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 }