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
28 package org.apache.http.protocol;
29
30 import org.apache.http.annotation.NotThreadSafe;
31
32 /**
33 * {@link HttpContext} implementation that delegates resolution of an attribute
34 * to the given default {@link HttpContext} instance if the attribute is not
35 * present in the local one. The state of the local context can be mutated,
36 * whereas the default context is treated as read-only.
37 *
38 * @since 4.0
39 */
40 @NotThreadSafe
41 public final class DefaultedHttpContext implements HttpContext {
42
43 private final HttpContext local;
44 private final HttpContext defaults;
45
46 public DefaultedHttpContext(final HttpContext local, final HttpContext defaults) {
47 super();
48 if (local == null) {
49 throw new IllegalArgumentException("HTTP context may not be null");
50 }
51 this.local = local;
52 this.defaults = defaults;
53 }
54
55 public Object getAttribute(final String id) {
56 Object obj = this.local.getAttribute(id);
57 if (obj == null) {
58 return this.defaults.getAttribute(id);
59 } else {
60 return obj;
61 }
62 }
63
64 public Object removeAttribute(final String id) {
65 return this.local.removeAttribute(id);
66 }
67
68 public void setAttribute(final String id, final Object obj) {
69 this.local.setAttribute(id, obj);
70 }
71
72 public HttpContext getDefaults() {
73 return this.defaults;
74 }
75
76 @Override
77 public String toString() {
78 StringBuilder buf = new StringBuilder();
79 buf.append("[local: ").append(this.local);
80 buf.append("defaults: ").append(this.defaults);
81 buf.append("]");
82 return buf.toString();
83 }
84
85 }