org.podcastpedia.web.caching.EnhancedDefaultKeyGenerator.java Source code

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Here is the source code for org.podcastpedia.web.caching.EnhancedDefaultKeyGenerator.java

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/*
 * Copyright 2002-2011 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.podcastpedia.web.caching;

import java.lang.reflect.Method;
import java.util.HashSet;

import org.springframework.cache.interceptor.KeyGenerator;

/**
 * Default key generator. Returns {@value #NO_PARAM_KEY} if no
 * parameters are provided, the parameter itself if only one is given or
 * a hash code computed from all given parameters' hash code values.
 * Uses the constant value {@value #NULL_PARAM_KEY} for any
 * {@code null} parameters given.
 *
 * @author Costin Leau
 * @author Chris Beams
 * @since 3.1
 */
public class EnhancedDefaultKeyGenerator implements KeyGenerator {

    public static final int NO_PARAM_KEY = 0;
    public static final int NULL_PARAM_KEY = 53;

    private static final HashSet<Class<?>> WRAPPER_TYPES = getWrapperTypes();

    public Object generate(Object target, Method method, Object... params) {
        if (params.length == 1 && isWrapperType(params[0].getClass())) {
            return (params[0] == null ? NULL_PARAM_KEY : params[0]);
        }
        if (params.length == 0) {
            return NO_PARAM_KEY;
        }
        int hashCode = 17;
        for (Object object : params) {
            hashCode = 31 * hashCode + (object == null ? NULL_PARAM_KEY : object.hashCode());
        }
        return Integer.valueOf(hashCode);
    }

    public static boolean isWrapperType(Class<?> clazz) {
        return WRAPPER_TYPES.contains(clazz);
    }

    private static HashSet<Class<?>> getWrapperTypes() {
        HashSet<Class<?>> ret = new HashSet<Class<?>>();
        ret.add(Boolean.class);
        ret.add(Character.class);
        ret.add(Byte.class);
        ret.add(Short.class);
        ret.add(Integer.class);
        ret.add(Long.class);
        ret.add(Float.class);
        ret.add(Double.class);
        ret.add(Void.class);
        return ret;
    }

}