    001    /*
    002     * Licensed to the Apache Software Foundation (ASF) under one or more
    003     * contributor license agreements.  See the NOTICE file distributed with
    004     * this work for additional information regarding copyright ownership.
    005     * The ASF licenses this file to You under the Apache License, Version 2.0
    006     * (the "License"); you may not use this file except in compliance with
    007     * the License.  You may obtain a copy of the License at
    008     *
    009     *      http://www.apache.org/licenses/LICENSE-2.0
    010     *
    011     * Unless required by applicable law or agreed to in writing, software
    012     * distributed under the License is distributed on an "AS IS" BASIS,
    013     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    014     * See the License for the specific language governing permissions and
    015     * limitations under the License.
    016     */
    017
    018    package org.apache.commons.net.ftp;
    019    import java.io.BufferedReader;
    020    import java.io.IOException;
    021    import java.util.List;
    022
    023    /**
    024     * FTPFileEntryParser defines the interface for parsing a single FTP file
    025     * listing and converting that information into an
    026     * {@link org.apache.commons.net.ftp.FTPFile} instance.
    027     * Sometimes you will want to parse unusual listing formats, in which
    028     * case you would create your own implementation of FTPFileEntryParser and
    029     * if necessary, subclass FTPFile.
    030     * <p>
    031     * Here are some examples showing how to use one of the classes that
    032     * implement this interface.
    033     * <p>
    034     * The first example shows how to get an <b>iterable</b> list of files in which the
    035     * more expensive <code>FTPFile</code> objects are not created until needed.  This
    036     * is suitable for paged displays.   It requires that a parser object be created
    037     * beforehand: <code>parser</code> is an object (in the package
    038     * <code>org.apache.commons.net.ftp.parser</code>)
    039     * implementing this inteface.
    040     *
    041     * <pre>
    042     *    FTPClient f=FTPClient();
    043     *    f.connect(server);
    044     *    f.login(username, password);
    045     *    FTPFileList list = f.createFileList(directory, parser);
    046     *    FTPFileIterator iter = list.iterator();
    047     *
    048     *    while (iter.hasNext()) {
    049     *       FTPFile[] files = iter.getNext(25);  // "page size" you want
    050     *       //do whatever you want with these files, display them, etc.
    051     *       //expensive FTPFile objects not created until needed.
    052     *    }
    053     * </pre>
    054     *
    055     * The second example uses the revised <code>FTPClient.listFiles()</code>
    056     * API to pull the whole list from the subfolder <code>subfolder</code> in
    057     * one call, attempting to automatically detect the parser type.  This
    058     * method, without a parserKey parameter, indicates that autodection should
    059     * be used.
    060     *
    061     * <pre>
    062     *    FTPClient f=FTPClient();
    063     *    f.connect(server);
    064     *    f.login(username, password);
    065     *    FTPFile[] files = f.listFiles("subfolder");
    066     * </pre>
    067     *
    068     * The third example uses the revised <code>FTPClient.listFiles()</code>>
    069     * API to pull the whole list from the current working directory in one call,
    070     * but specifying by classname the parser to be used.  For this particular
    071     * parser class, this approach is necessary since there is no way to
    072     * autodetect this server type.
    073     *
    074     * <pre>
    075     *    FTPClient f=FTPClient();
    076     *    f.connect(server);
    077     *    f.login(username, password);
    078     *    FTPFile[] files = f.listFiles(
    079     *      "org.apache.commons.net.ftp.parser.EnterpriseUnixFTPFileEntryParser",
    080     *      ".");
    081     * </pre>
    082     *
    083     * The fourth example uses the revised <code>FTPClient.listFiles()</code>
    084     * API to pull a single file listing in an arbitrary directory in one call,
    085     * specifying by KEY the parser to be used, in this case, VMS.
    086     *
    087     * <pre>
    088     *    FTPClient f=FTPClient();
    089     *    f.connect(server);
    090     *    f.login(username, password);
    091     *    FTPFile[] files = f.listFiles("VMS", "subfolder/foo.java");
    092     * </pre>
    093     *
    094     * @author <a href="mailto:scohen@apache.org">Steve Cohen</a>
    095     * @version $Id: FTPFileEntryParser.java 748376 2009-02-27 01:57:19Z sebb $
    096     * @see org.apache.commons.net.ftp.FTPFile
    097     * @see org.apache.commons.net.ftp.FTPClient#listFiles()
    098     */
    099    public interface FTPFileEntryParser
    100    {
    101        /**
    102         * Parses a line of an FTP server file listing and converts it into a usable
    103         * format in the form of an <code> FTPFile </code> instance.  If the
    104         * file listing line doesn't describe a file, <code> null </code> should be
    105         * returned, otherwise a <code> FTPFile </code> instance representing the
    106         * files in the directory is returned.
    107         * <p>
    108         * @param listEntry A line of text from the file listing
    109         * @return An FTPFile instance corresponding to the supplied entry
    110         */
    111        FTPFile parseFTPEntry(String listEntry);
    112
    113        /**
    114         * Reads the next entry using the supplied BufferedReader object up to
    115         * whatever delemits one entry from the next.  Implementors must define
    116         * this for the particular ftp system being parsed.  In many but not all
    117         * cases, this can be defined simply by calling BufferedReader.readLine().
    118         *
    119         * @param reader The BufferedReader object from which entries are to be
    120         * read.
    121         *
    122         * @return A string representing the next ftp entry or null if none found.
    123         * @exception IOException thrown on any IO Error reading from the reader.
    124         */
    125        String readNextEntry(BufferedReader reader) throws IOException;
    126
    127
    128        /**
    129         * This method is a hook for those implementors (such as
    130         * VMSVersioningFTPEntryParser, and possibly others) which need to
    131         * perform some action upon the FTPFileList after it has been created
    132         * from the server stream, but before any clients see the list.
    133         *
    134         * The default implementation can be a no-op.
    135         *
    136         * @param original Original list after it has been created from the server stream
    137         *
    138         * @return Original list as processed by this method.
    139         */
    140        List<String> preParse(List<String> original);
    141
    142
    143    }
    144
    145
    146    /* Emacs configuration
    147     * Local variables:        **
    148     * mode:             java  **
    149     * c-basic-offset:   4     **
    150     * indent-tabs-mode: nil   **
    151     * End:                    **
    152     */