Class FTPListParseEngine
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.
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Field Summary
FieldsModifier and TypeFieldDescriptionprivate static final FTPFile[]
An empty immutableFTPFile
array.private ListIterator<String>
private final FTPFileEntryParser
private final boolean
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Constructor Summary
ConstructorsConstructorDescriptionFTPListParseEngine
(FTPFileEntryParser parser) FTPListParseEngine
(FTPFileEntryParser parser, FTPClientConfig configuration) Intended for use by FTPClient only -
Method Summary
Modifier and TypeMethodDescriptionFTPFile[]
getFiles()
Returns an array of FTPFile objects containing the whole list of files returned by the server as read by this object's parser.FTPFile[]
getFiles
(FTPFileFilter filter) Returns an array of FTPFile objects containing the whole list of files returned by the server as read by this object's parser.FTPFile[]
getNext
(int quantityRequested) Returns an array of at mostquantityRequested
FTPFile objects starting at this object's internal iterator's current position.FTPFile[]
getPrevious
(int quantityRequested) Returns an array of at mostquantityRequested
FTPFile objects starting at this object's internal iterator's current position, and working back toward the beginning.boolean
hasNext()
convenience method to allow clients to know whether this object's internal iterator's current position is at the end of the list.boolean
convenience method to allow clients to know whether this object's internal iterator's current position is at the beginning of the list.private void
read
(InputStream inputStream, String charsetName) Internal method for reading (and closing) the input into theentries
list.void
readServerList
(InputStream inputStream) Deprecated.void
readServerList
(InputStream inputStream, String charsetName) Reads (and closes) the initial reading and preparsing of the list returned by the server.void
resets this object's internal iterator to the beginning of the list.
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Field Details
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entries
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internalIterator
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parser
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saveUnparseableEntries
private final boolean saveUnparseableEntries -
EMPTY_FTP_FILE_ARRAY
An empty immutableFTPFile
array.
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Constructor Details
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FTPListParseEngine
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FTPListParseEngine
FTPListParseEngine(FTPFileEntryParser parser, FTPClientConfig configuration) Intended for use by FTPClient only- Since:
- 3.4
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Method Details
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readServerList
Reads (and closes) 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.- Parameters:
inputStream
- input stream provided by the server socket.charsetName
- the encoding to be used for reading the stream- Throws:
IOException
- thrown on any failure to read from the sever.
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read
Internal method for reading (and closing) the input into theentries
list. After this method has completed,entries
will contain a collection of entries (as defined byFTPFileEntryParser.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.- Parameters:
inputStream
- The socket stream on which the input will be read.charsetName
- The encoding to use.- Throws:
IOException
- thrown on any failure to read the stream
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getNext
Returns an array of at mostquantityRequested
FTPFile objects starting at this object's internal iterator's current position. If fewer thanquantityRequested
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.- Parameters:
quantityRequested
- the maximum number of entries we want to get.- Returns:
- 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.
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getPrevious
Returns an array of at mostquantityRequested
FTPFile objects starting at this object's internal iterator's current position, and working back toward the beginning. If fewer thanquantityRequested
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.- Parameters:
quantityRequested
- the maximum number of entries we want to get.- Returns:
- 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.
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getFiles
Returns an array of FTPFile objects containing the whole list of files returned by the server as read by this object's parser.- Returns:
- 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
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getFiles
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.- Parameters:
filter
- FTPFileFilter, must not benull
.- Returns:
- 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
FTPFileFilters.NON_NULL
which does not allow null entries. - Throws:
IOException
- - not ever thrown, may be removed in a later release- Since:
- 2.2
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hasNext
public boolean hasNext()convenience method to allow clients to know whether this object's internal iterator's current position is at the end of the list.- Returns:
- true if internal iterator is not at end of list, false otherwise.
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hasPrevious
public boolean hasPrevious()convenience method to allow clients to know whether this object's internal iterator's current position is at the beginning of the list.- Returns:
- true if internal iterator is not at beginning of list, false otherwise.
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resetIterator
public void resetIterator()resets this object's internal iterator to the beginning of the list. -
readServerList
Deprecated.usereadServerList(InputStream, String)
insteadDo not use.- Parameters:
inputStream
- the stream from which to read- Throws:
IOException
- on error
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readServerList(InputStream, String)
instead