net.dempsy.util.io

Class MessageBufferInput

java.lang.Object

java.io.InputStream

net.dempsy.util.io.MessageBufferInput

All Implemented Interfaces:

Closeable, AutoCloseable

public class MessageBufferInput
extends InputStream

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

• All synchronization has been removed.
• You can access the underlying buffer directly using MessageBufferOutput.getBuffer().
• There is a clear() which causes available() to return '0'.
• Has a setPosition(int) method that will set the current position we will be reading from.
• Has a getPosition() which identifies the next byte to be read in..

Remember, with great power comes great responsibility

Field Summary

Fields

Modifier and Type	Field and Description
protected byte[]	buf An array of bytes that was provided by the creator of the stream.
protected int	count The index one greater than the last valid character in the input stream buffer.
protected int	mark The currently marked position in the stream.
protected int	pos The index of the next character to read from the input stream buffer.

Constructor Summary

Constructors

Constructor and Description
MessageBufferInput(byte[] buf) Creates a MessageBufferInput so that it uses buf as its buffer array.
MessageBufferInput(byte[] buf, int offset, int length) Creates ByteArrayInputStream that uses buf as its buffer array.

Method Summary

Modifier and Type	Method and Description
int	available() Returns the number of remaining bytes that can be read (or skipped over) from this input stream.
void	clear() Causes the available() to return 0.
void	close() Closing a ByteArrayInputStream has no effect.
byte[]	getBuffer() Returns the underlying byte[]
int	getLimit()
int	getPosition() Returns the current position in the buffer where the next byte will be read from.
void	mark(int readAheadLimit) Set the current marked position in the stream.
boolean	markSupported() Tests if this InputStream supports mark/reset.
int	read() Reads the next byte of data from this input stream.
int	read(byte[] b, int off, int len) Reads up to len bytes of data into an array of bytes from this input stream.
byte[]	readByteArray()
short	readShort()
void	reset() Resets the buffer to the marked position.
void	setPosition(int newPosition) Explicitly set the current position in the buffer.
long	skip(long n) Skips n bytes of input from this input stream.

Methods inherited from class java.io.InputStream

read

Methods inherited from class java.lang.Object

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

Field Detail

buf

protected final byte[] buf

An array of bytes that was provided by the creator of the stream. Elements buf[0] through buf[count-1] are the only bytes that can ever be read from the stream; element buf[pos] is the next byte to be read.

count

protected final int count

The index one greater than the last valid character in the input stream buffer. This value should always be nonnegative and not larger than the length of buf. It is one greater than the position of the last byte within buf that can ever be read from the input stream buffer.

pos

protected int pos

The index of the next character to read from the input stream buffer. This value should always be nonnegative and not larger than the value of count. The next byte to be read from the input stream buffer will be buf[pos].

mark

protected int mark

The currently marked position in the stream. ByteArrayInputStream objects are marked at position zero by default when constructed. They may be marked at another position within the buffer by the mark() method. The current buffer position is set to this point by the reset() method.

If no mark has been set, then the value of mark is the offset passed to the constructor (or 0 if the offset was not supplied).

Since:

JDK1.1

Constructor Detail

MessageBufferInput

public MessageBufferInput(byte[] buf)

Creates a MessageBufferInput so that it uses buf as its buffer array. The buffer array is not copied. The initial value of pos is 0 and the initial value of count is the length of buf.

Parameters:

buf - the input buffer.

MessageBufferInput

public MessageBufferInput(byte[] buf,
                          int offset,
                          int length)

Creates ByteArrayInputStream that uses buf as its buffer array. The initial value of pos is offset and the initial value of count is the minimum of offset+length and buf.length. The buffer array is not copied. The buffer's mark is set to the specified offset.

Parameters:

buf - the input buffer.

offset - the offset in the buffer of the first byte to read.

length - the maximum number of bytes to read from the buffer.

Method Detail

getBuffer

public byte[] getBuffer()

Returns the underlying byte[]

Returns:

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

clear

public void clear()

Causes the available() to return 0.

setPosition

public void setPosition(int newPosition)

Explicitly set the current position in the buffer.

getPosition

public int getPosition()

Returns the current position in the buffer where the next byte will be read from.

getLimit

public int getLimit()

readByteArray

public byte[] readByteArray()

read

public int read()

Reads the next byte of data from this input stream. The value byte is returned as an int in the range 0 to 255. If no byte is available because the end of the stream has been reached, the value -1 is returned.

This read method cannot block.

Specified by:

read in class InputStream

Returns:

the next byte of data, or -1 if the end of the stream has been reached.

read

public int read(byte[] b,
                int off,
                int len)

Reads up to len bytes of data into an array of bytes from this input stream. If pos equals count, then -1 is returned to indicate end of file. Otherwise, the number k of bytes read is equal to the smaller of len and count-pos. If k is positive, then bytes buf[pos] through buf[pos+k-1] are copied into b[off] through b[off+k-1] in the manner performed by System.arraycopy. The value k is added into pos and k is returned.

This read method cannot block.

Overrides:

read in class InputStream

Parameters:

b - the buffer into which the data is read.

off - the start offset in the destination array b

len - the maximum number of bytes read.

Returns:

the total number of bytes read into the buffer, or -1 if there is no more data because the end of the stream has been reached.

Throws:

NullPointerException - If b is null.

IndexOutOfBoundsException - If off is negative, len is negative, or len is greater than b.length - off

readShort

public short readShort()
                throws IndexOutOfBoundsException

Throws:

IndexOutOfBoundsException

skip

public long skip(long n)

Skips n bytes of input from this input stream. Fewer bytes might be skipped if the end of the input stream is reached. The actual number k of bytes to be skipped is equal to the smaller of n and count-pos. The value k is added into pos and k is returned.

Overrides:

skip in class InputStream

Parameters:

n - the number of bytes to be skipped.

Returns:

the actual number of bytes skipped.

available

public int available()

Returns the number of remaining bytes that can be read (or skipped over) from this input stream.

The value returned is count - pos, which is the number of bytes remaining to be read from the input buffer.

Overrides:

available in class InputStream

Returns:

the number of remaining bytes that can be read (or skipped over) from this input stream without blocking.

markSupported

public boolean markSupported()

Tests if this InputStream supports mark/reset. The markSupported method of ByteArrayInputStream always returns true.

Overrides:

markSupported in class InputStream

Since:

JDK1.1

mark

public void mark(int readAheadLimit)

Set the current marked position in the stream. ByteArrayInputStream objects are marked at position zero by default when constructed. They may be marked at another position within the buffer by this method.

If no mark has been set, then the value of the mark is the offset passed to the constructor (or 0 if the offset was not supplied).

Note: The readAheadLimit for this class has no meaning.

Overrides:

mark in class InputStream

Since:

JDK1.1

reset

public void reset()

Resets the buffer to the marked position. The marked position is 0 unless another position was marked or an offset was specified in the constructor.

Overrides:

reset in class InputStream

close

public void close()
           throws IOException

Closing a ByteArrayInputStream 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 InputStream

Throws:

IOException