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
31 import org.apache.hc.core5.annotation.Contract;
32 import org.apache.hc.core5.annotation.ThreadingBehavior;
33 import org.apache.hc.core5.http.EntityDetails;
34 import org.apache.hc.core5.http.HttpException;
35 import org.apache.hc.core5.http.HttpHeaders;
36 import org.apache.hc.core5.http.HttpResponse;
37 import org.apache.hc.core5.http.HttpResponseInterceptor;
38 import org.apache.hc.core5.http.ProtocolVersion;
39 import org.apache.hc.core5.http.protocol.HttpContext;
40
41 /**
42 * This response interceptor adds {@literal VIA} header to all incoming
43 * response messages dispatched through the caching layer.
44 */
45 @Contract(threading = ThreadingBehavior.IMMUTABLE)
46 class ResponseViaCache implements HttpResponseInterceptor {
47
48 /**
49 * Default instance of {@link ResponseViaCache}.
50 */
51 public static final ResponseViaCache INSTANCE = new ResponseViaCache();
52
53 @Override
54 public void process(final HttpResponse response,
55 final EntityDetails entity,
56 final HttpContext context) throws HttpException, IOException {
57 final ProtocolVersion protocolVersion = context.getProtocolVersion();
58 response.addHeader(HttpHeaders.VIA, ViaCacheGenerator.INSTANCE.lookup(protocolVersion));
59 }
60
61 }