Commons Net example source code file (VMSVersioningFTPEntryParser.java)

This example Commons Net source code file (VMSVersioningFTPEntryParser.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Commons Net tags/keywords

hashmap, integer, integer, matcher, matchresult, override, patternsyntaxexception, pre_parse_regex, pre_parse_regex, regex, string, string, unparseable, util, vmsversioningftpentryparser, vmsversioningftpentryparser

The Commons Net VMSVersioningFTPEntryParser.java source code

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * 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.
 */

package org.apache.commons.net.ftp.parser;

import java.util.HashMap;
import java.util.List;
import java.util.ListIterator;
import java.util.regex.MatchResult;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import java.util.regex.PatternSyntaxException;

import org.apache.commons.net.ftp.FTPClientConfig;

/**
 * Special implementation VMSFTPEntryParser with versioning turned on.
 * This parser removes all duplicates and only leaves the version with the highest
 * version number for each filename.
 *
 * This is a sample of VMS LIST output
 *
 *  "1-JUN.LIS;1              9/9           2-JUN-1998 07:32:04  [GROUP,OWNER]    (RWED,RWED,RWED,RE)",
 *  "1-JUN.LIS;2              9/9           2-JUN-1998 07:32:04  [GROUP,OWNER]    (RWED,RWED,RWED,RE)",
 *  "DATA.DIR;1               1/9           2-JUN-1998 07:32:04  [GROUP,OWNER]    (RWED,RWED,RWED,RE)",
 * <P>
 *
 * @author  <a href="Winston.Ojeda@qg.com">Winston Ojeda
 * @author <a href="sestegra@free.fr">Stephane ESTE-GRACIAS
 * @version $Id: VMSVersioningFTPEntryParser.java 1084380 2011-03-22 22:23:35Z sebb $
 *
 * @see org.apache.commons.net.ftp.FTPFileEntryParser FTPFileEntryParser (for usage instructions)
 */
public class VMSVersioningFTPEntryParser extends VMSFTPEntryParser
{

    private final Pattern _preparse_pattern_;
    private static final String PRE_PARSE_REGEX =
        "(.*);([0-9]+)\\s*.*";

    /**
     * Constructor for a VMSFTPEntryParser object.
     *
     * @exception IllegalArgumentException
     * Thrown if the regular expression is unparseable.  Should not be seen
     * under normal conditions.  It it is seen, this is a sign that
     * <code>REGEX is  not a valid regular expression.
     */
    public VMSVersioningFTPEntryParser()
    {
        this(null);
    }

    /**
     * This constructor allows the creation of a VMSVersioningFTPEntryParser
     * object with something other than the default configuration.
     *
     * @param config The {@link FTPClientConfig configuration} object used to
     * configure this parser.
     * @exception IllegalArgumentException
     * Thrown if the regular expression is unparseable.  Should not be seen
     * under normal conditions.  It it is seen, this is a sign that
     * <code>REGEX is  not a valid regular expression.
     * @since 1.4
     */
    public VMSVersioningFTPEntryParser(FTPClientConfig config)
    {
        super();
        configure(config);
        try
        {
            //_preparse_matcher_ = new Perl5Matcher();
            _preparse_pattern_ = Pattern.compile(PRE_PARSE_REGEX);
        }
        catch (PatternSyntaxException pse)
        {
            throw new IllegalArgumentException (
                "Unparseable regex supplied:  " + PRE_PARSE_REGEX);
        }

   }

    /**
     * Implement hook provided for those implementers (such as
     * VMSVersioningFTPEntryParser, and possibly others) which return
     * multiple files with the same name to remove the duplicates ..
     *
     * @param original Original list
     *
     * @return Original list purged of duplicates
     */
    @Override
    public List<String> preParse(List original) {
        HashMap<String, Integer> existingEntries = new HashMap();
        ListIterator<String> iter = original.listIterator();
        while (iter.hasNext()) {
            String entry = iter.next().trim();
            MatchResult result = null;
            Matcher _preparse_matcher_ = _preparse_pattern_.matcher(entry);
            if (_preparse_matcher_.matches()) {
                result = _preparse_matcher_.toMatchResult();
                String name = result.group(1);
                String version = result.group(2);
                Integer nv = Integer.valueOf(version);
                Integer existing = existingEntries.get(name);
                if (null != existing) {
                    if (nv.intValue() < existing.intValue()) {
                        iter.remove();  // removes older version from original list.
                        continue;
                    }
                }
                existingEntries.put(name, nv);
            }

        }
        // we've now removed all entries less than with less than the largest
        // version number for each name that were listed after the largest.
        // we now must remove those with smaller than the largest version number
        // for each name that were found before the largest
        while (iter.hasPrevious()) {
            String entry = iter.previous().trim();
            MatchResult result = null;
            Matcher _preparse_matcher_ = _preparse_pattern_.matcher(entry);
            if (_preparse_matcher_.matches()) {
                result = _preparse_matcher_.toMatchResult();
                String name = result.group(1);
                String version = result.group(2);
                Integer nv = Integer.valueOf(version);
                Integer existing = existingEntries.get(name);
                if (null != existing) {
                    if (nv.intValue() < existing.intValue()) {
                        iter.remove(); // removes older version from original list.
                    }
                }
            }

        }
        return original;
    }


    @Override
    protected boolean isVersioning() {
        return true;
    }

}

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