org.hswebframework.web.cache.spring.fix.FixUseSupperClassFallbackCacheOperationSource.java Source code

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/*
 * Copyright 2002-2017 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.hswebframework.web.cache.spring.fix;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.cache.interceptor.CacheOperation;
import org.springframework.cache.interceptor.CacheOperationSource;
import org.springframework.core.BridgeMethodResolver;
import org.springframework.core.MethodClassKey;
import org.springframework.util.ClassUtils;

import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.util.Collection;
import java.util.Collections;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;

/**
 * Abstract implementation of {@link CacheOperation} that caches attributes
 * for methods and implements a fallback policy: 1. specific target method;
 * 2. target class; 3. declaring method; 4. declaring class/interface.
 * <p>
 * <p>Defaults to using the target class's caching attribute if none is
 * associated with the target method. Any caching attribute associated with
 * the target method completely overrides a class caching attribute.
 * If none found on the target class, the interface that the invoked method
 * has been called through (in case of a JDK proxy) will be checked.
 * <p>
 * <p>This implementation caches attributes by method after they are first
 * used. If it is ever desirable to allow dynamic changing of cacheable
 * attributes (which is very unlikely), caching could be made configurable.
 *
 * @author Costin Leau
 * @author Juergen Hoeller
 * @author zhouhao
 * @see org.springframework.cache.interceptor.AbstractFallbackCacheOperationSource
 * @since 3.1
 */
public abstract class FixUseSupperClassFallbackCacheOperationSource implements CacheOperationSource {

    /**
     * Canonical value held in cache to indicate no caching attribute was
     * found for this method and we don't need to look again.
     */
    private final static Collection<CacheOperation> NULL_CACHING_ATTRIBUTE = new java.util.ArrayList<>();

    /**
     * Logger available to subclasses.
     * <p>As this base class is not marked Serializable, the logger will be recreated
     * after serialization - provided that the concrete subclass is Serializable.
     */
    protected final Log logger = LogFactory.getLog(getClass());

    /**
     * Cache of CacheOperations, keyed by method on a specific target class.
     * <p>As this base class is not marked Serializable, the cache will be recreated
     * after serialization - provided that the concrete subclass is Serializable.
     */
    private final Map<Object, Collection<CacheOperation>> attributeCache = new ConcurrentHashMap<Object, Collection<CacheOperation>>(
            1024);

    /**
     * Determine the caching attribute for this method invocation.
     * <p>Defaults to the class's caching attribute if no method attribute is found.
     *
     * @param method      the method for the current invocation (never {@code null})
     * @param targetClass the target class for this invocation (may be {@code null})
     * @return {@link CacheOperation} for this method, or {@code null} if the method
     * is not cacheable
     */
    @Override
    public Collection<CacheOperation> getCacheOperations(Method method, Class<?> targetClass) {
        if (method.getDeclaringClass() == Object.class) {
            return null;
        }

        Object cacheKey = getCacheKey(method, targetClass);
        Collection<CacheOperation> cached = this.attributeCache.get(cacheKey);

        if (cached != null) {
            return (cached != NULL_CACHING_ATTRIBUTE ? cached : null);
        } else {
            Collection<CacheOperation> cacheOps = computeCacheOperations(method, targetClass);
            if (cacheOps != null) {
                if (logger.isDebugEnabled()) {
                    logger.debug("Adding cacheable method '" + method.getName() + "' with attribute: " + cacheOps);
                }
                this.attributeCache.put(cacheKey, cacheOps);
            } else {
                this.attributeCache.put(cacheKey, NULL_CACHING_ATTRIBUTE);
            }
            return cacheOps;
        }
    }

    /**
     * Determine a cache key for the given method and target class.
     * <p>Must not produce same key for overloaded methods.
     * Must produce same key for different instances of the same method.
     *
     * @param method      the method (never {@code null})
     * @param targetClass the target class (may be {@code null})
     * @return the cache key (never {@code null})
     */
    protected Object getCacheKey(Method method, Class<?> targetClass) {
        return new MethodClassKey(method, targetClass);
    }

    private Collection<CacheOperation> computeCacheOperations(Method method, Class<?> targetClass) {
        // Don't allow no-public methods as required.
        if (allowPublicMethodsOnly() && !Modifier.isPublic(method.getModifiers())) {
            return null;
        }

        // The method may be on an interface, but we need attributes from the target class.
        // If the target class is null, the method will be unchanged.
        Method specificMethod = ClassUtils.getMostSpecificMethod(method, targetClass);
        // If we are dealing with method with generic parameters, find the original method.
        specificMethod = BridgeMethodResolver.findBridgedMethod(specificMethod);

        // First try is the method in the target class.
        // @CacheConfig?
        Collection<CacheOperation> opDef = findCacheOperations(targetClass, specificMethod);
        if (opDef != null) {
            return opDef;
        }

        // Second try is the caching operation on the target class.
        opDef = findCacheOperations(specificMethod.getDeclaringClass());
        if (opDef != null && ClassUtils.isUserLevelMethod(method)) {
            return opDef;
        }

        if (specificMethod != method) {
            // Fallback is to look at the original method.
            opDef = findCacheOperations(targetClass, method);
            if (opDef != null) {
                return opDef;
            }
            // Last fallback is the class of the original method.
            opDef = findCacheOperations(method.getDeclaringClass());
            if (opDef != null && ClassUtils.isUserLevelMethod(method)) {
                return opDef;
            }
        }

        return null;
    }

    /**
     * Subclasses need to implement this to return the caching attribute
     * for the given method, if any.
     *
     * @param method the method to retrieve the attribute for
     * @return all caching attribute associated with this method
     * (or {@code null} if none)
     */
    protected abstract Collection<CacheOperation> findCacheOperations(Class<?> targetClass, Method method);

    /**
     * Subclasses need to implement this to return the caching attribute
     * for the given class, if any.
     *
     * @param clazz the class to retrieve the attribute for
     * @return all caching attribute associated with this class
     * (or {@code null} if none)
     */
    protected abstract Collection<CacheOperation> findCacheOperations(Class<?> clazz);

    /**
     * Should only public methods be allowed to have caching semantics?
     * <p>The default implementation returns {@code false}.
     */
    protected boolean allowPublicMethodsOnly() {
        return false;
    }

}