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    1   package org.apache.turbine.util;
    2
    3   /*
    4    * Licensed to the Apache Software Foundation (ASF) under one
    5    * or more contributor license agreements.  See the NOTICE file
    6    * distributed with this work for additional information
    7    * regarding copyright ownership.  The ASF licenses this file
    8    * to you under the Apache License, Version 2.0 (the
    9    * "License"); you may not use this file except in compliance
    10   * with the License.  You may obtain a copy of the License at
    11   *
    12   *   http://www.apache.org/licenses/LICENSE-2.0
    13   *
    14   * Unless required by applicable law or agreed to in writing,
    15   * software distributed under the License is distributed on an
    16   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
    17   * KIND, either express or implied.  See the License for the
    18   * specific language governing permissions and limitations
    19   * under the License.
    20   */
    21
    22  import java.util.Date;
    23  import java.util.Locale;
    24  import java.util.TimeZone;
    25
    26  import javax.servlet.http.HttpServletResponse;
    27
    28  import org.apache.commons.lang.time.FastDateFormat;
    29  import org.apache.turbine.Turbine;
    30  import org.apache.turbine.pipeline.PipelineData;
    31
    32  /**
    33   * This class provides utilities for handling some semi-trivial HTTP stuff that
    34   * would otherwise be handled elsewhere.
    35   *
    36   * @author <a href="mailto:magnus@handpoint.com">Magnús Þór Torfason</a>
    37   * @version $Id: HttpUtils.java 1706239 2015-10-01 13:18:35Z tv $
    38   */
    39  public class HttpUtils
    40  {
    41      /**
    42       * The date format to use for HTTP Dates.
    43       */
    44      private static FastDateFormat httpDateFormat = FastDateFormat.getInstance(
    45                  "EEE, dd MMM yyyy HH:mm:ss z",
    46                  TimeZone.getTimeZone("GMT"),
    47                  Locale.US);
    48
    49      /**
    50       * Formats a java Date according to rfc 1123, the rfc standard for dates in
    51       * http.
    52       *
    53       * @param date The Date to format
    54       * @return A String representation of the date
    55       */
    56      public static String formatHttpDate(Date date)
    57      {
    58          return httpDateFormat.format(date);
    59      }
    60
    61      /**
    62       * This method sets the required expiration headers in the response for a
    63       * given {@link PipelineData} object.  This method attempts to set all relevant headers,
    64       * both for HTTP 1.0 and HTTP 1.1.
    65       *
    66       * @param pipelineData The {@link PipelineData} object we are setting cache information for.
    67       * @param expiry The number of milliseconds until the document should expire,
    68       * <code>0</code> indicating immediate expiration (i.e. no caching).
    69       */
    70      public static void setCacheHeaders(PipelineData pipelineData, int expiry)
    71      {
    72          HttpServletResponse response = pipelineData.get(Turbine.class, HttpServletResponse.class);
    73
    74          if (0 == expiry)
    75          {
    76              response.setHeader("Pragma", "no-cache");
    77              response.setHeader("Cache-Control", "no-cache");
    78              response.setDateHeader("Expires", System.currentTimeMillis());
    79          }
    80          else
    81          {
    82              response.setDateHeader("Expires", System.currentTimeMillis() + expiry);
    83          }
    84      }
    85  }