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    1   /*
    2    * $Header: /home/jerenkrantz/tmp/commons/commons-convert/cvs/home/cvs/jakarta-commons//httpclient/src/java/org/apache/commons/httpclient/methods/HeadMethod.java,v 1.29 2004/06/13 20:22:19 olegk Exp $
    3    * $Revision: 480424 $
    4    * $Date: 2006-11-29 06:56:49 +0100 (Wed, 29 Nov 2006) $
    5    *
    6    * ====================================================================
    7    *
    8    *  Licensed to the Apache Software Foundation (ASF) under one or more
    9    *  contributor license agreements.  See the NOTICE file distributed with
    10   *  this work for additional information regarding copyright ownership.
    11   *  The ASF licenses this file to You under the Apache License, Version 2.0
    12   *  (the "License"); you may not use this file except in compliance with
    13   *  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, software
    18   *  distributed under the License is distributed on an "AS IS" BASIS,
    19   *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    20   *  See the License for the specific language governing permissions and
    21   *  limitations under the License.
    22   * ====================================================================
    23   *
    24   * This software consists of voluntary contributions made by many
    25   * individuals on behalf of the Apache Software Foundation.  For more
    26   * information on the Apache Software Foundation, please see
    27   * <http://www.apache.org/>.
    28   *
    29   */
    30
    31  package org.apache.commons.httpclient.methods;
    32
    33  import java.io.IOException;
    34
    35  import org.apache.commons.httpclient.HttpConnection;
    36  import org.apache.commons.httpclient.HttpException;
    37  import org.apache.commons.httpclient.HttpMethodBase;
    38  import org.apache.commons.httpclient.HttpState;
    39  import org.apache.commons.httpclient.ProtocolException;
    40  import org.apache.commons.httpclient.params.HttpMethodParams;
    41  import org.apache.commons.logging.Log;
    42  import org.apache.commons.logging.LogFactory;
    43
    44  /**
    45   * Implements the HTTP HEAD method.
    46   * <p>
    47   * The HTTP HEAD method is defined in section 9.4 of
    48   * <a href="http://www.ietf.org/rfc/rfc2616.txt">RFC2616</a>:
    49   * <blockquote>
    50   * The HEAD method is identical to GET except that the server MUST NOT
    51   * return a message-body in the response. The metainformation contained
    52   * in the HTTP headers in response to a HEAD request SHOULD be identical
    53   * to the information sent in response to a GET request. This method can
    54   * be used for obtaining metainformation about the entity implied by the
    55   * request without transferring the entity-body itself. This method is
    56   * often used for testing hypertext links for validity, accessibility,
    57   * and recent modification.
    58   * </blockquote>
    59   * </p>
    60   *
    61   * @author <a href="mailto:remm@apache.org">Remy Maucherat</a>
    62   * @author <a href="mailto:mbowler@GargoyleSoftware.com">Mike Bowler</a>
    63   * @author <a href="mailto:jsdever@apache.org">Jeff Dever</a>
    64   * @author <a href="mailto:oleg@ural.ru">oleg Kalnichevski</a>
    65   *
    66   * @version $Revision: 480424 $
    67   * @since 1.0
    68   */
    69  public class HeadMethod extends HttpMethodBase {
    70      //~ Static variables/initializers
    71
    72      /** Log object for this class. */
    73      private static final Log LOG = LogFactory.getLog(HeadMethod.class);
    74
    75      //~ Constructors
    76
    77      /**
    78       * No-arg constructor.
    79       *
    80       * @since 1.0
    81       */
    82      public HeadMethod() {
    83          setFollowRedirects(true);
    84      }
    85
    86      /**
    87       * Constructor specifying a URI.
    88       *
    89       * @param uri either an absolute or relative URI
    90       *
    91       * @since 1.0
    92       */
    93      public HeadMethod(String uri) {
    94          super(uri);
    95          setFollowRedirects(true);
    96      }
    97
    98      //~ Methods
    99
    100     /**
    101      * Returns <tt>"HEAD"</tt>.
    102      *
    103      * @return <tt>"HEAD"</tt>
    104      *
    105      * @since 2.0
    106      */
    107     public String getName() {
    108         return "HEAD";
    109     }
    110
    111     /**
    112      * Recycles the HTTP method so that it can be used again.
