.redisTemplate = redisTemplate; this.valueOperations = redisTemplate.opsForValue(); DataType dataType = redisTemplate.type("a"); } @Override public String getName() { return DEFAULT_CACHE_NAME; } @Override public V put(K key, V value) { valueOperations.set(key, value); return value; } @Override public V put(K key, V value, long expire, TimeUnit timeUnit) { valueOperations.set(key, value, expire, timeUnit); return value; } @Override public V get(K key) { return valueOperations.get(key); } @Override public void remove(K key) {// V value = valueOperations.get(key); redisTemplate.delete(key); } @Override public Set<K> keys() { return null; } @Override public Set<K> keys(K pattern) { return redisTemplate.keys(pattern); } @Override public Collection<V> values() { return null; } @Override public void clear() { }}
CacheManager.java
public interface CacheManager { /** * 获取缓存 * @return */ Cache getCache(String name); /** * 获取所有的缓存名称 */ Collection<String> getCacheNames(); }
AbstractCacheManager.java
public abstract class AbstractCacheManager implements CacheManager, InitializingBean, DisposableBean { private static final Logger logger = LoggerFactory.getLogger(AbstractCacheManager.class); private final Map<String, Cache> cacheMap = new ConcurrentHashMap<>(16); private volatile Set<String> cacheNames = Collections.emptySet(); private static final String DEFAULT_CACHE_NAME_SUFFIX = "_CACHE_NAME"; @Override public void afterPropertiesSet() throws Exception { initlalizingCache(); } private void initlalizingCache(){ Collection<? extends Cache> caches = loadCaches(); synchronized (this.cacheMap) { this.cacheNames = Collections.emptySet(); this.cacheMap.clear(); Set<String> cacheNames = new LinkedHashSet<String>(caches.size()); for (Cache cache : caches) { String name = cache.getName(); if(StringUtils.isEmpty(name)){ name = cache.getClass().getName() + DEFAULT_CACHE_NAME_SUFFIX; } this.cacheMap.put(name, cache); cacheNames.add(name); } this.cacheNames = Collections.unmodifiableSet(cacheNames); } } @Override public Cache getCache(String name) { Cache cache = cacheMap.get(name); if(cache != null){ return cache; } return null; } protected abstract Collection<? extends Cache> loadCaches(); @Override public Collection<String> getCacheNames() { return this.cacheNames; } @Override public void destroy() throws Exception { cacheMap.clear(); }}
RedisCacheManager.java
public class RedisCacheManager extends AbstractCacheManager { private RedisTemplate redisTemplate; public RedisCacheManager(RedisTemplate redisTemplate) { this.redisTemplate = redisTemplate; } @Override protected Collection<? extends Cache> loadCaches() { Collection<Cache<String, Object>> caches = new ArrayList<>(); RedisCache<String, Object> redisCache = new RedisCache<>(redisTemplate); caches.add(redisCache); return caches; }}
实现CacheInterceptor.java
/** * 缓存数据过滤器, 缓存到redis数据中的数据是ServiceResult.getDateMap()数据 * 使用: 在service方法上添加com.chinaredstar.urms.annotations.Cacheable注解, 并指定RedisKeyEunm和cache key, cache key支持Spel表达式 * 以下情况不缓存数据: * 1: 返回状态为fasle时, 不缓存数据 * 2: 返回dataMap为空时, 不缓存数据 * 3: 返回数据结构不是ServiceReslut实例时, 不缓存数据 * * 当缓存问题时, 不影响正常业务, 但所有的请求都会打到DB上, 对DB有很大的冲击 */public class CacheInterceptor implements MethodInterceptor { private static final Logger logger = LoggerFactory.getLogger(CacheInterceptor.class); private static final ParameterNameDiscoverer parameterNameDiscoverer = new DefaultParameterNameDiscoverer(); private CacheManager cacheManager; public void setCacheManager(CacheManager cacheManager) { this.cacheManager = cacheManager; } @Override public Object invoke(MethodInvocation methodInvocation) throws Throwable { Method method = methodInvocation.getMethod(); Object[] args = methodInvocation.getArguments(); Cacheable cacheable = method.getAnnotation(Cacheable.class); if (cacheable == null) { return methodInvocation.proceed(); } String key = parseCacheKey(method, args, cacheable.key()); logger.info(">>>>>>>> -- 获取缓存key : {}", key); if(StringUtils.isEmpty(key)){ return methodInvocation.proceed(); } RedisKey redisKey = cacheable.value(); Cache cache = cacheManager.getCache(RedisCache.DEFAULT_CACHE_NAME); Object value = null; try{ value = cache.get(redisKey.getKey(key)); } catch (Exception e){ logger.info(">>>>>>>> -- 从缓存中获取数据异常 : {}", ExceptionUtil.exceptionStackTrace(e)); } if (value != null) { logger.info(">>>>>>>> -- 从缓存中获取数据 : {}", JsonUtil.toJson(value)); return ServiceResult.newInstance(true, value); } value = methodInvocation.proceed(); logger.info(">>>>>>>> -- 从接口中获取数据 : {}", JsonUtil.toJson(value)); if ( value != null && value instanceof ServiceResult ) { ServiceResult result = (ServiceResult) value; if(!result.isSuccess() || result.getDataMap() == null){ return value; } try{ cache.put(redisKey.getKey(key), result.getDataMap(), redisKey.getTimeout(), redisKey.getTimeUnit()); } catch (Exception e){ logger.info(">>>>>>>> -- 将数据放入缓存异常 : {}", ExceptionUtil.exceptionStackTrace(e)); } } return value; } /** * 使用SpeL解析缓存key * @param method * @param args * @param expressionString * @return */ private String parseCacheKey(Method method, Object[] args, String expressionString) { String[] parameterNames = parameterNameDiscoverer.getParameterNames(method); EvaluationContext context = new StandardEvaluationContext(); if (parameterNames != null && parameterNames.length > 0 && args != null && args.length > 0 && args.length == parameterNames.length ) { for (int i = 0, length = parameterNames.length; i < length; i++) { context.setVariable(parameterNames[i], args[i]); } } ExpressionParser parser = new SpelExpressionParser(); Expression expression = parser.parseExpression(expressionString); return (String) expression.getValue(context); }}
配置Spring.xml
<bean id="redisCacheManager" class="com.package.cache.RedisCacheManager"> <constructor-arg ref="cacheRedisTemplate" /> </bean> <bean id="cacheInterceptor" class="com.package.interceptor.CacheInterceptor" p:cacheManager-ref="redisCacheManager"/> <!-- 方法拦截器 MethodInterceptor --> <aop:config proxy-target-class="true"> <aop:pointcut id="cacheInterceptorPointcut" expression="execution(* com.package..*(..)) and @annotation(com.package.annotations.Cacheable)"/> <aop:advisor advice-ref="cacheInterceptor" pointcut-ref="cacheInterceptorPointcut" order="2" /> </aop:config>
测试使用
@Cacheable(value = RedisKey.TEST_CACHE, key = "#code + ':' + #user.id")public ServiceResult<String> test(String code, User user){ return new ServiceResult("success");}
说明
Cacheable其中的参数key拼接的规则支持Spring SpeL表达式。其规则和Spring Cacheable使用方法一致。
以上为个人经验，希望能给大家一个参考，也希望大家多多支持。
看着书里九万五千公里的绚丽。又或是和我一样，
