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Interface WriteBuffer

All Known Implementing Classes:

AbstractWriteBuffer, BinaryWriteBuffer, ByteArrayWriteBuffer, ByteBufferWriteBuffer, DelegatingWriteBuffer, MultiBufferWriteBuffer

public interface WriteBuffer

The WriteBuffer interface represents an in-memory block of binary data that is being accumulated (written to). It is analogous to the byte[] inside a Java ByteArrayOutputStream.

Author:

cp 2005.01.18 created, cp 2005.03.21 defining

Nested Class Summary

Nested Classes

Modifier and Type	Interface and Description
static interface	WriteBuffer.BufferOutput The BufferOutput interface represents a DataOutputStream on top of a WriteBuffer.

Method Summary

Modifier and Type	Method and Description
void	clear() Set the length of the buffer as indicated by the length() method to zero.
Object	clone() Create a clone of this WriteBuffer object.
WriteBuffer.BufferOutput	getAppendingBufferOutput() Get a BufferOutput object to write data to this buffer.
WriteBuffer.BufferOutput	getBufferOutput() Get a BufferOutput object to write data to this buffer, starting at the beginning of the WriteBuffer.
WriteBuffer.BufferOutput	getBufferOutput(int of) Get a BufferOutput object to write data to this buffer starting at a particular offset.
int	getCapacity() Determine the number of bytes that the buffer can hold without resizing itself.
int	getMaximumCapacity() Determine the maximum number of bytes that the buffer can hold.
ReadBuffer	getReadBuffer() Get a ReadBuffer object that is a snapshot of this WriteBuffer's data.
ReadBuffer	getUnsafeReadBuffer() Get a ReadBuffer object to read data from this buffer.
WriteBuffer	getWriteBuffer(int of) Obtain a WriteBuffer starting at a particular offset within this WriteBuffer.
WriteBuffer	getWriteBuffer(int of, int cb) Obtain a WriteBuffer for a portion of this WriteBuffer.
int	length() Determine the length of the data that is in the buffer.
void	retain(int of) Starting with the byte at offset of, retain the remainder of this WriteBuffer, such that the byte at offset of is shifted to offset 0, the byte at offset of + 1 is shifted to offset 1, and so on up to the byte at offset length() - 1, which is shifted to offset length() - of - 1.
void	retain(int of, int cb) Starting with the byte at offset of, retain cb bytes in this WriteBuffer, such that the byte at offset of is shifted to offset 0, the byte at offset of + 1 is shifted to offset 1, and so on up to the byte at offset of + cb - 1, which is shifted to offset cb - 1.
Binary	toBinary() Returns a new Binary object that holds the complete contents of this WriteBuffer.
byte[]	toByteArray() Returns a new byte array that holds the complete contents of this WriteBuffer.
void	write(int ofDest, byte b) Store the specified byte at the specified offset within the buffer.
void	write(int ofDest, byte[] abSrc) Store the specified bytes at the specified offset within the buffer.
void	write(int ofDest, byte[] abSrc, int ofSrc, int cbSrc) Store the specified number of bytes from the specified location within the passed byte array at the specified offset within this buffer.
void	write(int ofDest, InputStreaming stream) Store the remaining contents of the specified InputStreaming object at the specified offset within this buffer.
void	write(int ofDest, InputStreaming stream, int cbSrc) Store the specified number of bytes from the specified InputStreaming object at the specified offset within this buffer.
void	write(int ofDest, ReadBuffer bufSrc) Store the contents of the specified ReadBuffer at the specified offset within this buffer.
void	write(int ofDest, ReadBuffer bufSrc, int ofSrc, int cbSrc) Store the specified portion of the contents of the specified ReadBuffer at the specified offset within this buffer.

Method Detail

write

void write(int ofDest,
           byte b)

Store the specified byte at the specified offset within the buffer.

For purposes of side-effects and potential exceptions, this method is functionally equivalent to the following code:

 byte[] abSrc = new byte[1];
 abSrc[0] = b;
 write(ofDest, abSrc, 0, abSrc.length);
 

Parameters:

ofDest - the offset within this buffer to store the passed data

b - the byte to store in this buffer

write

void write(int ofDest,
           byte[] abSrc)

Store the specified bytes at the specified offset within the buffer.

