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Commons Net example source code file (RegexFTPFileEntryParserImpl.java)

This example Commons Net source code file (RegexFTPFileEntryParserImpl.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

ftpfileentryparserimpl, ftpfileentryparserimpl, illegalargumentexception, matcher, matchresult, pattern, patternsyntaxexception, regex, regexftpfileentryparserimpl, regexftpfileentryparserimpl, string, string, stringbuilder, stringbuilder, unparseable

The Commons Net RegexFTPFileEntryParserImpl.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.regex.MatchResult;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import java.util.regex.PatternSyntaxException;

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

/**
 * This abstract class implements both the older FTPFileListParser and
 * newer FTPFileEntryParser interfaces with default functionality.
 * All the classes in the parser subpackage inherit from this.
 *
 * This is the base class for all regular expression based FTPFileEntryParser classes
 *
 * @author Steve Cohen <scohen@apache.org>
 */
public abstract class RegexFTPFileEntryParserImpl extends
        FTPFileEntryParserImpl {
    /**
     * internal pattern the matcher tries to match, representing a file
     * entry
     */
    private Pattern pattern = null;

    /**
     * internal match result used by the parser
     */
    private MatchResult result = null;

    /**
     * Internal PatternMatcher object used by the parser.  It has protected
     * scope in case subclasses want to make use of it for their own purposes.
     */
    protected Matcher _matcher_ = null;

    /**
     * The constructor for a RegexFTPFileEntryParserImpl object.
     *
     * @param regex  The regular expression with which this object is
     * initialized.
     *
     * @exception IllegalArgumentException
     * Thrown if the regular expression is unparseable.  Should not be seen in
     * normal conditions.  It it is seen, this is a sign that a subclass has
     * been created with a bad regular expression.   Since the parser must be
     * created before use, this means that any bad parser subclasses created
     * from this will bomb very quickly,  leading to easy detection.
     */

    public RegexFTPFileEntryParserImpl(String regex) {
        super();
        setRegex(regex);
    }

    /**
     * Convenience method delegates to the internal MatchResult's matches()
     * method.
     *
     * @param s the String to be matched
     * @return true if s matches this object's regular expression.
     */

    public boolean matches(String s) {
        this.result = null;
        _matcher_ = pattern.matcher(s);
        if (_matcher_.matches()) {
            this.result = _matcher_.toMatchResult();
        }
        return null != this.result;
    }

    /**
     * Convenience method
     *
     * @return the number of groups() in the internal MatchResult.
     */

    public int getGroupCnt() {
        if (this.result == null) {
            return 0;
        }
        return this.result.groupCount();
    }

    /**
     * Convenience method delegates to the internal MatchResult's group()
     * method.
     *
     * @param matchnum match group number to be retrieved
     *
     * @return the content of the <code>matchnum'th group of the internal
     *         match or null if this method is called without a match having
     *         been made.
     */
    public String group(int matchnum) {
        if (this.result == null) {
            return null;
        }
        return this.result.group(matchnum);
    }

    /**
     * For debugging purposes - returns a string shows each match group by
     * number.
     *
     * @return a string shows each match group by number.
     */

    public String getGroupsAsString() {
        StringBuilder b = new StringBuilder();
        for (int i = 1; i <= this.result.groupCount(); i++) {
            b.append(i).append(") ").append(this.result.group(i)).append(
                    System.getProperty("line.separator"));
        }
        return b.toString();
    }

    /**
     * Alter the current regular expression being utilised for entry parsing
     * and create a new {@link Pattern} instance.
     * @param regex The new regular expression
     * @return  true if the compiled pattern is not null
     * @since 2.0
     */
    public boolean setRegex(String regex) {
        try {
            pattern = Pattern.compile(regex);
        } catch (PatternSyntaxException pse) {
            throw new IllegalArgumentException("Unparseable regex supplied: "
                    + regex);
        }
        return (pattern != null);
    }

}

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