net.dempsy.util.io

Class MessageBufferOutput

java.lang.Object

java.io.OutputStream

net.dempsy.util.io.MessageBufferOutput

All Implemented Interfaces:

Closeable, Flushable, AutoCloseable

public class MessageBufferOutput
extends OutputStream

This is literally a copy of the ByteArrayOutputStream from the runtime library except it's been modified in the following ways:

• All synchronization has been removed.
• The internal buffer's length is cached in a separate variable to avoid repeated dereferencing of the byte[] object
• You can access the underlying buffer directly using getBuffer().
• Has a grow() method to externally increase the internal buffer size.
• Has a replace(byte[]) method that will allow replacing the underlying buffer with a different one.
• Has a setPosition(int) method that will set the current output position.
• The 'size' method is renamed to getPosition() for clarity.
• Various DataOutputStream write methods have been added.

Remember, with great power comes great responsibility

Field Summary

Fields

Modifier and Type	Field and Description
protected byte[]	buf The buffer where data is stored.
protected int	length This is a cache for the length of the underlying byte[] to avoid constant dereferencing.
protected int	position The number of valid bytes in the buffer.

Constructor Summary

Constructors

Constructor and Description
MessageBufferOutput() Creates a new byte array output stream.
MessageBufferOutput(int size) Creates a new byte array output stream, with a buffer capacity of the specified size, in bytes.

Method Summary

Modifier and Type	Method and Description
void	close() Closing a ByteArrayOutputStream has no effect.
byte[]	getBuffer() Returns the underlying byte[]
int	getPosition() Returns the current position in the buffer where the next byte will be written to.
void	grow() Doubles the internal buffer size while preserving the data
void	grow(int newcap) Doubles the internal buffer size, or sets to the capacity provided if that's higher, while preserving the data
void	replace(byte[] buffer) Completely replace the underlying buffer.
void	reset() Resets the count field of this byte array output stream to zero, so that all currently accumulated output in the output stream is discarded.
void	setPosition(int newPosition) Explicitly set the current position in the buffer.
byte[]	toByteArray() Creates a newly allocated byte array.
String	toString() Converts the buffer's contents into a string decoding bytes using the platform's default character set.
String	toString(String charsetName) Converts the buffer's contents into a string by decoding the bytes using the specified Charset name.
void	write(byte[] b, int off, int len) Writes len bytes from the specified byte array starting at offset off to this byte array output stream.
void	write(int b) Writes the specified byte to this byte array output stream.
void	writeInt(int v) Writes an int to the underlying buffer as four bytes, high byte first.
void	writeShort(short x)
void	writeTo(OutputStream out) Writes the complete contents of this byte array output stream to the specified output stream argument, as if by calling the output stream's write method using out.write(buf, 0, count).

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

buf

protected byte[] buf

The buffer where data is stored.

position

protected int position

The number of valid bytes in the buffer.

length

protected int length

This is a cache for the length of the underlying byte[] to avoid constant dereferencing.

Constructor Detail

MessageBufferOutput

public MessageBufferOutput()

Creates a new byte array output stream. The buffer capacity is initially 32 bytes, though its size increases if necessary.

MessageBufferOutput

public MessageBufferOutput(int size)

Creates a new byte array output stream, with a buffer capacity of the specified size, in bytes.

Parameters:

size - the initial size.

Throws:

IllegalArgumentException - if size is negative.

Method Detail

grow

public void grow()

Doubles the internal buffer size while preserving the data

grow

public void grow(int newcap)

Doubles the internal buffer size, or sets to the capacity provided if that's higher, while preserving the data

replace

public void replace(byte[] buffer)

Completely replace the underlying buffer.

setPosition

public void setPosition(int newPosition)

Explicitly set the current position in the buffer.

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:

ByteArrayOutputStream.size()

write

public void write(int b)

Writes the specified byte to this byte array output stream.

Specified by:

write in class OutputStream

Parameters:

b - the byte to be written.

write

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

Writes len bytes from the specified byte array starting at offset off to this byte array output stream.

Overrides:

write in class OutputStream

Parameters:

b - the data.

off - the start offset in the data.

len - the number of bytes to write.

writeShort

public void writeShort(short x)

writeInt

public void writeInt(int v)
              throws IOException

Writes an int to the underlying buffer as four bytes, high byte first.

Throws:

IOException

writeTo

public void writeTo(OutputStream out)
             throws IOException

Writes the complete contents of this byte array output stream to the specified output stream argument, as if by calling the output stream's write method using out.write(buf, 0, count).

Parameters:

out - the output stream to which to write the data.

Throws:

IOException - if an I/O error occurs.

reset

public void reset()

Resets the count field of this byte array output stream to zero, so that all currently accumulated output in the output stream is discarded. The output stream can be used again, reusing the already allocated buffer space.

getBuffer

public byte[] getBuffer()

Returns the underlying byte[]

Returns:

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

getPosition

public int getPosition()

Returns the current position in the buffer where the next byte will be written to.

Returns:

the value of the count field, which is the number of valid bytes in this output stream.

toString

public String toString()

Converts 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 Object

Returns:

String decoded from the buffer's contents.

Since:

JDK1.1

toString

public String toString(String charsetName)
                throws UnsupportedEncodingException

Converts the buffer's contents into a string by decoding the bytes using the specified Charset name. The length of the new String is a function of the charset, and hence may not be equal to the length of the byte array.

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

Parameters:

charsetName - the name of a supported Charset charset

Returns:

String decoded from the buffer's contents.

Throws:

UnsupportedEncodingException - If the named charset is not supported

Since:

JDK1.1

close

public void close()

Closing a ByteArrayOutputStream has no effect. The methods in this class can be called after the stream has been closed without generating an IOException.

Specified by:

close in interface Closeable

Specified by:

close in interface AutoCloseable

Overrides:

close in class OutputStream