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org.apache.batik.ext.awt.image.codec
Class MemoryCacheSeekableStream  

java.lang.Object
  java.io.InputStream
      org.apache.batik.ext.awt.image.codec.SeekableStream
          org.apache.batik.ext.awt.image.codec.MemoryCacheSeekableStream

All Implemented Interfaces:

java.io.Closeable, java.io.DataInput

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public final class MemoryCacheSeekableStream

extends SeekableStream

A subclass of SeekableStream that may be used to wrap a regular InputStream. Seeking backwards is supported by means of an in-memory cache. For greater efficiency, FileCacheSeekableStream should be used in circumstances that allow the creation of a temporary file.

The mark() and reset() methods are supported.

This class is not a committed part of the JAI API. It may be removed or changed in future releases of JAI.

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Field Summary
private  java.util.Vector	data           A Vector of source sectors.
(package private)  boolean	foundEOS           True if we've previously reached the end of the source stream
(package private)  int	length           Number of bytes read.
private  long	pointer           Position of first unread byte.
private static int	SECTOR_MASK           A mask to determine the offset within a sector.
private static int	SECTOR_SHIFT           Log_2 of the sector size.
private static int	SECTOR_SIZE           The sector size.
(package private)  int	sectors           Number of sectors stored.
private  java.io.InputStream	src           The source input stream.

 

Fields inherited from class org.apache.batik.ext.awt.image.codec.SeekableStream

markPos

 

Constructor Summary

MemoryCacheSeekableStream(java.io.InputStream src)           Constructs a MemoryCacheSeekableStream that takes its source data from a regular InputStream.

 

Method Summary
boolean	canSeekBackwards()           Returns true since all MemoryCacheSeekableStream instances support seeking backwards.
long	getFilePointer()           Returns the current offset in this file.
int	read()           Reads the next byte of data from the input stream.
int	read(byte[] b, int off, int len)           Reads up to len bytes of data from the input stream into an array of bytes.
private  long	readUntil(long pos)           Ensures that at least pos bytes are cached, or the end of the source is reached.
void	seek(long pos)           Sets the file-pointer offset, measured from the beginning of this file, at which the next read occurs.

 

Methods inherited from class org.apache.batik.ext.awt.image.codec.SeekableStream

finalize, mark, markSupported, readBoolean, readByte, readChar, readCharLE, readDouble, readDoubleLE, readFloat, readFloatLE, readFully, readFully, readInt, readIntLE, readLine, readLong, readLongLE, readShort, readShortLE, readUnsignedByte, readUnsignedInt, readUnsignedIntLE, readUnsignedShort, readUnsignedShortLE, readUTF, reset, skipBytes, wrapInputStream

 

Methods inherited from class java.io.InputStream

available, close, read, skip

 

Methods inherited from class java.lang.Object

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

 

Field Detail

src

private java.io.InputStream src

The source input stream.

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pointer

private long pointer

Position of first unread byte.

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SECTOR_SHIFT

private static final int SECTOR_SHIFT

Log_2 of the sector size.

See Also:

Constant Field Values

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SECTOR_SIZE

private static final int SECTOR_SIZE

The sector size.

See Also:

Constant Field Values

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SECTOR_MASK

private static final int SECTOR_MASK

A mask to determine the offset within a sector.

See Also:

Constant Field Values

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data

private java.util.Vector data

A Vector of source sectors.

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sectors

int sectors

Number of sectors stored.

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length

int length

Number of bytes read.

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foundEOS

boolean foundEOS

True if we've previously reached the end of the source stream

Constructor Detail

MemoryCacheSeekableStream

public MemoryCacheSeekableStream(java.io.InputStream src)

Constructs a MemoryCacheSeekableStream that takes its source data from a regular InputStream. Seeking backwards is supported by means of an in-memory cache.

Method Detail

readUntil

private long readUntil(long pos)
                throws java.io.IOException

Ensures that at least pos bytes are cached, or the end of the source is reached. The return value is equal to the smaller of pos and the length of the source stream.

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canSeekBackwards

public boolean canSeekBackwards()

Returns true since all MemoryCacheSeekableStream instances support seeking backwards.

Overrides:

canSeekBackwards in class SeekableStream

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getFilePointer

public long getFilePointer()

Returns the current offset in this file.

Specified by:

getFilePointer in class SeekableStream

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seek

public void seek(long pos)
          throws java.io.IOException

Sets the file-pointer offset, measured from the beginning of this file, at which the next read occurs.

Specified by:

seek in class SeekableStream

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read

public int read()
         throws java.io.IOException

Reads the next byte of data from the input stream. The value byte is returned as an int in the range 0 to 255. If no byte is available because the end of the stream has been reached, the value -1 is returned. This method blocks until input data is available, the end of the stream is detected, or an exception is thrown.

Specified by:

read in class SeekableStream

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read

public int read(byte[] b,
                int off,
                int len)
         throws java.io.IOException

Reads up to len bytes of data from the input stream into an array of bytes. An attempt is made to read as many as len bytes, but a smaller number may be read, possibly zero. The number of bytes actually read is returned as an integer.

This method blocks until input data is available, end of file is detected, or an exception is thrown.

If b is null, a NullPointerException is thrown.

If off is negative, or len is negative, or off+len is greater than the length of the array b, then an IndexOutOfBoundsException is thrown.

If len is zero, then no bytes are read and 0 is returned; otherwise, there is an attempt to read at least one byte. If no byte is available because the stream is at end of file, the value -1 is returned; otherwise, at least one byte is read and stored into b.

The first byte read is stored into element b[off], the next one into b[off+1], and so on. The number of bytes read is, at most, equal to len. Let k be the number of bytes actually read; these bytes will be stored in elements b[off] through b[off+k-1], leaving elements b[off+k] through b[off+len-1] unaffected.

In every case, elements b[0] through b[off] and elements b[off+len] through b[b.length-1] are unaffected.

If the first byte cannot be read for any reason other than end of file, then an IOException is thrown. In particular, an IOException is thrown if the input stream has been closed.

Specified by:

read in class SeekableStream

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Home >> All >> org >> apache >> batik >> ext >> awt >> image >> [ codec overview ]	PREV CLASS  NEXT CLASS
SUMMARY:  JAVADOC |  SOURCE |  DOWNLOAD | NESTED | FIELD | CONSTR | METHOD	DETAIL: FIELD | CONSTR | METHOD

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