1 /*
2 * ====================================================================
3 * Licensed to the Apache Software Foundation (ASF) under one
4 * or more contributor license agreements. See the NOTICE file
5 * distributed with this work for additional information
6 * regarding copyright ownership. The ASF licenses this file
7 * to you under the Apache License, Version 2.0 (the
8 * "License"); you may not use this file except in compliance
9 * with the License. You may obtain a copy of the License at
10 *
11 * http://www.apache.org/licenses/LICENSE-2.0
12 *
13 * Unless required by applicable law or agreed to in writing,
14 * software distributed under the License is distributed on an
15 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
16 * KIND, either express or implied. See the License for the
17 * specific language governing permissions and limitations
18 * under the License.
19 * ====================================================================
20 *
21 * This software consists of voluntary contributions made by many
22 * individuals on behalf of the Apache Software Foundation. For more
23 * information on the Apache Software Foundation, please see
24 * <http://www.apache.org/>.
25 *
26 */
27 package org.apache.hc.client5.http.impl.cache;
28
29 import java.io.IOException;
30 import java.time.Instant;
31
32 import org.apache.hc.core5.annotation.Contract;
33 import org.apache.hc.core5.annotation.ThreadingBehavior;
34 import org.apache.hc.core5.http.EntityDetails;
35 import org.apache.hc.core5.http.HttpException;
36 import org.apache.hc.core5.http.HttpHeaders;
37 import org.apache.hc.core5.http.HttpResponse;
38 import org.apache.hc.core5.http.HttpResponseInterceptor;
39 import org.apache.hc.core5.http.HttpStatus;
40 import org.apache.hc.core5.http.message.BasicHeader;
41 import org.apache.hc.core5.http.protocol.HttpContext;
42
43 /**
44 * This response interceptor removes common {@literal Content-} headers from the 304
45 * response messages based on the provision of the HTTP specification that 304
46 * status code represents a confirmation that the requested resource content has
47 * not changed since its retrieval or the last update and adds {@literal Date}
48 * header if it is not present in the response message..
49 */
50 @Contract(threading = ThreadingBehavior.IMMUTABLE)
51 class ResponseCacheConformance implements HttpResponseInterceptor {
52
53 public static final ResponseCacheConformance INSTANCE = new ResponseCacheConformance();
54
55 private final static String[] DISALLOWED_ENTITY_HEADERS = {
56 HttpHeaders.CONTENT_ENCODING,
57 HttpHeaders.CONTENT_LANGUAGE,
58 HttpHeaders.CONTENT_LENGTH,
59 HttpHeaders.CONTENT_MD5,
60 HttpHeaders.CONTENT_RANGE,
61 HttpHeaders.CONTENT_TYPE
62 };
63
64 @Override
65 public void process(final HttpResponse response,
66 final EntityDetails entity,
67 final HttpContext context) throws HttpException, IOException {
68 if (response.getCode() == HttpStatus.SC_NOT_MODIFIED) {
69 for (final String headerName : DISALLOWED_ENTITY_HEADERS) {
70 response.removeHeaders(headerName);
71 }
72 }
73 if (!response.containsHeader(HttpHeaders.DATE)) {
74 response.addHeader(new BasicHeader(HttpHeaders.DATE, Instant.now()));
75 }
76 }
77
78 }