/** * Licensed under the Artistic License; you may not use this file * except in compliance with the License. * You may obtain a copy of the License at * *      http://displaytag.sourceforge.net/license.html * * THIS PACKAGE IS PROVIDED "AS IS" AND WITHOUT ANY EXPRESS OR * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE. */package org.displaytag.util;import java.io.Serializable;/** * Simple utility class for encoding parameter names. * @author Fabrizio Giustina * @version $Revision: 1081 $ ($Author: fgiust $) */public class ParamEncoder implements Serializable{    /**     * D1597A17A6.     */    private static final long serialVersionUID = 899149338534L;    /**     * Unique identifier for a tag with the given id/name.     */    private String parameterIdentifier;    /**     * Generates a new parameter encoder for the table with the given id.     * @param idAttribute value of "id" attribute     */    public ParamEncoder(String idAttribute)    {        // use name and id to get the unique identifier        String stringIdentifier = "x-" + idAttribute; //$NON-NLS-1$        // get the array        char[] charArray = stringIdentifier.toCharArray();        // calculate a simple checksum-like value        int checkSum = 17;        for (int j = 0; j < charArray.length; j++)        {            checkSum = 3 * checkSum + charArray[j];        }        // keep it positive        checkSum &= 0x7fffff;        // this is the full identifier used for all the parameters        this.parameterIdentifier = "d-" + checkSum + "-"; //$NON-NLS-1$ //$NON-NLS-2$    }    /**     * encode a parameter name prepending calculated <code>parameterIdentifier</code>.     * @param paramName parameter name     * @return encoded parameter name in the form <code>d-<em>XXXX</em>-<em>name</em></code>     */    public String encodeParameterName(String paramName)    {        return this.parameterIdentifier + paramName;    }    /**     * Check if the given parameter has been encoded using paramEncoder. It actually check if the parameter name starts     * with the calculated <code>parameterIdentifier</code>. Null safe (a null string returns <code>false</code>).     * @param paramName parameter name     * @return <code>true</code> if the given parameter as been encoded using this param encoder     */    public boolean isParameterEncoded(String paramName)    {        return paramName != null && paramName.startsWith(this.parameterIdentifier);    }}