HttpRequestExecutor.java revision 417f3b92ba4549b2f22340e3107d869d2b9c5bb8 
1/*
2 * $HeadURL: http://svn.apache.org/repos/asf/httpcomponents/httpcore/trunk/module-main/src/main/java/org/apache/http/protocol/HttpRequestExecutor.java $
3 * $Revision: 576073 $
4 * $Date: 2007-09-16 03:53:13 -0700 (Sun, 16 Sep 2007) $
5 *
6 * ====================================================================
7 * Licensed to the Apache Software Foundation (ASF) under one
8 * or more contributor license agreements.  See the NOTICE file
9 * distributed with this work for additional information
10 * regarding copyright ownership.  The ASF licenses this file
11 * to you under the Apache License, Version 2.0 (the
12 * "License"); you may not use this file except in compliance
13 * with the License.  You may obtain a copy of the License at
14 *
15 *   http://www.apache.org/licenses/LICENSE-2.0
16 *
17 * Unless required by applicable law or agreed to in writing,
18 * software distributed under the License is distributed on an
19 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
20 * KIND, either express or implied.  See the License for the
21 * specific language governing permissions and limitations
22 * under the License.
23 * ====================================================================
24 *
25 * This software consists of voluntary contributions made by many
26 * individuals on behalf of the Apache Software Foundation.  For more
27 * information on the Apache Software Foundation, please see
28 * <http://www.apache.org/>.
29 *
30 */
31
32package org.apache.http.protocol;
33
34import java.io.IOException;
35import java.net.ProtocolException;
36
37import org.apache.http.HttpClientConnection;
38import org.apache.http.HttpEntityEnclosingRequest;
39import org.apache.http.HttpException;
40import org.apache.http.HttpRequest;
41import org.apache.http.HttpResponse;
42import org.apache.http.HttpStatus;
43import org.apache.http.HttpVersion;
44import org.apache.http.ProtocolVersion;
45import org.apache.http.params.CoreProtocolPNames;
46
47/**
48 * Sends HTTP requests and receives the responses.
49 * Takes care of request preprocessing and response postprocessing
50 * by the respective interceptors.
51 *
52 * @author <a href="mailto:oleg at ural.ru">Oleg Kalnichevski</a>
53 *
54 * @version $Revision: 576073 $
55 *
56 * @since 4.0
57 */
58public class HttpRequestExecutor {
59
60    /**
61     * Create a new request executor.
62     */
63    public HttpRequestExecutor() {
64        super();
65    }
66
67    /**
68     * Decide whether a response comes with an entity.
69     * The implementation in this class is based on RFC 2616.
70     * Unknown methods and response codes are supposed to
71     * indicate responses with an entity.
72     * <br/>
73     * Derived executors can override this method to handle
74     * methods and response codes not specified in RFC 2616.
75     *
76     * @param request   the request, to obtain the executed method
77     * @param response  the response, to obtain the status code
78     */
79    protected boolean canResponseHaveBody(final HttpRequest request,
80                                          final HttpResponse response) {
81
82        if ("HEAD".equalsIgnoreCase(request.getRequestLine().getMethod())) {
83            return false;
84        }
85        int status = response.getStatusLine().getStatusCode();
86        return status >= HttpStatus.SC_OK
87            && status != HttpStatus.SC_NO_CONTENT
88            && status != HttpStatus.SC_NOT_MODIFIED
89            && status != HttpStatus.SC_RESET_CONTENT;
90    }
91
92    /**
93     * Synchronously send a request and obtain the response.
94     *
95     * @param request   the request to send. It will be preprocessed.
96     * @param conn      the open connection over which to send
97     *
98     * @return  the response to the request, postprocessed
99     *
100     * @throws HttpException      in case of a protocol or processing problem
101     * @throws IOException        in case of an I/O problem
102     */
103    public HttpResponse execute(
104            final HttpRequest request,
105            final HttpClientConnection conn,
106            final HttpContext context)
107                throws IOException, HttpException {
108        if (request == null) {
109            throw new IllegalArgumentException("HTTP request may not be null");
110        }
111        if (conn == null) {
112            throw new IllegalArgumentException("Client connection may not be null");
113        }
114        if (context == null) {
115            throw new IllegalArgumentException("HTTP context may not be null");
116        }
117
118        try {
119            HttpResponse response = doSendRequest(request, conn, context);
120            if (response == null) {
121                response = doReceiveResponse(request, conn, context);
122            }
123            return response;
124        } catch (IOException ex) {
125            conn.close();
126            throw ex;
127        } catch (HttpException ex) {
128            conn.close();
129            throw ex;
130        } catch (RuntimeException ex) {
131            conn.close();
132            throw ex;
133        }
134    }
135
136    /**
137     * Prepare a request for sending.
138     *
139     * @param request   the request to prepare
140     * @param processor the processor to use
141     * @param context   the context for sending the request
142     *
143     * @throws HttpException      in case of a protocol or processing problem
144     * @throws IOException        in case of an I/O problem
145     */
146    public void preProcess(
147            final HttpRequest request,
148            final HttpProcessor processor,
149            final HttpContext context)
150                throws HttpException, IOException {
151        if (request == null) {
152            throw new IllegalArgumentException("HTTP request may not be null");
153        }
154        if (processor == null) {
155            throw new IllegalArgumentException("HTTP processor may not be null");
156        }
157        if (context == null) {
158            throw new IllegalArgumentException("HTTP context may not be null");
159        }
160        processor.process(request, context);
161    }
162
163    /**
164     * Send a request over a connection.
