org.mbari.siam.utils
Class SiamBufferedInputStream

java.lang.Object
  extended by java.io.InputStream
      extended by java.io.FilterInputStream
          extended by org.mbari.siam.utils.SiamBufferedInputStream
All Implemented Interfaces:
java.io.Closeable

public class SiamBufferedInputStream
extends java.io.FilterInputStream

SiamBufferedInputStream is a slightly Modified GNU Classpath BufferedInputStream. This subclass of FilterInputStream buffers input from an underlying implementation to provide a possibly more efficient read mechanism. It maintains the buffer and buffer state in instance variables that are available to subclasses. The default buffer size of 4096 bytes can be overridden by the creator of the stream.

This class also implements mark/reset functionality. It is capable of remembering any number of input bytes, to the limits of system memory or the size of Integer.MAX_VALUE

Please note that this class does not properly handle character encodings. Consider using the BufferedReader class which does.

Author:
Aaron M. Renn (arenn@urbanophile.com), Warren Levy

Field Summary
protected  byte[] buf
          The buffer used for storing data from the underlying stream.
protected  int count
          The number of valid bytes currently in the buffer.
protected  int marklimit
          This is the maximum number of bytes than can be read after a call to mark() before the mark can be discarded.
protected  int markpos
          The value of pos when the mark() method was called.
protected  int pos
          The index of the next character that will by read from the buffer.
 
Fields inherited from class java.io.FilterInputStream
in
 
Constructor Summary
SiamBufferedInputStream(java.io.InputStream in)
          This method initializes a new BufferedInputStream that will read from the specified subordinate stream with a default buffer size of 2048 bytes
SiamBufferedInputStream(java.io.InputStream in, int size)
          This method initializes a new BufferedInputStream that will read from the specified subordinate stream with a buffer size that is specified by the caller.
 
Method Summary
 int available()
          This method returns the number of bytes that can be read from this stream before a read can block.
 void close()
          This method closes the underlying input stream and frees any resources associated with it.
 void flush()
          Read and discard all available characters.
 void mark(int readlimit)
          This method marks a position in the input to which the stream can be "reset" by calling the reset() method.
 boolean markSupported()
          This method returns true to indicate that this class supports mark/reset functionality.
 int read()
          This method reads an unsigned byte from the input stream and returns it as an int in the range of 0-255.
 int read(byte[] b, int off, int len)
          This method reads bytes from a stream and stores them into a caller supplied buffer.
 void reset()
          This method resets a stream to the point where the mark() method was called.
 long skip(long n)
          This method skips the specified number of bytes in the stream.
 
Methods inherited from class java.io.FilterInputStream
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 used for storing data from the underlying stream.


count

protected int count
The number of valid bytes currently in the buffer. It is also the index of the buffer position one byte past the end of the valid data.


pos

protected int pos
The index of the next character that will by read from the buffer. When pos == count, the buffer is empty.


markpos

protected int markpos
The value of pos when the mark() method was called. This is set to -1 if there is no mark set.


marklimit

protected int marklimit
This is the maximum number of bytes than can be read after a call to mark() before the mark can be discarded. After this may bytes are read, the reset() method may not be called successfully.

Constructor Detail

SiamBufferedInputStream

public SiamBufferedInputStream(java.io.InputStream in)
This method initializes a new BufferedInputStream that will read from the specified subordinate stream with a default buffer size of 2048 bytes

Parameters:
in - The subordinate stream to read from

SiamBufferedInputStream

public SiamBufferedInputStream(java.io.InputStream in,
                               int size)
This method initializes a new BufferedInputStream that will read from the specified subordinate stream with a buffer size that is specified by the caller.

Parameters:
in - The subordinate stream to read from
size - The buffer size to use
Throws:
java.lang.IllegalArgumentException - when size is smaller then 1
Method Detail

available

public int available()
              throws java.io.IOException
This method returns the number of bytes that can be read from this stream before a read can block. A return of 0 indicates that blocking might (or might not) occur on the very next read attempt.

