Java tutorial
/* * Copyright 2002-2013 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 grails.plugin.cache; import java.io.Serializable; import java.lang.reflect.Method; import java.util.Arrays; import org.springframework.cache.interceptor.KeyGenerator; import org.springframework.util.Assert; import org.springframework.util.StringUtils; /** * Copy of Spring 4.0's {@link org.springframework.cache.interceptor.SimpleKeyGenerator} and {@link org.springframework.cache.interceptor.SimpleKey} * * Simple key generator. Returns the parameter itself if a single non-null value * is given, otherwise returns a {@link SimpleKey} of the parameters. * * <p>Unlike {@link DefaultKeyGenerator}, no collisions will occur with the keys * generated by this class. The returned {@link SimpleKey} object can be safely * used with a {@link org.springframework.cache.concurrent.ConcurrentMapCache}, * however, might not be suitable for all {@link org.springframework.cache.Cache} * implementations. * * @author Phillip Webb * @since 4.0 * @see SimpleKey * @see DefaultKeyGenerator * @see org.springframework.cache.annotation.CachingConfigurer */ public class SimpleKeyGenerator implements KeyGenerator { /** * A simple key as returned from the {@link SimpleKeyGenerator}. * * @author Phillip Webb * @since 4.0 * @see SimpleKeyGenerator */ @SuppressWarnings("serial") public static final class SimpleKey implements Serializable { public static final SimpleKey EMPTY = new SimpleKey(); private final Object[] params; /** * Create a new {@link SimpleKey} instance. * @param elements the elements of the key */ public SimpleKey(Object... elements) { Assert.notNull(elements, "Elements must not be null"); this.params = new Object[elements.length]; System.arraycopy(elements, 0, this.params, 0, elements.length); } @Override public boolean equals(Object obj) { return (this == obj || (obj instanceof SimpleKey && Arrays.deepEquals(this.params, ((SimpleKey) obj).params))); } @Override public int hashCode() { return Arrays.deepHashCode(this.params); } @Override public String toString() { return "SimpleKey [" + StringUtils.arrayToCommaDelimitedString(this.params) + "]"; } } @Override public Object generate(Object target, Method method, Object... params) { if (params.length == 0) { return SimpleKey.EMPTY; } if (params.length == 1) { Object param = params[0]; if (param != null && !param.getClass().isArray()) { return param; } } return new SimpleKey(params); } }