165     * This method also handles the expect-continue handshake if necessary.
166     * If it does not have to handle an expect-continue handshake, it will
167     * not use the connection for reading or anything else that depends on
168     * data coming in over the connection.
169     *
170     * @param request   the request to send, already
171     *                  {@link #preProcess preprocessed}
172     * @param conn      the connection over which to send the request,
173     *                  already established
174     * @param context   the context for sending the request
175     *
176     * @return  a terminal response received as part of an expect-continue
177     *          handshake, or
178     *          <code>null</code> if the expect-continue handshake is not used
179     *
180     * @throws HttpException      in case of a protocol or processing problem
181     * @throws IOException        in case of an I/O problem
182     */
183    protected HttpResponse doSendRequest(
184            final HttpRequest request,
185            final HttpClientConnection conn,
186            final HttpContext context)
187                throws IOException, HttpException {
188        if (request == null) {
189            throw new IllegalArgumentException("HTTP request may not be null");
190        }
191        if (conn == null) {
192            throw new IllegalArgumentException("HTTP connection may not be null");
193        }
194        if (context == null) {
195            throw new IllegalArgumentException("HTTP context may not be null");
196        }
197
198        HttpResponse response = null;
199        context.setAttribute(ExecutionContext.HTTP_REQ_SENT, Boolean.FALSE);
200
201        conn.sendRequestHeader(request);
202        if (request instanceof HttpEntityEnclosingRequest) {
203            // Check for expect-continue handshake. We have to flush the
204            // headers and wait for an 100-continue response to handle it.
205            // If we get a different response, we must not send the entity.
206            boolean sendentity = true;
207            final ProtocolVersion ver =
208                request.getRequestLine().getProtocolVersion();
209            if (((HttpEntityEnclosingRequest) request).expectContinue() &&
210                !ver.lessEquals(HttpVersion.HTTP_1_0)) {
211
212                conn.flush();
213                // As suggested by RFC 2616 section 8.2.3, we don't wait for a
214                // 100-continue response forever. On timeout, send the entity.
215                int tms = request.getParams().getIntParameter(
216                        CoreProtocolPNames.WAIT_FOR_CONTINUE, 2000);
217
218                if (conn.isResponseAvailable(tms)) {
219                    response = conn.receiveResponseHeader();
220                    if (canResponseHaveBody(request, response)) {
221                        conn.receiveResponseEntity(response);
222                    }
223                    int status = response.getStatusLine().getStatusCode();
224                    if (status < 200) {
225                        if (status != HttpStatus.SC_CONTINUE) {
226                            throw new ProtocolException(
227                                    "Unexpected response: " + response.getStatusLine());
228                        }
229                        // discard 100-continue
230                        response = null;
231                    } else {
232                        sendentity = false;
233                    }
234                }
235            }
236            if (sendentity) {
237                conn.sendRequestEntity((HttpEntityEnclosingRequest) request);
238            }
239        }
240        conn.flush();
241        context.setAttribute(ExecutionContext.HTTP_REQ_SENT, Boolean.TRUE);
242        return response;
243    }
244
245    /**
246     * Wait for and receive a response.
247     * This method will automatically ignore intermediate responses
248     * with status code 1xx.
249     *
250     * @param request   the request for which to obtain the response
251     * @param conn      the connection over which the request was sent
252     * @param context   the context for receiving the response
253     *
254     * @return  the final response, not yet post-processed
255     *
256     * @throws HttpException      in case of a protocol or processing problem
257     * @throws IOException        in case of an I/O problem
258     */
259    protected HttpResponse doReceiveResponse(
260            final HttpRequest          request,
261            final HttpClientConnection conn,
262            final HttpContext          context)
263                throws HttpException, IOException {
264        if (request == null) {
265            throw new IllegalArgumentException("HTTP request may not be null");
266        }
267        if (conn == null) {
268            throw new IllegalArgumentException("HTTP connection may not be null");
269        }
270        if (context == null) {
271            throw new IllegalArgumentException("HTTP context may not be null");
272        }
273
274        HttpResponse response = null;
275        int statuscode = 0;
276
277        while (response == null || statuscode < HttpStatus.SC_OK) {
278
279            response = conn.receiveResponseHeader();
280            if (canResponseHaveBody(request, response)) {
281                conn.receiveResponseEntity(response);
282            }
283            statuscode = response.getStatusLine().getStatusCode();
284
285        } // while intermediate response
286
287        return response;
288
289    }
290
291    /**
292     * Finish a response.
293     * This includes post-processing of the response object.
294     * It does <i>not</i> read the response entity, if any.
295     * It does <i>not</i> allow for immediate re-use of the
296     * connection over which the response is coming in.
297     *
298     * @param response  the response object to finish
299     * @param processor the processor to use
300     * @param context   the context for post-processing the response
301     *
302     * @throws HttpException      in case of a protocol or processing problem
303     * @throws IOException        in case of an I/O problem
304     */
305    public void postProcess(
306            final HttpResponse response,
307            final HttpProcessor processor,
308            final HttpContext context)
309                throws HttpException, IOException {
310        if (response == null) {
311            throw new IllegalArgumentException("HTTP response may not be null");
312        }
313        if (processor == null) {
314            throw new IllegalArgumentException("HTTP processor may not be null");
315        }
316        if (context == null) {
317            throw new IllegalArgumentException("HTTP context may not be null");
318        }
319        processor.process(response, context);
320    }
321
322} // class HttpRequestExecutor
323