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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 | } | ||