org.apache.commons.io.input.buffer

Class CircularByteBuffer

java.lang.Object

org.apache.commons.io.input.buffer.CircularByteBuffer

public class CircularByteBuffer
extends Object

A buffer, which doesn't need reallocation of byte arrays, because it reuses a single byte array. This works particularly well, if reading from the buffer takes place at the same time than writing to. Such is the case, for example, when using the buffer within a filtering input stream, like the CircularBufferInputStream.

Constructor Summary

Constructors

Constructor and Description
CircularByteBuffer() Creates a new instance with a reasonable default buffer size (IOUtils.DEFAULT_BUFFER_SIZE).
CircularByteBuffer(int pSize) Creates a new instance with the given buffer size.

Method Summary

Modifier and Type	Method and Description
void	add(byte value) Adds a new byte to the buffer, which will eventually be returned by following invocations of read().
void	add(byte[] targetBuffer, int offset, int length) Adds the given bytes to the buffer.
void	clear() Removes all bytes from the buffer.
int	getCurrentNumberOfBytes() Returns the number of bytes, that are currently present in the buffer.
int	getSpace() Returns the number of bytes, that can currently be added to the buffer.
boolean	hasBytes() Returns, whether the buffer is currently holding, at least, a single byte.
boolean	hasSpace() Returns, whether there is currently room for a single byte in the buffer.
boolean	hasSpace(int count) Returns, whether there is currently room for the given number of bytes in the buffer.
boolean	peek(byte[] sourceBuffer, int offset, int length) Returns, whether the next bytes in the buffer are exactly those, given by sourceBuffer, offset, and length.
byte	read() Returns the next byte from the buffer, removing it at the same time, so that following invocations won't return it again.
void	read(byte[] targetBuffer, int targetOffset, int length) Returns the given number of bytes from the buffer by storing them in the given byte array at the given offset.

Methods inherited from class java.lang.Object

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

Constructor Detail

CircularByteBuffer

public CircularByteBuffer(int pSize)

Creates a new instance with the given buffer size.

Parameters:

pSize - the size of buffer to create

CircularByteBuffer

public CircularByteBuffer()

Creates a new instance with a reasonable default buffer size (IOUtils.DEFAULT_BUFFER_SIZE).

Method Detail

read

public byte read()

Returns the next byte from the buffer, removing it at the same time, so that following invocations won't return it again.

Returns:

The byte, which is being returned.

Throws:

IllegalStateException - The buffer is empty. Use hasBytes(), or getCurrentNumberOfBytes(), to prevent this exception.

read

public void read(byte[] targetBuffer,
                 int targetOffset,
                 int length)

Returns the given number of bytes from the buffer by storing them in the given byte array at the given offset.

Parameters:

targetBuffer - The byte array, where to add bytes.

targetOffset - The offset, where to store bytes in the byte array.

length - The number of bytes to return.

Throws:

NullPointerException - The byte array pBuffer is null.

IllegalArgumentException - Either of pOffset, or pLength is negative, or the length of the byte array pBuffer is too small.

IllegalStateException - The buffer doesn't hold the given number of bytes. Use getCurrentNumberOfBytes() to prevent this exception.

add

public void add(byte value)

Adds a new byte to the buffer, which will eventually be returned by following invocations of read().

Parameters:

value - The byte, which is being added to the buffer.

Throws:

IllegalStateException - The buffer is full. Use hasSpace(), or getSpace(), to prevent this exception.

peek

public boolean peek(byte[] sourceBuffer,
                    int offset,
                    int length)

Returns, whether the next bytes in the buffer are exactly those, given by sourceBuffer, offset, and length. No bytes are being removed from the buffer. If the result is true, then the following invocations of read() are guaranteed to return exactly those bytes.

Parameters:

sourceBuffer - the buffer to compare against

offset - start offset

length - length to compare

Returns:

True, if the next invocations of read() will return the bytes at offsets pOffset+0, pOffset+1, ..., pOffset+pLength-1 of byte array pBuffer.

Throws:

IllegalArgumentException - Either of pOffset, or pLength is negative.

NullPointerException - The byte array pBuffer is null.

add

public void add(byte[] targetBuffer,
                int offset,
                int length)

Adds the given bytes to the buffer. This is the same as invoking add(byte) for the bytes at offsets offset+0, offset+1, ..., offset+length-1 of byte array targetBuffer.

Parameters:

targetBuffer - the buffer to copy

offset - start offset

length - length to copy

Throws:

IllegalStateException - The buffer doesn't have sufficient space. Use getSpace() to prevent this exception.

IllegalArgumentException - Either of pOffset, or pLength is negative.

NullPointerException - The byte array pBuffer is null.

hasSpace

public boolean hasSpace()

Returns, whether there is currently room for a single byte in the buffer. Same as hasSpace(1).

Returns:

true if there is space for a byte

See Also:

hasSpace(int), getSpace()

hasSpace

public boolean hasSpace(int count)

Returns, whether there is currently room for the given number of bytes in the buffer.

Parameters:

count - the byte count

Returns:

true if there is space for the given number of bytes

See Also:

hasSpace(), getSpace()

hasBytes

public boolean hasBytes()

Returns, whether the buffer is currently holding, at least, a single byte.

Returns:

true if the buffer is not empty

getSpace

public int getSpace()

Returns the number of bytes, that can currently be added to the buffer.

Returns:

the number of bytes that can be added

getCurrentNumberOfBytes

public int getCurrentNumberOfBytes()

Returns the number of bytes, that are currently present in the buffer.

Returns:

the number of bytes

clear

public void clear()

Removes all bytes from the buffer.