java.io
Class BufferedInputStream

java.lang.Object
  |
  +--java.io.InputStream
        |
        +--java.io.FilterInputStream
              |
              +--java.io.BufferedInputStream

public class BufferedInputStream

extends FilterInputStream

A buffered input stream. This stream lets you read in characters from a stream without causing a read every time. The data is read into a buffer, subsequent reads result in a fast buffer access.

Field Summary

protected byte[]	buf The buffer where data is stored.
protected int	count The number of bytes in the buffer.
protected int	marklimit The maximum readahead allowed after a mark() before subsequent calls to reset() fail.
protected int	markpos The position in the buffer of the current mark.
protected int	pos The current position in the buffer.

Fields inherited from class java.io.FilterInputStream

in

Constructor Summary

BufferedInputStream(InputStream in)
Creates a new buffered stream with a default buffer size.

BufferedInputStream(InputStream in, int size)
Creates a new buffered stream with the specified buffer size.

Method Summary

int	available() Returns the number of bytes that can be read without blocking.
void	mark(int readlimit) Marks the current position in the input stream.
boolean	markSupported() Returns a boolean indicating if this stream type supports mark/reset.
int	read() Reads a byte of data.
int	read(byte[] b, int off, int len) Reads into an array of bytes.
void	reset() Repositions the stream to the last marked position.
long	skip(long n) Skips n bytes of input.

Methods inherited from class java.io.FilterInputStream

close, read

Methods inherited from class java.lang.Object

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

Field Detail

buf

protected byte[] buf

The buffer where data is stored.

count

protected int count

The number of bytes in the buffer.

pos

protected int pos

The current position in the buffer.

markpos

protected int markpos

The position in the buffer of the current mark. This mark is set to -1 if there is no current mark.

marklimit

protected int marklimit

The maximum readahead allowed after a mark() before subsequent calls to reset() fail.

Constructor Detail

BufferedInputStream

public BufferedInputStream(InputStream in)

Creates a new buffered stream with a default buffer size.

Parameters:

in - the input stream

BufferedInputStream

public BufferedInputStream(InputStream in,
                           int size)

Creates a new buffered stream with the specified buffer size.

Parameters:

in - the input stream

size - the buffer size

Method Detail

read

public int read()
         throws IOException

Reads a byte of data. This method will block if no input is available.

Overrides:

read in class FilterInputStream

Returns:

the byte read, or -1 if the end of the stream is reached.

Throws:

IOException - If an I/O error has occurred.

read

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

Reads into an array of bytes. Blocks until some input is available.

Overrides:

read in class FilterInputStream

Parameters:

b - the buffer into which the data is read

off - the start offset of the data

len - the maximum number of bytes read

Returns:

the actual number of bytes read, -1 is returned when the end of the stream is reached.

Throws:

IOException - If an I/O error has occurred.

skip

public long skip(long n)
          throws IOException

Skips n bytes of input.

Overrides:

skip in class FilterInputStream

Parameters:

n - the number of bytes to be skipped

Returns:

the actual number of bytes skipped.

Throws:

IOException - If an I/O error has occurred.

available

public int available()
              throws IOException

Returns the number of bytes that can be read without blocking. This total is the number of bytes in the buffer and the number of bytes available from the input stream.

Overrides:

available in class FilterInputStream

Returns:

the number of available bytes.

IOException

mark

public void mark(int readlimit)

Marks the current position in the input stream. A subsequent call to the reset() method will reposition the stream at the last marked position so that subsequent reads will re-read the same bytes. The stream promises to allow readlimit bytes to be read before the mark position gets invalidated.

Overrides:

mark in class FilterInputStream

Parameters:

readlimit - the maximum limit of bytes allowed to be read before the mark position becomes invalid.

reset

public void reset()
           throws IOException

Repositions the stream to the last marked position. If the stream has not been marked, or if the mark has been invalidated, an IOException is thrown. Stream marks are intended to be used in situations where you need to read ahead a little to see what's in the stream. Often this is most easily done by invoking some general parser. If the stream is of the type handled by the parser, it just chugs along happily. If the stream is not of that type, the parser should toss an exception when it fails. If an exception gets tossed within readlimit bytes, the parser will allow the outer code to reset the stream and to try another parser.

Overrides:

reset in class FilterInputStream

Throws:

IOException - If the stream has not been marked or if the mark has been invalidated.

markSupported

public boolean markSupported()

Returns a boolean indicating if this stream type supports mark/reset.

Overrides:

markSupported in class FilterInputStream

Returns:

true if this stream type supports mark/reset; false otherwise.