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
020 import java.io.BufferedReader;
021 import java.io.IOException;
022 import java.io.InputStream;
023 import java.io.InputStreamReader;
024 import java.util.ArrayList;
025 import java.util.Iterator;
026 import java.util.LinkedList;
027 import java.util.List;
028 import java.util.ListIterator;
029
030
031 /**
032 * This class handles the entire process of parsing a listing of
033 * file entries from the server.
034 * <p>
035 * This object defines a two-part parsing mechanism.
036 * <p>
037 * The first part is comprised of reading the raw input into an internal
038 * list of strings. Every item in this list corresponds to an actual
039 * file. All extraneous matter emitted by the server will have been
040 * removed by the end of this phase. This is accomplished in conjunction
041 * with the FTPFileEntryParser associated with this engine, by calling
042 * its methods <code>readNextEntry()</code> - which handles the issue of
043 * what delimits one entry from another, usually but not always a line
044 * feed and <code>preParse()</code> - which handles removal of
045 * extraneous matter such as the preliminary lines of a listing, removal
046 * of duplicates on versioning systems, etc.
047 * <p>
048 * The second part is composed of the actual parsing, again in conjunction
049 * with the particular parser used by this engine. This is controlled
050 * by an iterator over the internal list of strings. This may be done
051 * either in block mode, by calling the <code>getNext()</code> and
052 * <code>getPrevious()</code> methods to provide "paged" output of less
053 * than the whole list at one time, or by calling the
054 * <code>getFiles()</code> method to return the entire list.
055 * <p>
056 * Examples:
057 * <p>
058 * Paged access:
059 * <pre>
060 * FTPClient f=FTPClient();
061 * f.connect(server);
062 * f.login(username, password);
063 * FTPListParseEngine engine = f.initiateListParsing(directory);
064 *
065 * while (engine.hasNext()) {
066 * FTPFile[] files = engine.getNext(25); // "page size" you want
067 * //do whatever you want with these files, display them, etc.
068 * //expensive FTPFile objects not created until needed.
069 * }
070 * </pre>
071 * <p>
072 * For unpaged access, simply use FTPClient.listFiles(). That method
073 * uses this class transparently.
074 * @version $Id: FTPListParseEngine.java 1032954 2010-11-09 12:15:10Z sebb $
075 */
076 public class FTPListParseEngine {
077 private List<String> entries = new LinkedList<String>();
078 private ListIterator<String> _internalIterator = entries.listIterator();
079
080 private final FTPFileEntryParser parser;
081
082 public FTPListParseEngine(FTPFileEntryParser parser) {
083 this.parser = parser;
084 }
085
086 /**
087 * handle the initial reading and preparsing of the list returned by
088 * the server. After this method has completed, this object will contain
089 * a list of unparsed entries (Strings) each referring to a unique file
090 * on the server.
091 *
092 * @param stream input stream provided by the server socket.
093 *
094 * @exception IOException
095 * thrown on any failure to read from the sever.
096 */
097 public void readServerList(InputStream stream, String encoding)
098 throws IOException
099 {
100 this.entries = new LinkedList<String>();
101 readStream(stream, encoding);
102 this.parser.preParse(this.entries);
103 resetIterator();
104 }
105
106 /**
107 * handle the iniitial reading and preparsing of the list returned by
108 * the server. After this method has completed, this object will contain
109 * a list of unparsed entries (Strings) each referring to a unique file
110 * on the server.
111 *
112 * @param stream input stream provided by the server socket.
113 *
114 * @exception IOException
115 * thrown on any failure to read from the sever.
116 *
117 * @deprecated The version of this method which takes an encoding should be used.
118 */
119 @Deprecated
120 public void readServerList(InputStream stream)
121 throws IOException
122 {
123 readServerList(stream, null);
124 }
125
126 /**
127 * Internal method for reading the input into the <code>entries</code> list.
128 * After this method has completed, <code>entries</code> will contain a
129 * collection of entries (as defined by
130 * <code>FTPFileEntryParser.readNextEntry()</code>), but this may contain
131 * various non-entry preliminary lines from the server output, duplicates,
132 * and other data that will not be part of the final listing.
133 *
134 * @param stream The socket stream on which the input will be read.
135 * @param encoding The encoding to use.
136 *
137 * @exception IOException
138 * thrown on any failure to read the stream
139 */
140 private void readStream(InputStream stream, String encoding) throws IOException
141 {
142 BufferedReader reader;
143 if (encoding == null)
144 {
145 reader = new BufferedReader(new InputStreamReader(stream));
146 }
147 else
148 {
149 reader = new BufferedReader(new InputStreamReader(stream, encoding));
150 }
151
152 String line = this.parser.readNextEntry(reader);
153
154 while (line != null)
155 {
156 this.entries.add(line);
157 line = this.parser.readNextEntry(reader);
158 }
159 reader.close();
160 }
161
162 /**
163 * Returns an array of at most <code>quantityRequested</code> FTPFile
164 * objects starting at this object's internal iterator's current position.
165 * If fewer than <code>quantityRequested</code> such
166 * elements are available, the returned array will have a length equal
167 * to the number of entries at and after after the current position.
168 * If no such entries are found, this array will have a length of 0.