    113      * Note that all of the instance variables will be reset
    114      * once this method has been called. This method will also
    115      * release the connection being used by this HTTP method.
    116      *
    117      * @see #releaseConnection()
    118      *
    119      * @since 1.0
    120      *
    121      * @deprecated no longer supported and will be removed in the future
    122      *             version of HttpClient
    123      */
    124     public void recycle() {
    125         super.recycle();
    126         setFollowRedirects(true);
    127     }
    128
    129     /**
    130      * Overrides {@link HttpMethodBase} method to <i>not</i> read a response
    131      * body, despite the presence of a <tt>Content-Length</tt> or
    132      * <tt>Transfer-Encoding</tt> header.
    133      *
    134      * @param state the {@link HttpState state} information associated with this method
    135      * @param conn the {@link HttpConnection connection} used to execute
    136      *        this HTTP method
    137      *
    138      * @throws IOException if an I/O (transport) error occurs. Some transport exceptions
    139      *                     can be recovered from.
    140      * @throws HttpException  if a protocol exception occurs. Usually protocol exceptions
    141      *                    cannot be recovered from.
    142      *
    143      * @see #readResponse
    144      * @see #processResponseBody
    145      *
    146      * @since 2.0
    147      */
    148     protected void readResponseBody(HttpState state, HttpConnection conn)
    149     throws HttpException, IOException {
    150         LOG.trace(
    151             "enter HeadMethod.readResponseBody(HttpState, HttpConnection)");
    152
    153         int bodyCheckTimeout =
    154             getParams().getIntParameter(HttpMethodParams.HEAD_BODY_CHECK_TIMEOUT, -1);
    155
    156         if (bodyCheckTimeout < 0) {
    157             responseBodyConsumed();
    158         } else {
    159             if (LOG.isDebugEnabled()) {
    160                 LOG.debug("Check for non-compliant response body. Timeout in "
    161                  + bodyCheckTimeout + " ms");
    162             }
    163             boolean responseAvailable = false;
    164             try {
    165                 responseAvailable = conn.isResponseAvailable(bodyCheckTimeout);
    166             } catch (IOException e) {
    167                 LOG.debug("An IOException occurred while testing if a response was available,"
    168                     + " we will assume one is not.",
    169                     e);
    170                 responseAvailable = false;
    171             }
    172             if (responseAvailable) {
    173                 if (getParams().isParameterTrue(HttpMethodParams.REJECT_HEAD_BODY)) {
    174                     throw new ProtocolException(
    175                         "Body content may not be sent in response to HTTP HEAD request");
    176                 } else {
    177                     LOG.warn("Body content returned in response to HTTP HEAD");
    178                 }
    179                 super.readResponseBody(state, conn);
    180             }
    181         }
    182
    183     }
    184
    185     /**
    186      * Returns non-compliant response body check timeout.
    187      *
    188      * @return The period of time in milliseconds to wait for a response
    189      *         body from a non-compliant server. <tt>-1</tt> returned when
    190      *         non-compliant response body check is disabled
    191      *
    192      * @deprecated Use {@link HttpMethodParams}
    193      *
    194      * @see #getParams()
    195      * @see HttpMethodParams
    196      * @see HttpMethodParams#HEAD_BODY_CHECK_TIMEOUT
    197      */
    198     public int getBodyCheckTimeout() {
    199         return getParams().getIntParameter(HttpMethodParams.HEAD_BODY_CHECK_TIMEOUT, -1);
    200     }
    201
    202     /**
    203      * Sets non-compliant response body check timeout.
    204      *
    205      * @param timeout The period of time in milliseconds to wait for a response
    206      *         body from a non-compliant server. <tt>-1</tt> can be used to
    207      *         disable non-compliant response body check
    208      *
    209      * @deprecated Use {@link HttpMethodParams}
    210      *
    211      * @see #getParams()
    212      * @see HttpMethodParams
    213      * @see HttpMethodParams#HEAD_BODY_CHECK_TIMEOUT
    214      */
    215     public void setBodyCheckTimeout(int timeout) {
    216         getParams().setIntParameter(HttpMethodParams.HEAD_BODY_CHECK_TIMEOUT, timeout);
    217     }
    218
    219 }