    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
    018package org.apache.commons.net.ftp;
    019
    020import java.io.BufferedReader;
    021import java.io.IOException;
    022import java.io.InputStream;
    023import java.io.InputStreamReader;
    024import java.util.ArrayList;
    025import java.util.Iterator;
    026import java.util.LinkedList;
    027import java.util.List;
    028import java.util.ListIterator;
    029
    030import org.apache.commons.net.util.Charsets;
    031
    032
    033/**
    034 * This class handles the entire process of parsing a listing of
    035 * file entries from the server.
    036 * <p>
    037 * This object defines a two-part parsing mechanism.
    038 * <p>
    039 * The first part is comprised of reading the raw input into an internal
    040 * list of strings.  Every item in this list corresponds to an actual
    041 * file.  All extraneous matter emitted by the server will have been
    042 * removed by the end of this phase.  This is accomplished in conjunction
    043 * with the FTPFileEntryParser associated with this engine, by calling
    044 * its methods <code>readNextEntry()</code> - which handles the issue of
    045 * what delimits one entry from another, usually but not always a line
    046 * feed and <code>preParse()</code> - which handles removal of
    047 * extraneous matter such as the preliminary lines of a listing, removal
    048 * of duplicates on versioning systems, etc.
    049 * <p>
    050 * The second part is composed of the actual parsing, again in conjunction
    051 * with the particular parser used by this engine.  This is controlled
    052 * by an iterator over the internal list of strings.  This may be done
    053 * either in block mode, by calling the <code>getNext()</code> and
    054 * <code>getPrevious()</code> methods to provide "paged" output of less
    055 * than the whole list at one time, or by calling the
    056 * <code>getFiles()</code> method to return the entire list.
    057 * <p>
    058 * Examples:
    059 * <p>
    060 * Paged access:
    061 * <pre>
    062 *    FTPClient f=FTPClient();
    063 *    f.connect(server);
    064 *    f.login(username, password);
    065 *    FTPListParseEngine engine = f.initiateListParsing(directory);
    066 *
    067 *    while (engine.hasNext()) {
    068 *       FTPFile[] files = engine.getNext(25);  // "page size" you want
    069 *       //do whatever you want with these files, display them, etc.
    070 *       //expensive FTPFile objects not created until needed.
    071 *    }
    072 * </pre>
    073 * <p>
    074 * For unpaged access, simply use FTPClient.listFiles().  That method
    075 * uses this class transparently.
    076 */
    077public class FTPListParseEngine {
    078    private List<String> entries = new LinkedList<String>();
    079    private ListIterator<String> _internalIterator = entries.listIterator();
    080
    081    private final FTPFileEntryParser parser;
    082    // Should invalid files (parse failures) be allowed?
    083    private final boolean saveUnparseableEntries;
    084
    085    public FTPListParseEngine(FTPFileEntryParser parser) {
    086        this(parser, null);
    087    }
    088
    089    /**
    090     * Intended for use by FTPClient only
    091     * @since 3.4
    092     */
    093    FTPListParseEngine(FTPFileEntryParser parser, FTPClientConfig configuration) {
    094        this.parser = parser;
    095        if (configuration != null) {
    096            this.saveUnparseableEntries = configuration.getUnparseableEntries();
    097        } else {
    098            this.saveUnparseableEntries = false;
    099        }
    100    }
    101
    102    /**
    103     * handle the initial reading and preparsing of the list returned by
    104     * the server.  After this method has completed, this object will contain
    105     * a list of unparsed entries (Strings) each referring to a unique file
    106     * on the server.
    107     *
    108     * @param stream input stream provided by the server socket.
    109     * @param encoding the encoding to be used for reading the stream
    110     *
    111     * @throws IOException
    112     *                   thrown on any failure to read from the sever.
    113     */
    114    public void readServerList(InputStream stream, String encoding)
    115    throws IOException
    116    {
    117        this.entries = new LinkedList<String>();
    118        readStream(stream, encoding);
    119        this.parser.preParse(this.entries);
    120        resetIterator();
    121    }
    122
    123    /**
    124     * Internal method for reading the input into the <code>entries</code> list.
