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