For purposes of side-effects and potential exceptions, this method is functionally equivalent to the following code:

 write(ofDest, abSrc, 0, abSrc.length);
 

Parameters:

ofDest - the offset within this buffer to store the passed data

abSrc - the array of bytes to store in this buffer

Throws:

NullPointerException - if abSrc is null

IndexOutOfBoundsException - if ofDest is negative, or if ofDest + abSrc.length is greater than getMaximumCapacity()

write

void write(int ofDest,
           byte[] abSrc,
           int ofSrc,
           int cbSrc)

Store the specified number of bytes from the specified location within the passed byte array at the specified offset within this buffer.

As a result of this method, the buffer length as reported by the length() method will become Math.max(length(), ofDest + cbSrc).

As a result of this method, the buffer capacity as reported by the getCapacity() method will not change if the new value returned by length() would not exceed the old value returned by getCapacity(); otherwise, the capacity will be increased such that getCapacity() >= length(). Regardless, it is always true that getCapacity() >= length() and getMaximumCapacity() >= getCapacity(). If the buffer capacity cannot be increased due to resource constraints, an undesignated Error or RuntimeException will be thrown, such as OutOfMemoryError.

Parameters:

ofDest - the offset within this buffer to store the passed data

abSrc - the array containing the bytes to store in this buffer

ofSrc - the offset within the passed byte array to copy from

cbSrc - the number of bytes to copy from the passed byte array

Throws:

NullPointerException - if abSrc is null

IndexOutOfBoundsException - if ofDest, ofSrc or cbSrc is negative, if ofSrc + cbSrc is greater than abSrc.length, or if ofDest + cbSrc is greater than getMaximumCapacity()

write

void write(int ofDest,
           ReadBuffer bufSrc)

Store the contents of the specified ReadBuffer at the specified offset within this buffer.

For purposes of side-effects and potential exceptions, this method is functionally equivalent to the following code:

 byte[] abSrc = bufSrc.toByteArray();
 write(ofDest, abSrc, 0, abSrc.length);
 

Parameters:

ofDest - the offset within this buffer to store the passed data

bufSrc - the array of bytes to store in this buffer

Throws:

NullPointerException - if bufSrc is null

IndexOutOfBoundsException - if ofDest is negative, or if ofDest + bufSrc.length() is greater than getMaximumCapacity()

write

void write(int ofDest,
           ReadBuffer bufSrc,
           int ofSrc,
           int cbSrc)

Store the specified portion of the contents of the specified ReadBuffer at the specified offset within this buffer.

For purposes of side-effects and potential exceptions, this method is functionally equivalent to the following code:

 byte[] abSrc = bufSrc.toByteArray(ofSrc, cbSrc);
 write(ofDest, abSrc, 0, abSrc.length);
 

Parameters:

ofDest - the offset within this buffer to store the passed data

bufSrc - the array of bytes to store in this buffer

ofSrc - the offset within the passed ReadBuffer to copy from

cbSrc - the number of bytes to copy from the passed ReadBuffer

Throws:

NullPointerException - if bufSrc is null

IndexOutOfBoundsException - if ofDest, ofSrc or cbSrc is negative, if ofSrc + cbSrc is greater than bufSrc.length(), or if ofDest + cbSrc is greater than getMaximumCapacity()

write

void write(int ofDest,
           InputStreaming stream)
    throws IOException

Store the remaining contents of the specified InputStreaming object at the specified offset within this buffer.

For purposes of side-effects and potential exceptions, this method is functionally similar to the following code:

 ByteArrayOutputStream streamOut = new ByteArrayOutputStream();
 int b;
 while ((b = stream.read()) >= 0)
     {
     streamOut.write(b);
     }
 byte[] abSrc = streamOut.toByteArray();
 write(ofDest, abSrc, 0, abSrc.length);
 

Parameters:

ofDest - the offset within this buffer to store the passed data

stream - the stream of bytes to read and store in this buffer

Throws:

IOException - if an IOException occurs reading from the passed stream

write

void write(int ofDest,
           InputStreaming stream,
           int cbSrc)
    throws IOException

Store the specified number of bytes from the specified InputStreaming object at the specified offset within this buffer.