    125     * After this method has completed, <code>entries</code> will contain a
    126     * collection of entries (as defined by
    127     * <code>FTPFileEntryParser.readNextEntry()</code>), but this may contain
    128     * various non-entry preliminary lines from the server output, duplicates,
    129     * and other data that will not be part of the final listing.
    130     *
    131     * @param stream The socket stream on which the input will be read.
    132     * @param encoding The encoding to use.
    133     *
    134     * @throws IOException
    135     *                   thrown on any failure to read the stream
    136     */
    137    private void readStream(InputStream stream, String encoding) throws IOException
    138    {
    139        BufferedReader reader = new BufferedReader(
    140                new InputStreamReader(stream, Charsets.toCharset(encoding)));
    141
    142        String line = this.parser.readNextEntry(reader);
    143
    144        while (line != null)
    145        {
    146            this.entries.add(line);
    147            line = this.parser.readNextEntry(reader);
    148        }
    149        reader.close();
    150    }
    151
    152    /**
    153     * Returns an array of at most <code>quantityRequested</code> FTPFile
    154     * objects starting at this object's internal iterator's current position.
    155     * If fewer than <code>quantityRequested</code> such
    156     * elements are available, the returned array will have a length equal
    157     * to the number of entries at and after after the current position.
    158     * If no such entries are found, this array will have a length of 0.
    159     *
    160     * After this method is called this object's internal iterator is advanced
    161     * by a number of positions equal to the size of the array returned.
    162     *
    163     * @param quantityRequested
    164     * the maximum number of entries we want to get.
    165     *
    166     * @return an array of at most <code>quantityRequested</code> FTPFile
    167     * objects starting at the current position of this iterator within its
    168     * list and at least the number of elements which  exist in the list at
    169     * and after its current position.
    170     * <p><b>
    171     * NOTE:</b> This array may contain null members if any of the
    172     * individual file listings failed to parse.  The caller should
    173     * check each entry for null before referencing it.
    174     */
    175    public FTPFile[] getNext(int quantityRequested) {
    176        List<FTPFile> tmpResults = new LinkedList<FTPFile>();
    177        int count = quantityRequested;
    178        while (count > 0 && this._internalIterator.hasNext()) {
    179            String entry = this._internalIterator.next();
    180            FTPFile temp = this.parser.parseFTPEntry(entry);
    181            if (temp == null && saveUnparseableEntries) {
    182                temp = new FTPFile(entry);
    183            }
    184            tmpResults.add(temp);
    185            count--;
    186        }
    187        return tmpResults.toArray(new FTPFile[tmpResults.size()]);
    188
    189    }
    190
    191    /**
    192     * Returns an array of at most <code>quantityRequested</code> FTPFile
    193     * objects starting at this object's internal iterator's current position,
    194     * and working back toward the beginning.
    195     *
    196     * If fewer than <code>quantityRequested</code> such
    197     * elements are available, the returned array will have a length equal
    198     * to the number of entries at and after after the current position.
    199     * If no such entries are found, this array will have a length of 0.
    200     *
    201     * After this method is called this object's internal iterator is moved
    202     * back by a number of positions equal to the size of the array returned.
    203     *
    204     * @param quantityRequested
    205     * the maximum number of entries we want to get.
    206     *
    207     * @return an array of at most <code>quantityRequested</code> FTPFile
    208     * objects starting at the current position of this iterator within its
    209     * list and at least the number of elements which  exist in the list at
    210     * and after its current position.  This array will be in the same order
    211     * as the underlying list (not reversed).
    212     * <p><b>
    213     * NOTE:</b> This array may contain null members if any of the
    214     * individual file listings failed to parse.  The caller should
    215     * check each entry for null before referencing it.
