org.alfresco.repo.domain

Class CrcHelper

java.lang.Object

org.alfresco.repo.domain.CrcHelper

public class CrcHelper
extends Object

Helper class to calculate CRC values for string persistence.

Since:

3.2

Author:

Derek Hulley

Field Summary

Fields

Modifier and Type	Field and Description
static String	EMPTY_STRING

Constructor Summary

Constructors

Constructor and Description
CrcHelper()

Method Summary

Modifier and Type	Method and Description
static org.alfresco.util.Pair<String,Long>	getStringCrcPair(String value, int dataLength, boolean useCharsFromStart, boolean caseSensitive) Calculate a persistable, unique pair of values that can be persisted in a database unique key and guarantee correct case-sensitivity.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

EMPTY_STRING

public static final String EMPTY_STRING

See Also:

Constant Field Values

Constructor Detail

CrcHelper

public CrcHelper()

Method Detail

getStringCrcPair

public static org.alfresco.util.Pair<String,Long> getStringCrcPair(String value,
                                                                   int dataLength,
                                                                   boolean useCharsFromStart,
                                                                   boolean caseSensitive)

Calculate a persistable, unique pair of values that can be persisted in a database unique key and guarantee correct case-sensitivity.

While the short-string version of the value is always lowercase, the CRC is calculated from the virgin string if case-sensitivity is enforced; in the case-insensitive case, the CRC is calculated from a lowercase version of the string.

If the value is an empty string, then EMPTY_STRING is used instead. This ensures that persisted values don't fall foul of the Oracle empty string comparison "behaviour" i.e you should never persist an empty string in Oracle as it equates to a SQL NULL.

Parameters:

value - the raw value that will be persisted

dataLength - the maximum number of characters that can be persisted

useCharsFromStart - true if the shortened string value must be made from the first characters of the string or false to use characters from the end of the string.

caseSensitive - true if the resulting pair must be case-sensitive or false if the pair must be case-insensitive.

Returns:

Return the persistable pair. The result will never be null, but the individual pair values will be null if the value given is null