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| 1 | +/* | |
| 2 | + * Copyright (c) 2003, 2008, Oracle and/or its affiliates. All rights reserved. | |
| 3 | + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. | |
| 4 | + * | |
| 5 | + * This code is free software; you can redistribute it and/or modify it | |
| 6 | + * under the terms of the GNU General Public License version 2 only, as | |
| 7 | + * published by the Free Software Foundation. Oracle designates this | |
| 8 | + * particular file as subject to the "Classpath" exception as provided | |
| 9 | + * by Oracle in the LICENSE file that accompanied this code. | |
| 10 | + * | |
| 11 | + * This code is distributed in the hope that it will be useful, but WITHOUT | |
| 12 | + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
| 13 | + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
| 14 | + * version 2 for more details (a copy is included in the LICENSE file that | |
| 15 | + * accompanied this code). | |
| 16 | + * | |
| 17 | + * You should have received a copy of the GNU General Public License version | |
| 18 | + * 2 along with this work; if not, write to the Free Software Foundation, | |
| 19 | + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. | |
| 20 | + * | |
| 21 | + * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA | |
| 22 | + * or visit www.oracle.com if you need additional information or have any | |
| 23 | + * questions. | |
| 24 | + */ | |
| 25 | + | |
| 26 | +package java.net; | |
| 27 | + | |
| 28 | +import java.io.IOException; | |
| 29 | +import java.util.Map; | |
| 30 | +import java.util.List; | |
| 31 | +import sun.security.util.SecurityConstants; | |
| 32 | + | |
| 33 | +/** | |
| 34 | + * Represents implementations of URLConnection caches. An instance of | |
| 35 | + * such a class can be registered with the system by doing | |
| 36 | + * ResponseCache.setDefault(ResponseCache), and the system will call | |
| 37 | + * this object in order to: | |
| 38 | + * | |
| 39 | + * <ul><li>store resource data which has been retrieved from an | |
| 40 | + * external source into the cache</li> | |
| 41 | + * <li>try to fetch a requested resource that may have been | |
| 42 | + * stored in the cache</li> | |
| 43 | + * </ul> | |
| 44 | + * | |
| 45 | + * The ResponseCache implementation decides which resources | |
| 46 | + * should be cached, and for how long they should be cached. If a | |
| 47 | + * request resource cannot be retrieved from the cache, then the | |
| 48 | + * protocol handlers will fetch the resource from its original | |
| 49 | + * location. | |
| 50 | + * | |
| 51 | + * The settings for URLConnection#useCaches controls whether the | |
| 52 | + * protocol is allowed to use a cached response. | |
| 53 | + * | |
| 54 | + * For more information on HTTP caching, see <a | |
| 55 | + * href="http://www.ietf.org/rfc/rfc2616.txt"><i>RFC 2616: Hypertext | |
| 56 | + * Transfer Protocol -- HTTP/1.1</i></a> | |
| 57 | + * | |
| 58 | + * @author Yingxian Wang | |
| 59 | + * @since 1.5 | |
| 60 | + */ | |
| 61 | +public abstract class ResponseCache { | |
| 62 | + | |
| 63 | + /** | |
| 64 | + * The system wide cache that provides access to a url | |
| 65 | + * caching mechanism. | |
| 66 | + * | |
| 67 | + * @see #setDefault(ResponseCache) | |
| 68 | + * @see #getDefault() | |
| 69 | + */ | |
| 70 | + private static ResponseCache theResponseCache; | |
| 71 | + | |
| 72 | + /** | |
| 73 | + * Gets the system-wide response cache. | |
| 74 | + * | |
| 75 | + * @throws SecurityException | |
| 76 | + * If a security manager has been installed and it denies | |
| 77 | + * {@link NetPermission}<tt>("getResponseCache")</tt> | |
| 78 | + * | |
| 79 | + * @see #setDefault(ResponseCache) | |
| 80 | + * @return the system-wide <code>ResponseCache</code> | |
| 81 | + * @since 1.5 | |
| 82 | + */ | |
| 83 | + public synchronized static ResponseCache getDefault() { | |
