| /* |
| * Copyright (c) 2003, 2013, Oracle and/or its affiliates. All rights reserved. |
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| * |
| * This code is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 only, as |
| * published by the Free Software Foundation. Oracle designates this |
| * particular file as subject to the "Classpath" exception as provided |
| * by Oracle in the LICENSE file that accompanied this code. |
| * |
| * This code is distributed in the hope that it will be useful, but WITHOUT |
| * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| * version 2 for more details (a copy is included in the LICENSE file that |
| * accompanied this code). |
| * |
| * You should have received a copy of the GNU General Public License version |
| * 2 along with this work; if not, write to the Free Software Foundation, |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| */ |
| |
| package java.net; |
| |
| import java.io.IOException; |
| import java.util.Map; |
| import java.util.List; |
| import sun.security.util.SecurityConstants; |
| |
| /** |
| * Represents implementations of URLConnection caches. An instance of |
| * such a class can be registered with the system by doing |
| * ResponseCache.setDefault(ResponseCache), and the system will call |
| * this object in order to: |
| * |
| * <ul><li>store resource data which has been retrieved from an |
| * external source into the cache</li> |
| * <li>try to fetch a requested resource that may have been |
| * stored in the cache</li> |
| * </ul> |
| * |
| * The ResponseCache implementation decides which resources |
| * should be cached, and for how long they should be cached. If a |
| * request resource cannot be retrieved from the cache, then the |
| * protocol handlers will fetch the resource from its original |
| * location. |
| * |
| * The settings for URLConnection#useCaches controls whether the |
| * protocol is allowed to use a cached response. |
| * |
| * For more information on HTTP caching, see <a |
| * href="http://www.ietf.org/rfc/rfc2616.txt"><i>RFC 2616: Hypertext |
| * Transfer Protocol -- HTTP/1.1</i></a> |
| * |
| * @author Yingxian Wang |
| * @since 1.5 |
| */ |
| public abstract class ResponseCache { |
| |
| /** |
| * The system wide cache that provides access to a url |
| * caching mechanism. |
| * |
| * @see #setDefault(ResponseCache) |
| * @see #getDefault() |
| */ |
| private static ResponseCache theResponseCache; |
| |
| /** |
| * Gets the system-wide response cache. |
| * |
| * @throws SecurityException |
| * If a security manager has been installed and it denies |
| * {@link NetPermission}{@code ("getResponseCache")} |
| * |
| * @see #setDefault(ResponseCache) |
| * @return the system-wide {@code ResponseCache} |
| * @since 1.5 |
| */ |
| public static synchronized ResponseCache getDefault() { |
| SecurityManager sm = System.getSecurityManager(); |
| if (sm != null) { |
| sm.checkPermission(SecurityConstants.GET_RESPONSECACHE_PERMISSION); |
| } |
| return theResponseCache; |
| } |
| |
| /** |
| * Sets (or unsets) the system-wide cache. |
| * |
| * Note: non-standard procotol handlers may ignore this setting. |
| * |
| * @param responseCache The response cache, or |
| * {@code null} to unset the cache. |
| * |
| * @throws SecurityException |
| * If a security manager has been installed and it denies |
| * {@link NetPermission}{@code ("setResponseCache")} |
| * |
| * @see #getDefault() |
| * @since 1.5 |
| */ |
| public static synchronized void setDefault(ResponseCache responseCache) { |
| SecurityManager sm = System.getSecurityManager(); |
| if (sm != null) { |
| sm.checkPermission(SecurityConstants.SET_RESPONSECACHE_PERMISSION); |
| } |
| theResponseCache = responseCache; |
| } |
| |
| /** |
| * Retrieve the cached response based on the requesting uri, |
| * request method and request headers. Typically this method is |
| * called by the protocol handler before it sends out the request |
| * to get the network resource. If a cached response is returned, |
| * that resource is used instead. |
| * |
| * @param uri a {@code URI} used to reference the requested |
| * network resource |
| * @param rqstMethod a {@code String} representing the request |
| * method |
| * @param rqstHeaders - a Map from request header |
| * field names to lists of field values representing |
| * the current request headers |
| * @return a {@code CacheResponse} instance if available |
| * from cache, or null otherwise |
| * @throws IOException if an I/O error occurs |
| * @throws IllegalArgumentException if any one of the arguments is null |
| * |
| * @see java.net.URLConnection#setUseCaches(boolean) |
| * @see java.net.URLConnection#getUseCaches() |
| * @see java.net.URLConnection#setDefaultUseCaches(boolean) |
| * @see java.net.URLConnection#getDefaultUseCaches() |
| */ |
| public abstract CacheResponse |
| get(URI uri, String rqstMethod, Map<String, List<String>> rqstHeaders) |
| throws IOException; |
| |
| /** |
| * The protocol handler calls this method after a resource has |
| * been retrieved, and the ResponseCache must decide whether or |
| * not to store the resource in its cache. If the resource is to |
| * be cached, then put() must return a CacheRequest object which |
| * contains an OutputStream that the protocol handler will |
| * use to write the resource into the cache. If the resource is |
| * not to be cached, then put must return null. |
| * |
| * @param uri a {@code URI} used to reference the requested |
| * network resource |
| * @param conn - a URLConnection instance that is used to fetch |
| * the response to be cached |
| * @return a {@code CacheRequest} for recording the |
| * response to be cached. Null return indicates that |
| * the caller does not intend to cache the response. |
| * @throws IOException if an I/O error occurs |
| * @throws IllegalArgumentException if any one of the arguments is |
| * null |
| */ |
| public abstract CacheRequest put(URI uri, URLConnection conn) throws IOException; |
| } |