com.lizardtech.djvu
Class DataPool

java.lang.Object
  com.lizardtech.djvu.DjVuObject
      com.lizardtech.djvu.DataPool

All Implemented Interfaces:

DjVuInterface, java.lang.Cloneable

public class DataPool
extends DjVuObject
implements java.lang.Cloneable

This class impliments a random access view of buffered data.

Version:

$Revision: 1.10 $

Author:

Bill C. Riemers

Nested Class Summary

class

DataPool.CachedInputStream This class is an input stream which spans the accessable data in a DataPool object.

Field Summary

static java.util.Hashtable

cache Object for caching raw data.

Fields inherited from class com.lizardtech.djvu.DjVuObject

hasReferences

Constructor Summary

DataPool()
Creates a new DataPool object.

Method Summary

java.lang.Object	clone() Create a copy of this data pool which will refere to the original as a parent to read data.
ByteVector	createByteVector() Create a new ByteVector.
static DataPool	createDataPool(DjVuInterface ref) Creates an instance of DataPool with the options interherited from the specified reference.
static DataPool	createDataPool(DjVuInterface ref, java.net.URL url) Called to convert a URL to a DataPool.
DataPool.CachedInputStream	createInputStream() Created a DataPool.CachedInputStream to read the data from.
protected ByteVector	getBuffer() Query the buffer.
ByteVector	getData(int targetSize) Read the data of the underlying DataPool up until the targetSize or EOF.
int	getEndOffset() Query the end position of this pool.
DataPool	getParent() Query the parent pool.
int	getPosition() Query the end position of buffered data.
int	getStartOffset() Query the start offset of this pool.
java.net.URL	getUrl() Queries the URL used to create this stream.
DataPool	init(DataPool parent, int startOffset, int endOffset) Initialize this pool to read data from a parent using the specified range.
DataPool	init(java.io.InputStream input) Initialize the DataPool with the specified input stream
DataPool	init(java.net.URL url, boolean prefetch) Initialize the DataPool with the specified url.
void	prefetch() Prefetched datain a separate thread.
java.lang.String	readUTF() Convert the accessable data into a string.
protected void	setBuffer(ByteVector buffer) Set a new buffer.
void	setEndOffset(int offset) Adjust the endOffset of the DataPool.
void	setStartOffset(int offset) Adjust the startOffset of the DataPool.
byte[]	toSizedByteArray() Convert the accessable data into an array of bytes, with the first two bytes equal to the array length.

Methods inherited from class com.lizardtech.djvu.DjVuObject

checkLockTime, create, create, createSoftReference, createWeakReference, getDjVuOptions, getFromReference, invoke, setDjVuOptions

Methods inherited from class java.lang.Object

equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

cache

public static java.util.Hashtable cache

Object for caching raw data. !

Constructor Detail

DataPool

public DataPool()

Creates a new DataPool object.

Method Detail

setEndOffset

public void setEndOffset(int offset)

Adjust the endOffset of the DataPool. This may be decreased, but never increased.

Parameters:

offset - DOCUMENT ME!

getEndOffset

public int getEndOffset()

Query the end position of this pool.

Returns:

the end position

getParent

public DataPool getParent()

Query the parent pool.

Returns:

the parent pool

setStartOffset

public void setStartOffset(int offset)

Adjust the startOffset of the DataPool. This may be increased, but never decreased.

Parameters:

offset - the now start offset of this DataPool

getStartOffset

public int getStartOffset()

Query the start offset of this pool.

Returns:

the start offset

getUrl

public java.net.URL getUrl()

Queries the URL used to create this stream.

Returns:

url used to create this stream or null if created from a non-URL data source

createDataPool

public static DataPool createDataPool(DjVuInterface ref)

Creates an instance of DataPool with the options interherited from the specified reference.

Parameters:

ref - Object to interherit DjVuOptions from.

Returns:

a new instance of DataPool.

createDataPool

public static DataPool createDataPool(DjVuInterface ref,
                                      java.net.URL url)

Called to convert a URL to a DataPool. A simple static caching is used to limit repeated downloads.

Parameters:

ref - Object to interherit DjVuOptions from.

url - The URL to open.

Returns:

The cached DataPool.

getData

public ByteVector getData(int targetSize)
                   throws java.io.IOException

Read the data of the underlying DataPool up until the targetSize or EOF. Even if this is a duplicate DataPool, all data will be present in the ByteVector. Ideally, this method should be protected or private, but some Java 1.1 implimentations require public access to this method.

Parameters:

targetSize - the maximum amount of data to read.

Returns:

a ByteVector containing the data read.

Throws:

java.io.IOException - if an io error occurs.

clone

public java.lang.Object clone()

Create a copy of this data pool which will refere to the original as a parent to read data.

Overrides:

clone in class java.lang.Object

Returns:

the newly created copy

createByteVector

public ByteVector createByteVector()

Create a new ByteVector.

Returns:

the new ByteVector.

createInputStream

public DataPool.CachedInputStream createInputStream()

Created a DataPool.CachedInputStream to read the data from. Each CachedInputStream will be logically separate from eachother, with the exception that they will both share a synchronization lock when reading new data.

Returns:

the new CachedInputStream.

init

public DataPool init(DataPool parent,
                     int startOffset,
                     int endOffset)

Initialize this pool to read data from a parent using the specified range.

Parameters:

parent - pool containing the data source

startOffset - start position to read from

endOffset - end position to read to

Returns:

the initialized pool

init

public DataPool init(java.io.InputStream input)

Initialize the DataPool with the specified input stream

Parameters:

input - stream to read

Returns:

this

init

public DataPool init(java.net.URL url,
                     boolean prefetch)

Initialize the DataPool with the specified url. Data may be prefetched in a separate thread.

Parameters:

url - to read

prefetch - true if data should be prefetched in a separate thread

Returns:

this

prefetch

public void prefetch()

Prefetched datain a separate thread.

readUTF

public java.lang.String readUTF()
                         throws java.io.IOException

Convert the accessable data into a string. First a java modified UTF-8 translation will be tried. If that fails, the data will be converted in the current locale encoding.

Returns:

the newly created string

Throws:

java.io.IOException - if an error occurs

toSizedByteArray

public byte[] toSizedByteArray()
                        throws java.io.IOException

Convert the accessable data into an array of bytes, with the first two bytes equal to the array length.

Returns:

the newly created array

Throws:

java.io.IOException - if an error occurs

setBuffer

protected void setBuffer(ByteVector buffer)

Set a new buffer.

Parameters:

buffer - the new ByteVector to use

getBuffer

protected ByteVector getBuffer()

Query the buffer.

Returns:

the ByteVector used to buffer data

getPosition

public int getPosition()

Query the end position of buffered data.

Returns:

the end position of buffered data.