169 *
170 * After this method is called this object's internal iterator is advanced
171 * by a number of positions equal to the size of the array returned.
172 *
173 * @param quantityRequested
174 * the maximum number of entries we want to get.
175 *
176 * @return an array of at most <code>quantityRequested</code> FTPFile
177 * objects starting at the current position of this iterator within its
178 * list and at least the number of elements which exist in the list at
179 * and after its current position.
180 * <p><b>
181 * NOTE:</b> This array may contain null members if any of the
182 * individual file listings failed to parse. The caller should
183 * check each entry for null before referencing it.
184 */
185 public FTPFile[] getNext(int quantityRequested) {
186 List<FTPFile> tmpResults = new LinkedList<FTPFile>();
187 int count = quantityRequested;
188 while (count > 0 && this._internalIterator.hasNext()) {
189 String entry = this._internalIterator.next();
190 FTPFile temp = this.parser.parseFTPEntry(entry);
191 tmpResults.add(temp);
192 count--;
193 }
194 return tmpResults.toArray(new FTPFile[tmpResults.size()]);
195
196 }
197
198 /**
199 * Returns an array of at most <code>quantityRequested</code> FTPFile
200 * objects starting at this object's internal iterator's current position,
201 * and working back toward the beginning.
202 *
203 * If fewer than <code>quantityRequested</code> such
204 * elements are available, the returned array will have a length equal
205 * to the number of entries at and after after the current position.
206 * If no such entries are found, this array will have a length of 0.
207 *
208 * After this method is called this object's internal iterator is moved
209 * back by a number of positions equal to the size of the array returned.
210 *
211 * @param quantityRequested
212 * the maximum number of entries we want to get.
213 *
214 * @return an array of at most <code>quantityRequested</code> FTPFile
215 * objects starting at the current position of this iterator within its
216 * list and at least the number of elements which exist in the list at
217 * and after its current position. This array will be in the same order
218 * as the underlying list (not reversed).
219 * <p><b>
220 * NOTE:</b> This array may contain null members if any of the
221 * individual file listings failed to parse. The caller should
222 * check each entry for null before referencing it.
223 */
224 public FTPFile[] getPrevious(int quantityRequested) {
225 List<FTPFile> tmpResults = new LinkedList<FTPFile>();
226 int count = quantityRequested;
227 while (count > 0 && this._internalIterator.hasPrevious()) {
228 String entry = this._internalIterator.previous();
229 FTPFile temp = this.parser.parseFTPEntry(entry);
230 tmpResults.add(0,temp);
231 count--;
232 }
233 return tmpResults.toArray(new FTPFile[tmpResults.size()]);
234 }
235
236 /**
237 * Returns an array of FTPFile objects containing the whole list of
238 * files returned by the server as read by this object's parser.
239 *
240 * @return an array of FTPFile objects containing the whole list of
241 * files returned by the server as read by this object's parser.
242 * <p><b>
243 * NOTE:</b> This array may contain null members if any of the
244 * individual file listings failed to parse. The caller should
245 * check each entry for null before referencing it.
246 * @exception IOException
247 */
248 public FTPFile[] getFiles()
249 throws IOException
250 {
251 return getFiles(FTPFileFilters.ALL);
252 }
253
254 /**
255 * Returns an array of FTPFile objects containing the whole list of
256 * files returned by the server as read by this object's parser.
257 * The files are filtered before being added to the array.
258 *
259 * @param filter FTPFileFilter, must not be <code>null</code>.
260 *
261 * @return an array of FTPFile objects containing the whole list of
262 * files returned by the server as read by this object's parser.
263 * <p><b>
264 * NOTE:</b> This array may contain null members if any of the
265 * individual file listings failed to parse. The caller should
266 * check each entry for null before referencing it, or use the
267 * a filter such as {@link FTPFileFilters#NON_NULL} which does not
268 * allow null entries.
269 * @since 2.2
270 * @exception IOException
271 */
272 public FTPFile[] getFiles(FTPFileFilter filter)
273 throws IOException
274 {
275 List<FTPFile> tmpResults = new ArrayList<FTPFile>();
276 Iterator<String> iter = this.entries.iterator();
277 while (iter.hasNext()) {
278 String entry = iter.next();
279 FTPFile temp = this.parser.parseFTPEntry(entry);
280 if (filter.accept(temp)){
281 tmpResults.add(temp);
282 }
283 }
284 return tmpResults.toArray(new FTPFile[tmpResults.size()]);
285
286 }
287
288 /**
289 * convenience method to allow clients to know whether this object's
290 * internal iterator's current position is at the end of the list.
291 *
292 * @return true if internal iterator is not at end of list, false
293 * otherwise.
294 */
295 public boolean hasNext() {
296 return _internalIterator.hasNext();
297 }
298
299 /**
300 * convenience method to allow clients to know whether this object's
301 * internal iterator's current position is at the beginning of the list.
302 *
303 * @return true if internal iterator is not at beginning of list, false
304 * otherwise.
305 */
306 public boolean hasPrevious() {
307 return _internalIterator.hasPrevious();
308 }
309
310 /**
311 * resets this object's internal iterator to the beginning of the list.
312 */
313 public void resetIterator() {
314 this._internalIterator = this.entries.listIterator();
315 }
316 }