com.livescribe.ext.io
Class BufferedInputStream

java.lang.Object
  java.io.InputStream
      com.livescribe.ext.io.BufferedInputStream

public class BufferedInputStream
extends InputStream

This adds the ability to buffer input. An internal buffer is refilled as necessary. This does not implement the mark/reset functionality.

This class is helpful, for example, when using a DataInputStream since that class may use single-byte reads when constructing larger primitive types. The underlying stream may be poorly buffered.

Since:

2.5

Field Summary

protected byte[]	buf The internal buffer.
protected int	count The number of valid bytes in the buffer, in the range 0–buf.length.
protected InputStream	in The wrapped input stream.
protected int	pos The current buffer position, pointing to the next byte to be read from the buffer.

Constructor Summary

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

Method Summary

int	available() Returns the number of bytes that can be read (or skipped over) from this input stream without blocking by the next caller of a method for this input stream.
void	close() Can asynchronously close this stream.
int	read() Reads the next byte of data from the input stream.
int	read(byte[] b, int off, int len) Reads up to len bytes of data from the input stream into an array of bytes.
long	skip(long n) Skips over and discards n bytes of data from this input stream.

Methods inherited from class java.io.InputStream

mark, markSupported, read, reset

Methods inherited from class java.lang.Object

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

Field Detail

in

protected volatile InputStream in

The wrapped input stream.

buf

protected volatile byte[] buf

The internal buffer.

count

protected int count

The number of valid bytes in the buffer, in the range 0–buf.length.

pos

protected int pos

The current buffer position, pointing to the next byte to be read from the buffer. This will be in the range 0–count. If it is equal to count then more bytes will need to be read from the underlying stream for the next read or skip call.

Constructor Detail

BufferedInputStream

public BufferedInputStream(InputStream in,
                           int bufSize)

Creates a new buffered input stream having the specified buffer size.

Parameters:

in - the input stream

bufSize - the buffer size

Throws:

IllegalArgumentException - if the buffer size is ≤ zero.

Method Detail

read

public int read()
         throws IOException

Description copied from class: InputStream

Reads the next byte of data from the 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 method blocks until input data is available, the end of the stream is detected, or an exception is thrown.

A subclass must provide an implementation of this method.

Specified by:

read in class InputStream

Returns:

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

Throws:

IOException - if an I/O error occurs.

read

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

Description copied from class: InputStream

Reads up to len bytes of data from the input stream into an array of bytes. An attempt is made to read as many as len bytes, but a smaller number may be read, possibly zero. The number of bytes actually read is returned as an integer.

This method blocks until input data is available, end of file is detected, or an exception is thrown.

If b is null, a NullPointerException is thrown.

If off is negative, or len is negative, or off+len is greater than the length of the array b, then an IndexOutOfBoundsException is thrown.

If len is zero, then no bytes are read and 0 is returned; otherwise, there is an attempt to read at least one byte. If no byte is available because the stream is at end of file, the value -1 is returned; otherwise, at least one byte is read and stored into b.

The first byte read is stored into element b[off], the next one into b[off+1], and so on. The number of bytes read is, at most, equal to len. Let k be the number of bytes actually read; these bytes will be stored in elements b[off] through b[off+k-1], leaving elements b[off+k] through b[off+len-1] unaffected.

In every case, elements b[0] through b[off] and elements b[off+len] through b[b.length-1] are unaffected.

If the first byte cannot be read for any reason other than end of file, then an IOException is thrown. In particular, an IOException is thrown if the input stream has been closed.

The read(b, off, len) method for class InputStream simply calls the method read() repeatedly. If the first such call results in an IOException, that exception is returned from the call to the read(b, off, len) method. If any subsequent call to read() results in a IOException, the exception is caught and treated as if it were end of file; the bytes read up to that point are stored into b and the number of bytes read before the exception occurred is returned. Subclasses are encouraged to provide a more efficient implementation of this method.

Overrides:

read in class InputStream

Parameters:

b - the buffer into which the data is read.

off - the start offset in array b at which the data is written.

len - the maximum number of bytes to 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:

IOException - if an I/O error occurs.

See Also:

InputStream.read()

skip

public long skip(long n)
          throws IOException

Description copied from class: InputStream

Skips over and discards n bytes of data from this input stream. The skip method may, for a variety of reasons, end up skipping over some smaller number of bytes, possibly 0. This may result from any of a number of conditions; reaching end of file before n bytes have been skipped is only one possibility. The actual number of bytes skipped is returned. If n is negative, no bytes are skipped.

The skip method of InputStream creates a byte array and then repeatedly reads into it until n bytes have been read or the end of the stream has been reached. Subclasses are encouraged to provide a more efficient implementation of this method.

Overrides:

skip in class InputStream

Parameters:

n - the number of bytes to be skipped.

Returns:

the actual number of bytes skipped.

Throws:

IOException - if an I/O error occurs.

available

public int available()
              throws IOException

Description copied from class: InputStream

Returns the number of bytes that can be read (or skipped over) from this input stream without blocking by the next caller of a method for this input stream. The next caller might be the same thread or another thread.

The available method for class InputStream always returns 0.

This method should be overridden by subclasses.

Overrides:

available in class InputStream

Returns:

the number of bytes that can be read from this input stream without blocking.

Throws:

IOException - if an I/O error occurs.

close

public void close()
           throws IOException

Can asynchronously close this stream.

Overrides:

close in class InputStream

Throws:

IOException - if there was an error while closing the stream.