For purposes of side-effects and potential exceptions, this method is functionally similar to the following code:

 DataInputStream streamData = new DataInputStream(
         new WrapperInputStream(stream));
 byte[] abSrc = new byte[cbSrc];
 streamData.readFully(abSrc);
 write(ofDest, abSrc, 0, abSrc.length);
 

Parameters:

ofDest - the offset within this buffer to store the passed data

stream - the stream of bytes to read and store in this buffer

cbSrc - the exact number of bytes to read from the stream and put in this buffer

Throws:

IOException - if an IOException occurs reading from the passed stream

length

int length()

Determine the length of the data that is in the buffer. This is the actual number of bytes of data that have been written to the buffer, not the capacity of the buffer.

Returns:

the number of bytes of data represented by this WriteBuffer

retain

void retain(int of)

Starting with the byte at offset of, retain the remainder of this WriteBuffer, such that the byte at offset of is shifted to offset 0, the byte at offset of + 1 is shifted to offset 1, and so on up to the byte at offset length() - 1, which is shifted to offset length() - of - 1. After this method, the length of of the buffer as indicated by the length() method will be equal to length() - of.

This method is functionally equivalent to the following code:

 retain(of, length() - of);
 

Parameters:

of - the offset of the first byte within the WriteBuffer that will be retained

Throws:

IndexOutOfBoundsException - if of is negative or if of is greater than length()

retain

void retain(int of,
            int cb)

Starting with the byte at offset of, retain cb bytes in this WriteBuffer, such that the byte at offset of is shifted to offset 0, the byte at offset of + 1 is shifted to offset 1, and so on up to the byte at offset of + cb - 1, which is shifted to offset cb - 1. After this method, the length of the buffer as indicated by the length() method will be equal to cb.

Legal values for the offset of the first byte to retain of are (of >= 0 && of <= length()). Legal values for the number of bytes to retain cb are (cb >= 0 && cb <= length()), such that (of + cb <= length()).

If cb is zero, then this method will have the same effect as clear. If of is zero, then this method will have the effect of truncating the data in the buffer, but no bytes will be shifted within the buffer.

The effect on the capacity of the buffer is implementation-specific; some implementations are expected to retain the same capacity while others are expected to shrink accordingly.

Parameters:

of - the offset of the first byte within the WriteBuffer that will be retained

cb - the number of bytes to retain

Throws:

IndexOutOfBoundsException - if of or cb is negative of if of + cb is greater than length()

clear

void clear()

Set the length of the buffer as indicated by the length() method to zero.

The effect on the capacity of the buffer is implementation-specific; some implementations are expected to retain the same capacity while others are expected to shrink accordingly.

getCapacity

int getCapacity()

Determine the number of bytes that the buffer can hold without resizing itself. In other words, a WriteBuffer has getCapacity() - length() bytes that can be written to it without overflowing the current underlying buffer allocation. Since the buffer is an abstract concept, the actual mechanism for the underlying buffer is not known, but it could be a Java NIO buffer, or a byte array, etc.

Note that if the maximum size returned by getMaximumCapacity() is greater than the current size returned by this method, then the WriteBuffer will automatically resize itself to allocate more space when the amount of data written to it passes the current size.

Returns:

the number of bytes of data that this WriteBuffer can hold without resizing its underlying buffer

getMaximumCapacity

int getMaximumCapacity()

Determine the maximum number of bytes that the buffer can hold. If the maximum size is greater than the current size, then the buffer is expected to resize itself as necessary up to the maximum size in order to contain the data given to it.

Returns:

the maximum number of bytes of data that the WriteBuffer can hold

getWriteBuffer

WriteBuffer getWriteBuffer(int of)

Obtain a WriteBuffer starting at a particular offset within this WriteBuffer.

