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/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.feilong.lib.net.ftp;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;
import java.util.ListIterator;
import com.feilong.lib.net.util.Charsets;
/**
* This class handles the entire process of parsing a listing of
* file entries from the server.
*
* This object defines a two-part parsing mechanism.
*
* The first part is comprised of reading the raw input into an internal
* list of strings. Every item in this list corresponds to an actual
* file. All extraneous matter emitted by the server will have been
* removed by the end of this phase. This is accomplished in conjunction
* with the FTPFileEntryParser associated with this engine, by calling
* its methods readNextEntry() - which handles the issue of
* what delimits one entry from another, usually but not always a line
* feed and preParse() - which handles removal of
* extraneous matter such as the preliminary lines of a listing, removal
* of duplicates on versioning systems, etc.
*
* The second part is composed of the actual parsing, again in conjunction
* with the particular parser used by this engine. This is controlled
* by an iterator over the internal list of strings. This may be done
* either in block mode, by calling the getNext() and
* getPrevious() methods to provide "paged" output of less
* than the whole list at one time, or by calling the
* getFiles() method to return the entire list.
*
* Examples:
*
* Paged access:
*
*
* FTPClient f = FTPClient();
* f.connect(server);
* f.login(username, password);
* FTPListParseEngine engine = f.initiateListParsing(directory);
*
* while (engine.hasNext()){
* FTPFile[] files = engine.getNext(25); // "page size" you want
* //do whatever you want with these files, display them, etc.
* //expensive FTPFile objects not created until needed.
* }
*
*
* For unpaged access, simply use FTPClient.listFiles(). That method
* uses this class transparently.
*
* @version $Id$
*/
public class FTPListParseEngine{
private List entries = new LinkedList<>();
private ListIterator _internalIterator = entries.listIterator();
private final FTPFileEntryParser parser;
// Should invalid files (parse failures) be allowed?
private final boolean saveUnparseableEntries;
public FTPListParseEngine(FTPFileEntryParser parser){
this(parser, null);
}
/**
* Intended for use by FTPClient only
*
* @since 3.4
*/
FTPListParseEngine(FTPFileEntryParser parser, FTPClientConfig configuration){
this.parser = parser;
if (configuration != null){
this.saveUnparseableEntries = configuration.getUnparseableEntries();
}else{
this.saveUnparseableEntries = false;
}
}
/**
* handle the initial reading and preparsing of the list returned by
* the server. After this method has completed, this object will contain
* a list of unparsed entries (Strings) each referring to a unique file
* on the server.
*
* @param stream
* input stream provided by the server socket.
* @param encoding
* the encoding to be used for reading the stream
*
* @throws IOException
* thrown on any failure to read from the sever.
*/
public void readServerList(InputStream stream,String encoding) throws IOException{
this.entries = new LinkedList<>();
readStream(stream, encoding);
this.parser.preParse(this.entries);
resetIterator();
}
/**
* Internal method for reading the input into the entries list.
* After this method has completed, entries will contain a
* collection of entries (as defined by
* FTPFileEntryParser.readNextEntry()), but this may contain
* various non-entry preliminary lines from the server output, duplicates,
* and other data that will not be part of the final listing.
*
* @param stream
* The socket stream on which the input will be read.
* @param encoding
* The encoding to use.
*
* @throws IOException
* thrown on any failure to read the stream
*/
private void readStream(InputStream stream,String encoding) throws IOException{
BufferedReader reader = new BufferedReader(new InputStreamReader(stream, Charsets.toCharset(encoding)));
String line = this.parser.readNextEntry(reader);
while (line != null){
this.entries.add(line);
line = this.parser.readNextEntry(reader);
}
reader.close();
}
/**
* Returns an array of at most quantityRequested FTPFile
* objects starting at this object's internal iterator's current position.
* If fewer than quantityRequested such
* elements are available, the returned array will have a length equal
* to the number of entries at and after after the current position.
* If no such entries are found, this array will have a length of 0.
*
* After this method is called this object's internal iterator is advanced
* by a number of positions equal to the size of the array returned.
*
* @param quantityRequested
* the maximum number of entries we want to get.
*
* @return an array of at most quantityRequested FTPFile
* objects starting at the current position of this iterator within its
* list and at least the number of elements which exist in the list at
* and after its current position.
*
*
* NOTE: This array may contain null members if any of the
* individual file listings failed to parse. The caller should
* check each entry for null before referencing it.
