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org.apache.derby.iapi.services.io
Class DynamicByteArrayOutputStream  

java.lang.Object
  java.io.OutputStream
      org.apache.derby.iapi.services.io.DynamicByteArrayOutputStream

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public class DynamicByteArrayOutputStream

extends java.io.OutputStream

A DynamicByteArrayOutputStream allows writing to a dynamically resizable array of bytes. In addition to dynamic resizing, this extension allows the user of this class to have more control over the position of the stream and can get a direct reference of the array.

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Field Summary
private  int	beginPosition
private  byte[]	buf
private static int	INITIAL_SIZE
private  int	position
private  int	used

 

Constructor Summary

DynamicByteArrayOutputStream()

DynamicByteArrayOutputStream(byte[] data)

DynamicByteArrayOutputStream(DynamicByteArrayOutputStream toBeCloned)

DynamicByteArrayOutputStream(int size)

 

Method Summary
void	close()           This method closes the stream.
void	discardLeft(int amountToShrinkBy)           Shrink the buffer left by the amount given.
private  void	expandBuffer(int minExtension)           Expand the buffer by at least the number of bytes requested in minExtension.
int	getBeginPosition()           Get the current position in the stream
byte[]	getByteArray()           Get a reference to the byte array stored in the byte array output stream.
int	getPosition()           Get the current position in the stream
int	getUsed()           Get the number of bytes that was used.
void	reset()           Reset the stream for reuse
void	setBeginPosition(int newBeginPosition)           Set the begin position of the stream pointer.
void	setPosition(int newPosition)           Set the position of the stream pointer.
void	write(byte[] b, int off, int len)           This method writes len bytes from the specified array b starting at index off into the array.
void	write(int b)           This method writes a single byte to the output stream.
(package private)  void	writeCompleteStream(java.io.InputStream dataIn, int len)

 

Methods inherited from class java.io.OutputStream

flush, write

 

Methods inherited from class java.lang.Object

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

 

Field Detail

INITIAL_SIZE

private static int INITIAL_SIZE

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buf

private byte[] buf

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position

private int position

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used

private int used

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beginPosition

private int beginPosition

Constructor Detail

DynamicByteArrayOutputStream

public DynamicByteArrayOutputStream()

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DynamicByteArrayOutputStream

public DynamicByteArrayOutputStream(int size)

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DynamicByteArrayOutputStream

public DynamicByteArrayOutputStream(byte[] data)

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DynamicByteArrayOutputStream

public DynamicByteArrayOutputStream(DynamicByteArrayOutputStream toBeCloned)

Method Detail

write

public void write(int b)

Description copied from class: java.io.OutputStream

This method writes a single byte to the output stream. The byte written is the low eight bits of the int passed and a argument.

Subclasses must provide an implementation of this abstract method

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write

public void write(byte[] b,
                  int off,
                  int len)

Description copied from class: java.io.OutputStream

This method writes len bytes from the specified array b starting at index off into the array.

This method in this class calls the single byte write() method in a loop until all bytes have been written. Subclasses should override this method if possible in order to provide a more efficent implementation.

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writeCompleteStream

void writeCompleteStream(java.io.InputStream dataIn,
                         int len)
                   throws java.io.IOException

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close

public void close()

Description copied from class: java.io.OutputStream

This method closes the stream. Any internal or native resources associated with this stream are freed. Any subsequent attempt to access the stream might throw an exception.

This method in this class does nothing.

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reset

public void reset()

Reset the stream for reuse

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getByteArray

public byte[] getByteArray()

Get a reference to the byte array stored in the byte array output stream. Note that the byte array may be longer that getPosition(). Bytes beyond and including the current poistion are invalid.

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getUsed

public int getUsed()

Get the number of bytes that was used.

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getPosition

public int getPosition()

Get the current position in the stream

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getBeginPosition

public int getBeginPosition()

Get the current position in the stream

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setPosition

public void setPosition(int newPosition)

Set the position of the stream pointer. It is up to the caller to make sure the stream has no gap of garbage in it or useful information is not left out at the end because the stream does not remember anything about the previous position.

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setBeginPosition

public void setBeginPosition(int newBeginPosition)

Set the begin position of the stream pointer. If the newBeginPosition is larger than the stream itself, then, the begin position is not set.

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discardLeft

public void discardLeft(int amountToShrinkBy)

Shrink the buffer left by the amount given. Ie. bytes from 0 to amountToShrinkBy are thrown away

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expandBuffer

private void expandBuffer(int minExtension)

Expand the buffer by at least the number of bytes requested in minExtension. To optimize performance and reduce memory copies and allocation, we have a staged buffer expansion.

• buf.length < 128k - increase by 4k
• buf.length < 1Mb - increase by 128k
• otherwise increase by 1Mb.

In all cases, if minExpansion is greater than the value about then the buffer will be increased by minExtension.

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