/*
* Copyright 2014 cruxframework.org.
*
* Licensed 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.
*/
package org.cruxframework.crux.core.server.rest.state;
import org.apache.commons.lang.StringUtils;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.cruxframework.crux.core.server.rest.spi.UriInfo;
import org.cruxframework.crux.core.server.rest.util.Crc32c;
/**
* Generate a default eTag based in the content.
*
* @author @author Thiago da Rosa de Bustamante
*/
public class ETagHandlerImpl implements ETagHandler
{
private static final Log logger = LogFactory.getLog(ETagHandlerImpl.class);
@Override
public String generateEtag(UriInfo uri, String content)
{
if (StringUtils.isEmpty(content))
{
return null;
}
try
{
Crc32c hash = new Crc32c();
byte[] bytes = content.getBytes("UTF-8");
hash.update(bytes, 0, bytes.length);
String hexString = Long.toHexString(hash.getValue());
return hexString;
}
catch (Exception e)
{
logger.error("Error generating etag with CRC32c algorithm. Ignoring Etag for this resource ["+uri.getPath()+"]...", e);
}
return null;
}
}