Java tutorial
/* * ==================================================================== * Licensed to the Apache Software Foundation (ASF) under one * or more contributor license agreements. See the NOTICE file * distributed with this work for additional information * regarding copyright ownership. The ASF licenses this file * to you 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. * ==================================================================== * * This software consists of voluntary contributions made by many * individuals on behalf of the Apache Software Foundation. For more * information on the Apache Software Foundation, please see * <http://www.apache.org/>. * */ package org.apache.http.client.cache; import java.io.IOException; /** * Used for atomically updating entries in a {@link HttpCacheStorage} * implementation. The current entry (if any) is fed into an implementation * of this interface, and the new, possibly updated entry (if any) * should be returned. */ public interface HttpCacheUpdateCallback { /** * Returns the new cache entry that should replace an existing one. * * @param existing * the cache entry currently in-place in the cache, possibly * <code>null</code> if nonexistent * @return the cache entry that should replace it, again, * possibly <code>null</code> if the entry should be deleted * * @since 4.1 */ HttpCacheEntry update(HttpCacheEntry existing) throws IOException; }