This is functionally equivalent to:

 return getWriteBuffer(of, getMaximumCapacity() - of);
 

Parameters:

of - the beginning index, inclusive

Returns:

a WriteBuffer that represents a portion of this WriteBuffer

Throws:

IndexOutOfBoundsException - if of is negative, or of is larger than the getMaximumCapacity() of this WriteBuffer object

getWriteBuffer

WriteBuffer getWriteBuffer(int of,
                           int cb)

Obtain a WriteBuffer for a portion of this WriteBuffer.

Use of the resulting buffer will correspond to using this buffer directly but with the offset being passed to the buffer methods automatically having of added. As a result, the length of this buffer can be modified by writing to the new buffer; however, changes made directly to this buffer will not affect the length of the new buffer.

Note that the resulting WriteBuffer is limited in the number of bytes that can be written to it; in other words, its getMaximumCapacity() must return the same value as was passed in cb.

Parameters:

of - the offset of the first byte within this WriteBuffer to map to offset 0 of the new WriteBuffer

cb - the number of bytes to cover in the resulting WriteBuffer

Returns:

a WriteBuffer that represents a portion of this WriteBuffer

Throws:

IndexOutOfBoundsException - if of or cb is negative, or of + cb is larger than the getMaximumCapacity() of this WriteBuffer object

getBufferOutput

WriteBuffer.BufferOutput getBufferOutput()

Get a BufferOutput object to write data to this buffer, starting at the beginning of the WriteBuffer.

This is functionally equivalent to:

 return getBufferOutput(0);
 

Returns:

a BufferOutput that is writing to this buffer starting at offset zero

getBufferOutput

WriteBuffer.BufferOutput getBufferOutput(int of)

Get a BufferOutput object to write data to this buffer starting at a particular offset.

Note that each call to this method will return a new BufferOutput object, with the possible exception being that a zero-length non-resizing WriteBuffer could always return the same instance (since it is not writable).

This is functionally equivalent to:

 BufferOutput bufout = getBufferOutput();
 bufout.setOffset(of);
 return bufout;
 

Parameters:

of - the offset of the first byte of this buffer that the BufferOutput will write to

Returns:

a BufferOutput that will write to this buffer

getAppendingBufferOutput

WriteBuffer.BufferOutput getAppendingBufferOutput()

Get a BufferOutput object to write data to this buffer. The BufferOutput object returned by this method is set to append to the WriteBuffer, meaning that its offset is pre-set to the length() of this buffer.

This is functionally equivalent to:

 return getBufferOutput(length());
 

Returns:

a BufferOutput configured to append to this buffer

getReadBuffer

ReadBuffer getReadBuffer()

Get a ReadBuffer object that is a snapshot of this WriteBuffer's data.

This method is functionally equivalent to the following code:

 ReadBuffer buf = getUnsafeReadBuffer();
 byte[] ab = buf.toByteArray();
 return new ByteArrayReadBuffer(ab);
 

Returns:

a ReadBuffer that reflects the point-in-time contents of this WriteBuffer

getUnsafeReadBuffer

ReadBuffer getUnsafeReadBuffer()

Get a ReadBuffer object to read data from this buffer. This method is not guaranteed to return a snapshot of this buffer's data, nor is it guaranteed to return a live view of this buffer, which means that subsequent changes to this WriteBuffer may or may not affect the contents and / or the length of the returned ReadBuffer.

To get a snapshot, use the getReadBuffer() method.

Returns:

a ReadBuffer that reflects the contents of this WriteBuffer but whose behavior is undefined if the WriteBuffer is modified

toByteArray

byte[] toByteArray()

Returns a new byte array that holds the complete contents of this WriteBuffer.

This method is functionally equivalent to the following code:

 return getUnsafeReadBuffer().toByteArray();
 

Returns:

the contents of this WriteBuffer as a byte[]

toBinary

Binary toBinary()

Returns a new Binary object that holds the complete contents of this WriteBuffer.

This method is functionally equivalent to the following code:

 return getUnsafeReadBuffer().toBinary();
 

Returns:

the contents of this WriteBuffer as a Binary object

clone

Object clone()

Create a clone of this WriteBuffer object. Changes to the clone will not affect the original, and vice-versa.

Returns:

a WriteBuffer object with the same contents as this WriteBuffer object