| 84 | + SecurityManager sm = System.getSecurityManager(); | |
| 85 | + if (sm != null) { | |
| 86 | + sm.checkPermission(SecurityConstants.GET_RESPONSECACHE_PERMISSION); | |
| 87 | + } | |
| 88 | + return theResponseCache; | |
| 89 | + } | |
| 90 | + | |
| 91 | + /** | |
| 92 | + * Sets (or unsets) the system-wide cache. | |
| 93 | + * | |
| 94 | + * Note: non-standard procotol handlers may ignore this setting. | |
| 95 | + * | |
| 96 | + * @param responseCache The response cache, or | |
| 97 | + * <code>null</code> to unset the cache. | |
| 98 | + * | |
| 99 | + * @throws SecurityException | |
| 100 | + * If a security manager has been installed and it denies | |
| 101 | + * {@link NetPermission}<tt>("setResponseCache")</tt> | |
| 102 | + * | |
| 103 | + * @see #getDefault() | |
| 104 | + * @since 1.5 | |
| 105 | + */ | |
| 106 | + public synchronized static void setDefault(ResponseCache responseCache) { | |
| 107 | + SecurityManager sm = System.getSecurityManager(); | |
| 108 | + if (sm != null) { | |
| 109 | + sm.checkPermission(SecurityConstants.SET_RESPONSECACHE_PERMISSION); | |
| 110 | + } | |
| 111 | + theResponseCache = responseCache; | |
| 112 | + } | |
| 113 | + | |
| 114 | + /** | |
| 115 | + * Retrieve the cached response based on the requesting uri, | |
| 116 | + * request method and request headers. Typically this method is | |
| 117 | + * called by the protocol handler before it sends out the request | |
| 118 | + * to get the network resource. If a cached response is returned, | |
| 119 | + * that resource is used instead. | |
| 120 | + * | |
| 121 | + * @param uri a <code>URI</code> used to reference the requested | |
| 122 | + * network resource | |
| 123 | + * @param rqstMethod a <code>String</code> representing the request | |
| 124 | + * method | |
| 125 | + * @param rqstHeaders - a Map from request header | |
| 126 | + * field names to lists of field values representing | |
| 127 | + * the current request headers | |
| 128 | + * @return a <code>CacheResponse</code> instance if available | |
| 129 | + * from cache, or null otherwise | |
| 130 | + * @throws IOException if an I/O error occurs | |
| 131 | + * @throws IllegalArgumentException if any one of the arguments is null | |
| 132 | + * | |
| 133 | + * @see java.net.URLConnection#setUseCaches(boolean) | |
| 134 | + * @see java.net.URLConnection#getUseCaches() | |
| 135 | + * @see java.net.URLConnection#setDefaultUseCaches(boolean) | |
| 136 | + * @see java.net.URLConnection#getDefaultUseCaches() | |
| 137 | + */ | |
| 138 | + public abstract CacheResponse | |
| 139 | + get(URI uri, String rqstMethod, Map<String, List<String>> rqstHeaders) | |
| 140 | + throws IOException; | |
| 141 | + | |
| 142 | + /** | |
| 143 | + * The protocol handler calls this method after a resource has | |
| 144 | + * been retrieved, and the ResponseCache must decide whether or | |
| 145 | + * not to store the resource in its cache. If the resource is to | |
| 146 | + * be cached, then put() must return a CacheRequest object which | |
| 147 | + * contains an OutputStream that the protocol handler will | |
| 148 | + * use to write the resource into the cache. If the resource is | |
| 149 | + * not to be cached, then put must return null. | |
| 150 | + * | |
| 151 | + * @param uri a <code>URI</code> used to reference the requested | |
| 152 | + * network resource | |
| 153 | + * @param conn - a URLConnection instance that is used to fetch | |
| 154 | + * the response to be cached | |
| 155 | + * @return a <code>CacheRequest</code> for recording the | |
| 156 | + * response to be cached. Null return indicates that | |
| 157 | + * the caller does not intend to cache the response. | |
| 158 | + * @throws IOException if an I/O error occurs | |
| 159 | + * @throws IllegalArgumentException if any one of the arguments is | |
| 160 | + * null | |
| 161 | + */ | |
| 162 | + public abstract CacheRequest put(URI uri, URLConnection conn) throws IOException; | |
| 163 | +} | |