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<>(); 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(final FTPFileEntryParser parser) { 086 this(parser, null); 087 } 088 089 /** 090 * Intended for use by FTPClient only 091 * @since 3.4 092 */ 093 FTPListParseEngine(final FTPFileEntryParser parser, final 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(final InputStream stream, final String encoding) 115 throws IOException 116 { 117 this.entries = new LinkedList<>(); 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(final InputStream stream, final String encoding) throws IOException 138 { 139 try (final 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 this.entries.add(line); 146 line = this.parser.readNextEntry(reader); 147 } 148 } 149 } 150 151 /** 152 * Returns an array of at most <code>quantityRequested</code> FTPFile 153 * objects starting at this object's internal iterator's current position. 154 * If fewer than <code>quantityRequested</code> such 155 * elements are available, the returned array will have a length equal 156 * to the number of entries at and after after the current position. 157 * If no such entries are found, this array will have a length of 0. 158 * 159 * After this method is called this object's internal iterator is advanced 160 * by a number of positions equal to the size of the array returned. 161 * 162 * @param quantityRequested 163 * the maximum number of entries we want to get. 164 * 165 * @return an array of at most <code>quantityRequested</code> FTPFile 166 * objects starting at the current position of this iterator within its 167 * list and at least the number of elements which exist in the list at 168 * and after its current position. 169 * <p><b> 170 * NOTE:</b> This array may contain null members if any of the 171 * individual file listings failed to parse. The caller should 172 * check each entry for null before referencing it. 173 */ 174 public FTPFile[] getNext(final int quantityRequested) { 175 final List<FTPFile> tmpResults = new LinkedList<>(); 176 int count = quantityRequested; 177 while (count > 0 && this.internalIterator.hasNext()) { 178 final String entry = this.internalIterator.next(); 179 FTPFile temp = this.parser.parseFTPEntry(entry); 180 if (temp == null && saveUnparseableEntries) { 181 temp = new FTPFile(entry); 182 } 183 tmpResults.add(temp); 184 count--; 185 } 186 return tmpResults.toArray(new FTPFile[tmpResults.size()]); 187 188 } 189 190 /** 191 * Returns an array of at most <code>quantityRequested</code> FTPFile 192 * objects starting at this object's internal iterator's current position, 193 * and working back toward the beginning. 194 * 195 * If fewer than <code>quantityRequested</code> such 196 * elements are available, the returned array will have a length equal 197 * to the number of entries at and after after the current position. 198 * If no such entries are found, this array will have a length of 0. 199 * 200 * After this method is called this object's internal iterator is moved 201 * back by a number of positions equal to the size of the array returned. 202 * 203 * @param quantityRequested 204 * the maximum number of entries we want to get. 205 * 206 * @return an array of at most <code>quantityRequested</code> FTPFile 207 * objects starting at the current position of this iterator within its 208 * list and at least the number of elements which exist in the list at 209 * and after its current position. This array will be in the same order 210 * as the underlying list (not reversed). 211 * <p><b> 212 * NOTE:</b> This array may contain null members if any of the 213 * individual file listings failed to parse. The caller should 214 * check each entry for null before referencing it. 215 */ 216 public FTPFile[] getPrevious(final int quantityRequested) { 217 final List<FTPFile> tmpResults = new LinkedList<>(); 218 int count = quantityRequested; 219 while (count > 0 && this.internalIterator.hasPrevious()) { 220 final String entry = this.internalIterator.previous(); 221 FTPFile temp = this.parser.parseFTPEntry(entry); 222 if (temp == null && saveUnparseableEntries) { 223 temp = new FTPFile(entry); 224 } 225 tmpResults.add(0,temp); 226 count--; 227 } 228 return tmpResults.toArray(new FTPFile[tmpResults.size()]); 229 } 230 231 /** 232 * Returns an array of FTPFile objects containing the whole list of 233 * files returned by the server as read by this object's parser. 234 * 235 * @return an array of FTPFile objects containing the whole list of 236 * files returned by the server as read by this object's parser. 237 * None of the entries will be null 238 * @throws IOException - not ever thrown, may be removed in a later release 239 */ 240 public FTPFile[] getFiles() 241 throws IOException // TODO remove; not actually thrown 242 { 243 return getFiles(FTPFileFilters.NON_NULL); 244 } 245 246 /** 247 * Returns an array of FTPFile objects containing the whole list of 248 * files returned by the server as read by this object's parser. 249 * The files are filtered before being added to the array. 250 * 251 * @param filter FTPFileFilter, must not be <code>null</code>. 252 * 253 * @return an array of FTPFile objects containing the whole list of 254 * files returned by the server as read by this object's parser. 255 * <p><b> 256 * NOTE:</b> This array may contain null members if any of the 257 * individual file listings failed to parse. The caller should 258 * check each entry for null before referencing it, or use the 259 * a filter such as {@link FTPFileFilters#NON_NULL} which does not 260 * allow null entries. 261 * @since 2.2 262 * @throws IOException - not ever thrown, may be removed in a later release 263 */ 264 public FTPFile[] getFiles(final FTPFileFilter filter) 265 throws IOException // TODO remove; not actually thrown 266 { 267 final List<FTPFile> tmpResults = new ArrayList<>(); 268 final Iterator<String> iter = this.entries.iterator(); 269 while (iter.hasNext()) { 270 final String entry = iter.next(); 271 FTPFile temp = this.parser.parseFTPEntry(entry); 272 if (temp == null && saveUnparseableEntries) { 273 temp = new FTPFile(entry); 274 } 275 if (filter.accept(temp)){ 276 tmpResults.add(temp); 277 } 278 } 279 return tmpResults.toArray(new FTPFile[tmpResults.size()]); 280 281 } 282 283 /** 284 * convenience method to allow clients to know whether this object's 285 * internal iterator's current position is at the end of the list. 286 * 287 * @return true if internal iterator is not at end of list, false 288 * otherwise. 289 */ 290 public boolean hasNext() { 291 return internalIterator.hasNext(); 292 } 293 294 /** 295 * convenience method to allow clients to know whether this object's 296 * internal iterator's current position is at the beginning of the list. 297 * 298 * @return true if internal iterator is not at beginning of list, false 299 * otherwise. 300 */ 301 public boolean hasPrevious() { 302 return internalIterator.hasPrevious(); 303 } 304 305 /** 306 * resets this object's internal iterator to the beginning of the list. 307 */ 308 public void resetIterator() { 309 this.internalIterator = this.entries.listIterator(); 310 } 311 312 // DEPRECATED METHODS - for API compatibility only - DO NOT USE 313 314 /** 315 * Do not use. 316 * @param stream the stream from which to read 317 * @throws IOException on error 318 * @deprecated use {@link #readServerList(InputStream, String)} instead 319 */ 320 @Deprecated 321 public void readServerList(final InputStream stream) 322 throws IOException 323 { 324 readServerList(stream, null); 325 } 326 327}