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.impl.client;
29
30 import java.io.IOException;
31
32 import org.apache.http.HttpEntity;
33 import org.apache.http.HttpResponse;
34 import org.apache.http.StatusLine;
35 import org.apache.http.annotation.Contract;
36 import org.apache.http.annotation.ThreadingBehavior;
37 import org.apache.http.client.HttpResponseException;
38 import org.apache.http.client.ResponseHandler;
39 import org.apache.http.util.EntityUtils;
40
41 /**
42 * A generic {@link ResponseHandler} that works with the response entity
43 * for successful (2xx) responses. If the response code was >= 300, the response
44 * body is consumed and an {@link HttpResponseException} is thrown.
45 * <p>
46 * If this is used with
47 * {@link org.apache.http.client.HttpClient#execute(
48 * org.apache.http.client.methods.HttpUriRequest, ResponseHandler)},
49 * HttpClient may handle redirects (3xx responses) internally.
50 * </p>
51 *
52 * @since 4.4
53 */
54 @Contract(threading = ThreadingBehavior.IMMUTABLE)
55 public abstract class AbstractResponseHandler<T> implements ResponseHandler<T> {
56
57 /**
58 * Read the entity from the response body and pass it to the entity handler
59 * method if the response was successful (a 2xx status code). If no response
60 * body exists, this returns null. If the response was unsuccessful (>= 300
61 * status code), throws an {@link HttpResponseException}.
62 */
63 @Override
64 public T handleResponse(final HttpResponse response)
65 throws HttpResponseException, IOException {
66 final StatusLine statusLine = response.getStatusLine();
67 final HttpEntity entity = response.getEntity();
68 if (statusLine.getStatusCode() >= 300) {
69 EntityUtils.consume(entity);
70 throw new HttpResponseException(statusLine.getStatusCode(),
71 statusLine.getReasonPhrase());
72 }
73 return entity == null ? null : handleEntity(entity);
74 }
75
76 /**
77 * Handle the response entity and transform it into the actual response
78 * object.
79 */
80 public abstract T handleEntity(HttpEntity entity) throws IOException;
81
82 }