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03d130e99c
- undeleted and reinstated use of org.alfresco.util.Pair - undeleted org.alfresco.util.PropertyCheck which is used in the deployment code. - undeleted other org.alfresco.util.* classes which probably should never have been moved to spring surf. git-svn-id: https://svn.alfresco.com/repos/alfresco-enterprise/alfresco/HEAD/root@19312 c4b6b30b-aa2e-2d43-bbcb-ca4b014f7261
115 lines
4.3 KiB
Java
115 lines
4.3 KiB
Java
/*
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* Copyright (C) 2005-2010 Alfresco Software Limited.
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*
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* This file is part of Alfresco
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*
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* Alfresco is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Lesser General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* Alfresco is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public License
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* along with Alfresco. If not, see <http://www.gnu.org/licenses/>. */
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package org.alfresco.repo.domain;
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import java.io.UnsupportedEncodingException;
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import java.util.zip.CRC32;
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import org.alfresco.util.Pair;
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/**
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* Helper class to calculate CRC values for string persistence.
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*
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* @author Derek Hulley
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* @since 3.2
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*/
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public class CrcHelper
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{
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public static final String EMPTY_STRING = ".empty";
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/**
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* Calculate a persistable, unique pair of values that can be persisted in a database unique
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* key and guarantee correct case-sensitivity.
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* <p>
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* While the short-string version of the value is always lowercase, the CRC is
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* calculated from the virgin string if case-sensitivity is enforced; in the case-insensitive
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* case, the CRC is calculated from a lowercase version of the string.
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* <p>
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* If the value is an empty string, then {@link #EMPTY_STRING} is used instead. This ensures
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* that persisted values don't fall foul of the Oracle empty string comparison "behaviour" i.e
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* you should never persist an empty string in Oracle as it equates to a SQL <b>NULL</b>.
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*
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* @param value the raw value that will be persisted
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* @param dataLength the maximum number of characters that can be persisted
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* @param useCharsFromStart <tt>true</tt> if the shortened string value must be made from
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* the first characters of the string or <tt>false</tt> to use
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* characters from the end of the string.
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* @param caseSensitive <tt>true</tt> if the resulting pair must be case-sensitive or
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* <tt>false</tt> if the pair must be case-insensitive.
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* @return Return the persistable pair. The result will never be <tt>null</tt>,
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* but the individual pair values will be <tt>null</tt> if the
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* value given is <tt>null</tt>
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*/
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public static Pair<String, Long> getStringCrcPair(
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String value,
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int dataLength,
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boolean useCharsFromStart,
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boolean caseSensitive)
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{
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String valueLowerCase;
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if (value == null)
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{
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return new Pair<String, Long>(null, null);
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}
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else if (value.length() == 0)
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{
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value = CrcHelper.EMPTY_STRING;
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valueLowerCase = value;
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}
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else
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{
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valueLowerCase = value.toLowerCase();
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}
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Long valueCrc;
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try
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{
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CRC32 crc = new CRC32();
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if (caseSensitive)
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{
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crc.update(value.getBytes("UTF-8"));
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}
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else
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{
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crc.update(valueLowerCase.getBytes("UTF-8"));
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}
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valueCrc = crc.getValue();
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}
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catch (UnsupportedEncodingException e)
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{
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throw new RuntimeException("UTF-8 encoding is not supported");
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}
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// Get the short value (case-sensitive or not)
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String valueShort = null;
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int valueLen = valueLowerCase.length();
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if (valueLen < dataLength)
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{
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valueShort = valueLowerCase;
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}
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else if (useCharsFromStart)
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{
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valueShort = valueLowerCase.substring(0, dataLength - 1);
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}
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else
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{
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valueShort = valueLowerCase.substring(valueLen - dataLength);
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}
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return new Pair<String, Long>(valueShort, valueCrc);
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}
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}
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