*/
public FTPFile[] getNext(int quantityRequested){
List tmpResults = new LinkedList<>();
int count = quantityRequested;
while (count > 0 && this._internalIterator.hasNext()){
String entry = this._internalIterator.next();
FTPFile temp = this.parser.parseFTPEntry(entry);
if (temp == null && saveUnparseableEntries){
temp = new FTPFile(entry);
}
tmpResults.add(temp);
count--;
}
return tmpResults.toArray(new FTPFile[tmpResults.size()]);
}
/**
* Returns an array of at most quantityRequested FTPFile
* objects starting at this object's internal iterator's current position,
* and working back toward the beginning.
*
* If fewer than quantityRequested such
* elements are available, the returned array will have a length equal
* to the number of entries at and after after the current position.
* If no such entries are found, this array will have a length of 0.
*
* After this method is called this object's internal iterator is moved
* back by a number of positions equal to the size of the array returned.
*
* @param quantityRequested
* the maximum number of entries we want to get.
*
* @return an array of at most quantityRequested FTPFile
* objects starting at the current position of this iterator within its
* list and at least the number of elements which exist in the list at
* and after its current position. This array will be in the same order
* as the underlying list (not reversed).
*
*
* NOTE: This array may contain null members if any of the
* individual file listings failed to parse. The caller should
* check each entry for null before referencing it.
*/
public FTPFile[] getPrevious(int quantityRequested){
List tmpResults = new LinkedList<>();
int count = quantityRequested;
while (count > 0 && this._internalIterator.hasPrevious()){
String entry = this._internalIterator.previous();
FTPFile temp = this.parser.parseFTPEntry(entry);
if (temp == null && saveUnparseableEntries){
temp = new FTPFile(entry);
}
tmpResults.add(0, temp);
count--;
}
return tmpResults.toArray(new FTPFile[tmpResults.size()]);
}
/**
* Returns an array of FTPFile objects containing the whole list of
* files returned by the server as read by this object's parser.
*
* @return an array of FTPFile objects containing the whole list of
* files returned by the server as read by this object's parser.
* None of the entries will be null
* @throws IOException
* - not ever thrown, may be removed in a later release
*/
public FTPFile[] getFiles() throws IOException // TODO remove; not actually thrown
{
return getFiles(FTPFileFilters.NON_NULL);
}
/**
* Returns an array of FTPFile objects containing the whole list of
* files returned by the server as read by this object's parser.
* The files are filtered before being added to the array.
*
* @param filter
* FTPFileFilter, must not be null.
*
* @return an array of FTPFile objects containing the whole list of
* files returned by the server as read by this object's parser.
*
*
* NOTE: This array may contain null members if any of the
* individual file listings failed to parse. The caller should
* check each entry for null before referencing it, or use the
* a filter such as {@link FTPFileFilters#NON_NULL} which does not
* allow null entries.
* @since 2.2
* @throws IOException
* - not ever thrown, may be removed in a later release
*/
public FTPFile[] getFiles(FTPFileFilter filter) throws IOException // TODO remove; not actually thrown
{
List tmpResults = new ArrayList<>();
Iterator iter = this.entries.iterator();
while (iter.hasNext()){
String entry = iter.next();
FTPFile temp = this.parser.parseFTPEntry(entry);
if (temp == null && saveUnparseableEntries){
temp = new FTPFile(entry);
}
if (filter.accept(temp)){
tmpResults.add(temp);
}
}
return tmpResults.toArray(new FTPFile[tmpResults.size()]);
}
/**
* convenience method to allow clients to know whether this object's
* internal iterator's current position is at the end of the list.
*
* @return true if internal iterator is not at end of list, false
* otherwise.
*/
public boolean hasNext(){
return _internalIterator.hasNext();
}
/**
* convenience method to allow clients to know whether this object's
* internal iterator's current position is at the beginning of the list.
*
* @return true if internal iterator is not at beginning of list, false
* otherwise.
*/
public boolean hasPrevious(){
return _internalIterator.hasPrevious();
}
/**
* resets this object's internal iterator to the beginning of the list.
*/
public void resetIterator(){
this._internalIterator = this.entries.listIterator();
}
// DEPRECATED METHODS - for API compatibility only - DO NOT USE
/**
* Do not use.
*
* @param stream
* the stream from which to read
* @throws IOException
* on error
* @deprecated use {@link #readServerList(InputStream, String)} instead
*/
@Deprecated
public void readServerList(InputStream stream) throws IOException{
readServerList(stream, null);
}
}