org.springframework.util

Class FastByteArrayOutputStream

java.lang.Object

java.io.OutputStream

org.springframework.util.FastByteArrayOutputStream

All Implemented Interfaces:

java.io.Closeable, java.io.Flushable, java.lang.AutoCloseable

public class FastByteArrayOutputStream
extends java.io.OutputStream

A speedy alternative to ByteArrayOutputStream. Note that this variant does not extend ByteArrayOutputStream, unlike its sibling ResizableByteArrayOutputStream.

Unlike ByteArrayOutputStream, this implementation is backed by a LinkedList of byte[] instead of 1 constantly resizing byte[]. It does not copy buffers when it gets expanded.

The initial buffer is only created when the stream is first written. There is also no copying of the internal buffer if its contents is extracted with the writeTo(OutputStream) method.

Since:

4.2

Author:

Craig Andrews, Juergen Hoeller

See Also:

resize(int), ResizableByteArrayOutputStream

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
private static class	FastByteArrayOutputStream.FastByteArrayInputStream An implementation of InputStream that reads from a given FastByteArrayOutputStream.

Field Summary

Fields

Modifier and Type	Field and Description
private int	alreadyBufferedSize
private java.util.LinkedList<byte[]>	buffers
private boolean	closed
private static int	DEFAULT_BLOCK_SIZE
private int	index
private int	initialBlockSize
private int	nextBlockSize

Constructor Summary

Constructors

Constructor and Description
FastByteArrayOutputStream() Create a new FastByteArrayOutputStream with the default initial capacity of 256 bytes.
FastByteArrayOutputStream(int initialBlockSize) Create a new FastByteArrayOutputStream with the specified initial capacity.

Method Summary

Modifier and Type	Method and Description
private void	addBuffer(int minCapacity) Create a new buffer and store it in the LinkedList
void	close()
java.io.InputStream	getInputStream() Get an InputStream to retrieve the data in this OutputStream.
private static int	nextPowerOf2(int val) Get the next power of 2 of a number (ex, the next power of 2 of 119 is 128).
void	reset() Reset the contents of this FastByteArrayOutputStream.
void	resize(int targetCapacity) Resize the internal buffer size to a specified capacity.
int	size() Return the number of bytes stored in this FastByteArrayOutputStream.
byte[]	toByteArray() Creates a newly allocated byte array.
byte[]	toByteArrayUnsafe() Convert the stream's data to a byte array and return the byte array.
java.lang.String	toString() Convert the buffer's contents into a string decoding bytes using the platform's default character set.
void	write(byte[] data, int offset, int length)
void	write(int datum)
void	writeTo(java.io.OutputStream out) Write the buffers content to the given OutputStream.

Methods inherited from class java.io.OutputStream

flush, write

Methods inherited from class java.lang.Object

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

Field Detail

DEFAULT_BLOCK_SIZE

private static final int DEFAULT_BLOCK_SIZE

See Also:

Constant Field Values

buffers

private final java.util.LinkedList<byte[]> buffers

initialBlockSize

private final int initialBlockSize

nextBlockSize

private int nextBlockSize

alreadyBufferedSize

private int alreadyBufferedSize

index

private int index

closed

private boolean closed

Constructor Detail

FastByteArrayOutputStream

public FastByteArrayOutputStream()

Create a new FastByteArrayOutputStream with the default initial capacity of 256 bytes.

FastByteArrayOutputStream

public FastByteArrayOutputStream(int initialBlockSize)

Create a new FastByteArrayOutputStream with the specified initial capacity.

Parameters:

initialBlockSize - the initial buffer size in bytes

Method Detail

write

public void write(int datum)
           throws java.io.IOException

Specified by:

write in class java.io.OutputStream

Throws:

java.io.IOException

write

public void write(byte[] data,
                  int offset,
                  int length)
           throws java.io.IOException

Overrides:

write in class java.io.OutputStream

Throws:

java.io.IOException

close

public void close()

Specified by:

close in interface java.io.Closeable

Specified by:

close in interface java.lang.AutoCloseable

Overrides:

close in class java.io.OutputStream

toString

public java.lang.String toString()

Convert the buffer's contents into a string decoding bytes using the platform's default character set. The length of the new String is a function of the character set, and hence may not be equal to the size of the buffer.

This method always replaces malformed-input and unmappable-character sequences with the default replacement string for the platform's default character set. The CharsetDecoder class should be used when more control over the decoding process is required.

Overrides:

toString in class java.lang.Object

Returns:

a String decoded from the buffer's contents

size

public int size()

Return the number of bytes stored in this FastByteArrayOutputStream.

toByteArrayUnsafe

public byte[] toByteArrayUnsafe()

Convert the stream's data to a byte array and return the byte array.

Also replaces the internal structures with the byte array to conserve memory: if the byte array is being made anyways, mind as well as use it. This approach also means that if this method is called twice without any writes in between, the second call is a no-op.

This method is "unsafe" as it returns the internal buffer. Callers should not modify the returned buffer.

Returns:

the current contents of this output stream, as a byte array.

See Also:

size(), toByteArray()

toByteArray

public byte[] toByteArray()

Creates a newly allocated byte array.

Its size is the current size of this output stream and the valid contents of the buffer have been copied into it.

Returns:

the current contents of this output stream, as a byte array.

See Also:

size(), toByteArrayUnsafe()

reset

public void reset()

Reset the contents of this FastByteArrayOutputStream.

All currently accumulated output in the output stream is discarded. The output stream can be used again.

getInputStream

public java.io.InputStream getInputStream()

Get an InputStream to retrieve the data in this OutputStream.

Note that if any methods are called on the OutputStream (including, but not limited to, any of the write methods, reset(), toByteArray(), and toByteArrayUnsafe()) then the InputStream's behavior is undefined.

Returns:

InputStream of the contents of this OutputStream

writeTo

public void writeTo(java.io.OutputStream out)
             throws java.io.IOException

Write the buffers content to the given OutputStream.

Parameters:

out - the OutputStream to write to

Throws:

java.io.IOException

resize

public void resize(int targetCapacity)

Resize the internal buffer size to a specified capacity.

Parameters:

targetCapacity - the desired size of the buffer

Throws:

java.lang.IllegalArgumentException - if the given capacity is smaller than the actual size of the content stored in the buffer already

See Also:

size()

addBuffer

private void addBuffer(int minCapacity)

Create a new buffer and store it in the LinkedList

Adds a new buffer that can store at least minCapacity bytes.

nextPowerOf2

private static int nextPowerOf2(int val)

Get the next power of 2 of a number (ex, the next power of 2 of 119 is 128).