blob: d227de531aa72bc7b9e2cb0c222729440cde851d [file] [log] [blame]
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. The ASF licenses this file to You
* under the Apache License, Version 2.0 (the "License"); you may not
* use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License. For additional information regarding
* copyright in this work, please see the NOTICE file in the top level
* directory of this distribution.
*/
package org.apache.roller.weblogger.ui.rendering.util;
import java.text.SimpleDateFormat;
import java.util.Date;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.roller.util.RollerConstants;
import org.apache.roller.util.DateUtil;
import org.apache.roller.weblogger.ui.rendering.mobile.MobileDeviceRepository;
/**
* Utility class to localize the modification date header-related logic.
*/
public final class ModDateHeaderUtil {
private static Log log = LogFactory.getLog(ModDateHeaderUtil.class);
/**
* Instantiates a new mod date header util.
*/
private ModDateHeaderUtil() {
}
/**
* Sets the HTTP response status to 304 (NOT MODIFIED) if the request
* contains an If-Modified-Since header that specifies a time that is at or
* after the time specified by the value of lastModifiedTimeMillis
* <em>truncated to second granularity</em>. Returns true if the response
* status was set, false if not.
*
* @param request
* the request
* @param response
* the response
* @param lastModifiedTimeMillis
* the last modified time millis
* @param deviceType
* the device type. Null to ignore ie no theme device type
* swithing check.
*
* @return true if a response status was sent, false otherwise.
*/
public static boolean respondIfNotModified(HttpServletRequest request,
HttpServletResponse response, long lastModifiedTimeMillis,
MobileDeviceRepository.DeviceType deviceType) {
long sinceDate;
try {
sinceDate = request.getDateHeader("If-Modified-Since");
} catch (IllegalArgumentException ex) {
// this indicates there was some problem parsing the header value as
// a date
return false;
}
// truncate to seconds
lastModifiedTimeMillis -= (lastModifiedTimeMillis % RollerConstants.SEC_IN_MS);
if (log.isDebugEnabled()) {
SimpleDateFormat dateFormat = new SimpleDateFormat(
"EEE MMM dd 'at' h:mm:ss a");
log.debug("since date = "
+ DateUtil.format(new Date(sinceDate), dateFormat));
log.debug("last mod date (trucated to seconds) = "
+ DateUtil.format(new Date(lastModifiedTimeMillis),
dateFormat));
}
// Set device type for device switching
String eTag = null;
if (deviceType != null) {
// int code = new HashCodeBuilder().append(deviceType.name())
// .hashCode();
// eTag = String.valueOf(code);
eTag = deviceType.name();
}
String previousToken = request.getHeader("If-None-Match");
if (eTag != null && previousToken != null && eTag.equals(previousToken)
&& lastModifiedTimeMillis <= sinceDate
|| (eTag == null || previousToken == null)
&& lastModifiedTimeMillis <= sinceDate) {
if (log.isDebugEnabled()) {
log.debug("NOT MODIFIED " + request.getRequestURL());
}
response.setStatus(HttpServletResponse.SC_NOT_MODIFIED);
// use the same date we sent when we created the ETag the
// first time through
response.setHeader("Last-Modified",
request.getHeader("If-Modified-Since"));
return true;
} else {
return false;
}
}
/**
* Set the Last-Modified header using the given time in milliseconds. Note
* that because the header has the granularity of one second, the value will
* get truncated to the nearest second that does not exceed the provided
* value.
* <p/>
* This will also set the Expires header to a date in the past. This forces
* clients to revalidate the cache each time.
*
* @param response
* the response
* @param lastModifiedTimeMillis
* the last modified time millis
* @param deviceType
* the device type. Null to ignore ie no theme device type
* swithing check.
*/
public static void setLastModifiedHeader(HttpServletResponse response,
long lastModifiedTimeMillis,
MobileDeviceRepository.DeviceType deviceType) {
// Save our device type for device switching. Must use chaching on
// headers for this to work.
if (deviceType != null) {
// int code = new HashCodeBuilder().append(deviceType.name())
// .hashCode();
// String eTag = String.valueOf(code);
String eTag = deviceType.name();
response.setHeader("ETag", eTag);
}
response.setDateHeader("Last-Modified", lastModifiedTimeMillis);
// Force clients to revalidate each time
// See RFC 2616 (HTTP 1.1 spec) secs 14.21, 13.2.1
response.setDateHeader("Expires", 0);
// We may also want this (See 13.2.1 and 14.9.4)
// response.setHeader("Cache-Control","must-revalidate");
}
}