    216     */
    217    public FTPFile[] getPrevious(int quantityRequested) {
    218        List<FTPFile> tmpResults = new LinkedList<FTPFile>();
    219        int count = quantityRequested;
    220        while (count > 0 && this._internalIterator.hasPrevious()) {
    221            String entry = this._internalIterator.previous();
    222            FTPFile temp = this.parser.parseFTPEntry(entry);
    223            if (temp == null && saveUnparseableEntries) {
    224                temp = new FTPFile(entry);
    225            }
    226            tmpResults.add(0,temp);
    227            count--;
    228        }
    229        return tmpResults.toArray(new FTPFile[tmpResults.size()]);
    230    }
    231
    232    /**
    233     * Returns an array of FTPFile objects containing the whole list of
    234     * files returned by the server as read by this object's parser.
    235     *
    236     * @return an array of FTPFile objects containing the whole list of
    237     *         files returned by the server as read by this object's parser.
    238     * None of the entries will be null
    239     * @throws IOException - not ever thrown, may be removed in a later release
    240     */
    241    public FTPFile[] getFiles()
    242    throws IOException // TODO remove; not actually thrown
    243    {
    244        return getFiles(FTPFileFilters.NON_NULL);
    245    }
    246
    247    /**
    248     * Returns an array of FTPFile objects containing the whole list of
    249     * files returned by the server as read by this object's parser.
    250     * The files are filtered before being added to the array.
    251     *
    252     * @param filter FTPFileFilter, must not be <code>null</code>.
    253     *
    254     * @return an array of FTPFile objects containing the whole list of
    255     *         files returned by the server as read by this object's parser.
    256     * <p><b>
    257     * NOTE:</b> This array may contain null members if any of the
    258     * individual file listings failed to parse.  The caller should
    259     * check each entry for null before referencing it, or use the
    260     * a filter such as {@link FTPFileFilters#NON_NULL} which does not
    261     * allow null entries.
    262     * @since 2.2
    263     * @throws IOException - not ever thrown, may be removed in a later release
    264     */
    265    public FTPFile[] getFiles(FTPFileFilter filter)
    266    throws IOException // TODO remove; not actually thrown
    267    {
    268        List<FTPFile> tmpResults = new ArrayList<FTPFile>();
    269        Iterator<String> iter = this.entries.iterator();
    270        while (iter.hasNext()) {
    271            String entry = iter.next();
    272            FTPFile temp = this.parser.parseFTPEntry(entry);
    273            if (temp == null && saveUnparseableEntries) {
    274                temp = new FTPFile(entry);
    275            }
    276            if (filter.accept(temp)){
    277                tmpResults.add(temp);
    278            }
    279        }
    280        return tmpResults.toArray(new FTPFile[tmpResults.size()]);
    281
    282    }
    283
    284    /**
    285     * convenience method to allow clients to know whether this object's
    286     * internal iterator's current position is at the end of the list.
    287     *
    288     * @return true if internal iterator is not at end of list, false
    289     * otherwise.
    290     */
    291    public boolean hasNext() {
    292        return _internalIterator.hasNext();
    293    }
    294
    295    /**
    296     * convenience method to allow clients to know whether this object's
    297     * internal iterator's current position is at the beginning of the list.
    298     *
    299     * @return true if internal iterator is not at beginning of list, false
    300     * otherwise.
    301     */
    302    public boolean hasPrevious() {
    303        return _internalIterator.hasPrevious();
    304    }
    305
    306    /**
    307     * resets this object's internal iterator to the beginning of the list.
    308     */
    309    public void resetIterator() {
    310        this._internalIterator = this.entries.listIterator();
    311    }
    312
    313    // DEPRECATED METHODS - for API compatibility only - DO NOT USE
    314
    315    /**
    316     * Do not use.
    317     * @param stream the stream from which to read
    318     * @throws IOException on error
    319     * @deprecated use {@link #readServerList(InputStream, String)} instead
    320    */
    321    @Deprecated
    322    public void readServerList(InputStream stream)
    323    throws IOException
    324    {
    325        readServerList(stream, null);
    326    }
    327
    328}