The number of available bytes will be the number of read ahead bytes stored in the internal buffer plus the number of available bytes in the underlying stream.

Overrides:
available in class java.io.FilterInputStream
Returns:
The number of bytes that can be read before blocking could occur
Throws:
java.io.IOException - If an error occurs

close

public void close()
           throws java.io.IOException
This method closes the underlying input stream and frees any resources associated with it. Sets buf to null.

Specified by:
close in interface java.io.Closeable
Overrides:
close in class java.io.FilterInputStream
Throws:
java.io.IOException - If an error occurs.

mark

public void mark(int readlimit)
This method marks a position in the input to which the stream can be "reset" by calling the reset() method. The parameter readlimit is the number of bytes that can be read from the stream after setting the mark before the mark becomes invalid. For example, if mark() is called with a read limit of 10, then when 11 bytes of data are read from the stream before the reset() method is called, then the mark is invalid and the stream object instance is not required to remember the mark.

Note that the number of bytes that can be remembered by this method can be greater than the size of the internal read buffer. It is also not dependent on the subordinate stream supporting mark/reset functionality.

Overrides:
mark in class java.io.FilterInputStream
Parameters:
readlimit - The number of bytes that can be read before the mark becomes invalid

markSupported

public boolean markSupported()
This method returns true to indicate that this class supports mark/reset functionality.

Overrides:
markSupported in class java.io.FilterInputStream
Returns:
true to indicate that mark/reset functionality is supported

read

public int read()
         throws java.io.IOException
This method reads an unsigned byte from the input stream and returns it as an int in the range of 0-255. This method also will return -1 if the end of the stream has been reached.

This method will block until the byte can be read.

Overrides:
read in class java.io.FilterInputStream
Returns:
The byte read or -1 if end of stream
Throws:
java.io.IOException - If an error occurs

read

public int read(byte[] b,
                int off,
                int len)
         throws java.io.IOException
This method reads bytes from a stream and stores them into a caller supplied buffer. It starts storing the data at index off into the buffer and attempts to read len bytes. This method can return before reading the number of bytes requested. The actual number of bytes read is returned as an int. A -1 is returned to indicate the end of the stream.

This method will block until some data can be read.

Overrides:
read in class java.io.FilterInputStream
Parameters:
b - The array into which the bytes read should be stored
off - The offset into the array to start storing bytes
len - The requested number of bytes to read
Returns:
The actual number of bytes read, or -1 if end of stream.
Throws:
java.io.IOException - If an error occurs.
java.lang.IndexOutOfBoundsException - when off or len are negative, or when off + len is larger then the size of b,

reset

public void reset()
           throws java.io.IOException
This method resets a stream to the point where the mark() method was called. Any bytes that were read after the mark point was set will be re-read during subsequent reads.

This method will throw an IOException if the number of bytes read from the stream since the call to mark() exceeds the mark limit passed when establishing the mark.

Overrides:
reset in class java.io.FilterInputStream
Throws:
java.io.IOException - If mark() was never called or more then markLimit bytes were read since the last call to mark()

skip

public long skip(long n)
          throws java.io.IOException
This method skips the specified number of bytes in the stream. It returns the actual number of bytes skipped, which may be less than the requested amount.

Overrides:
skip in class java.io.FilterInputStream
Parameters:
n - The requested number of bytes to skip
Returns:
The actual number of bytes skipped.
Throws:
java.io.IOException - If an error occurs

flush

public void flush()
           throws java.io.IOException
Read and discard all available characters.

Throws:
java.io.IOException


Copyright © 2003 MBARI.

The Monterey Bay Aquarium Research Institute (MBARI) provides this documentation and code "as is", with no warranty, express or implied, of its quality or consistency. It is provided without support and without obligation on the part of MBARI to assist in its use, correction, modification, or enhancement.