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 1085209 2011-03-25 00:08:04Z 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 * Internal method for reading the input into the <code>entries</code> list. 108 * After this method has completed, <code>entries</code> will contain a 109 * collection of entries (as defined by 110 * <code>FTPFileEntryParser.readNextEntry()</code>), but this may contain 111 * various non-entry preliminary lines from the server output, duplicates, 112 * and other data that will not be part of the final listing. 113 * 114 * @param stream The socket stream on which the input will be read. 115 * @param encoding The encoding to use. 116 * 117 * @exception IOException 118 * thrown on any failure to read the stream 119 */ 120 private void readStream(InputStream stream, String encoding) throws IOException 121 { 122 BufferedReader reader; 123 if (encoding == null) 124 { 125 reader = new BufferedReader(new InputStreamReader(stream)); 126 } 127 else 128 { 129 reader = new BufferedReader(new InputStreamReader(stream, encoding)); 130 } 131 132 String line = this.parser.readNextEntry(reader); 133 134 while (line != null) 135 { 136 this.entries.add(line); 137 line = this.parser.readNextEntry(reader); 138 } 139 reader.close(); 140 } 141 142 /** 143 * Returns an array of at most <code>quantityRequested</code> FTPFile 144 * objects starting at this object's internal iterator's current position. 145 * If fewer than <code>quantityRequested</code> such 146 * elements are available, the returned array will have a length equal 147 * to the number of entries at and after after the current position. 148 * If no such entries are found, this array will have a length of 0. 149 * 150 * After this method is called this object's internal iterator is advanced 151 * by a number of positions equal to the size of the array returned. 152 * 153 * @param quantityRequested 154 * the maximum number of entries we want to get. 155 * 156 * @return an array of at most <code>quantityRequested</code> FTPFile 157 * objects starting at the current position of this iterator within its 158 * list and at least the number of elements which exist in the list at 159 * and after its current position. 160 * <p><b> 161 * NOTE:</b> This array may contain null members if any of the 162 * individual file listings failed to parse. The caller should 163 * check each entry for null before referencing it. 164 */ 165 public FTPFile[] getNext(int quantityRequested) { 166 List<FTPFile> tmpResults = new LinkedList<FTPFile>(); 167 int count = quantityRequested; 168 while (count > 0 && this._internalIterator.hasNext()) { 169 String entry = this._internalIterator.next(); 170 FTPFile temp = this.parser.parseFTPEntry(entry); 171 tmpResults.add(temp); 172 count--; 173 } 174 return tmpResults.toArray(new FTPFile[tmpResults.size()]); 175 176 } 177 178 /** 179 * Returns an array of at most <code>quantityRequested</code> FTPFile 180 * objects starting at this object's internal iterator's current position, 181 * and working back toward the beginning. 182 * 183 * If fewer than <code>quantityRequested</code> such 184 * elements are available, the returned array will have a length equal 185 * to the number of entries at and after after the current position. 186 * If no such entries are found, this array will have a length of 0. 187 * 188 * After this method is called this object's internal iterator is moved 189 * back by a number of positions equal to the size of the array returned. 190 * 191 * @param quantityRequested 192 * the maximum number of entries we want to get. 193 * 194 * @return an array of at most <code>quantityRequested</code> FTPFile 195 * objects starting at the current position of this iterator within its 196 * list and at least the number of elements which exist in the list at 197 * and after its current position. This array will be in the same order 198 * as the underlying list (not reversed). 199 * <p><b> 200 * NOTE:</b> This array may contain null members if any of the 201 * individual file listings failed to parse. The caller should 202 * check each entry for null before referencing it. 203 */ 204 public FTPFile[] getPrevious(int quantityRequested) { 205 List<FTPFile> tmpResults = new LinkedList<FTPFile>(); 206 int count = quantityRequested; 207 while (count > 0 && this._internalIterator.hasPrevious()) { 208 String entry = this._internalIterator.previous(); 209 FTPFile temp = this.parser.parseFTPEntry(entry); 210 tmpResults.add(0,temp); 211 count--; 212 } 213 return tmpResults.toArray(new FTPFile[tmpResults.size()]); 214 } 215 216 /** 217 * Returns an array of FTPFile objects containing the whole list of 218 * files returned by the server as read by this object's parser. 219 * 220 * @return an array of FTPFile objects containing the whole list of 221 * files returned by the server as read by this object's parser. 222 * None of the entries will be null 223 * @exception IOException 224 */ 225 public FTPFile[] getFiles() 226 throws IOException 227 { 228 return getFiles(FTPFileFilters.NON_NULL); 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 * The files are filtered before being added to the array. 235 * 236 * @param filter FTPFileFilter, must not be <code>null</code>. 237 * 238 * @return an array of FTPFile objects containing the whole list of 239 * files returned by the server as read by this object's parser. 240 * <p><b> 241 * NOTE:</b> This array may contain null members if any of the 242 * individual file listings failed to parse. The caller should 243 * check each entry for null before referencing it, or use the 244 * a filter such as {@link FTPFileFilters#NON_NULL} which does not 245 * allow null entries. 246 * @since 2.2 247 * @exception IOException 248 */ 249 public FTPFile[] getFiles(FTPFileFilter filter) 250 throws IOException 251 { 252 List<FTPFile> tmpResults = new ArrayList<FTPFile>(); 253 Iterator<String> iter = this.entries.iterator(); 254 while (iter.hasNext()) { 255 String entry = iter.next(); 256 FTPFile temp = this.parser.parseFTPEntry(entry); 257 if (filter.accept(temp)){ 258 tmpResults.add(temp); 259 } 260 } 261 return tmpResults.toArray(new FTPFile[tmpResults.size()]); 262 263 } 264 265 /** 266 * convenience method to allow clients to know whether this object's 267 * internal iterator's current position is at the end of the list. 268 * 269 * @return true if internal iterator is not at end of list, false 270 * otherwise. 271 */ 272 public boolean hasNext() { 273 return _internalIterator.hasNext(); 274 } 275 276 /** 277 * convenience method to allow clients to know whether this object's 278 * internal iterator's current position is at the beginning of the list. 279 * 280 * @return true if internal iterator is not at beginning of list, false 281 * otherwise. 282 */ 283 public boolean hasPrevious() { 284 return _internalIterator.hasPrevious(); 285 } 286 287 /** 288 * resets this object's internal iterator to the beginning of the list. 289 */ 290 public void resetIterator() { 291 this._internalIterator = this.entries.listIterator(); 292 } 293 294 // DEPRECATED METHODS - for API compatibility only - DO NOT USE 295 296 /** 297 * Do not use. 298 * @deprecated use {@link #readServerList(InputStream, String)} instead 299 */ 300 @Deprecated 301 public void readServerList(InputStream stream) 302 throws IOException 303 { 304 readServerList(stream, null); 305 } 306 307 }