org.wegra.io
Class MarkableInputStream

java.lang.Object
  java.io.InputStream
      org.wegra.io.MarkableInputStream

public class MarkableInputStream

extends java.io.InputStream

Version:

1.0.0 (2003. 6. 27.)

Author:

wegra(Bok-Youn Lee)

Nested Class Summary

static class

MarkableInputStream.Test Inner class for testing MarkableInputStream

Constructor Summary

MarkableInputStream(java.io.InputStream stream)
Creates a MarkableInputStream and saves its argument, the input stream in, for later use.

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() Closes this input stream and releases any system resources associated with the stream.
void	mark(int readLimit) Marks the current position in this input stream.
boolean	markSupported() Returns true.
int	read() Reads the next byte of data from the input stream.
int	read(byte[] buf) Reads some number of bytes from the input stream and stores them into the buffer array buf.
int	read(byte[] buf, int off, int len) Reads up to len bytes of data from the input stream into an array of bytes.
void	reset() Repositions this stream to the position at the time the mark method was last called on this input stream, if you don't read data over the readLimit since mark method was last called.
long	skip(long length) Skips over and discards length bytes of data from this input stream.

Methods inherited from class java.lang.Object

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

Constructor Detail

MarkableInputStream

public MarkableInputStream(java.io.InputStream stream)

Creates a MarkableInputStream and saves its argument, the input stream in, for later use.

Parameters:

stream - the underlying input stream.

Method Detail

available

public int available()
              throws java.io.IOException

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.

Returns:

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

Throws:

java.io.IOException

close

public void close()
           throws java.io.IOException

Closes this input stream and releases any system resources associated with the stream.

Throws:

java.io.IOException

mark

public void mark(int readLimit)

Marks the current position in this input stream. A subsequent call to the reset method repositions this stream at the last marked position so that subsequent reads re-read the same bytes.

The readlimit arguments tells this input stream to allow that many bytes to be read before the mark position gets invalidated.

The general contract of mark is that, if the method markSupported returns true, the stream somehow remembers all the bytes read after the call to mark and stands ready to supply those same bytes again if and whenever the method reset is called. However, the stream is not required to remember any data at all if more than readlimit bytes are read from the stream before reset is called.

Parameters:

readLimit - the maximum limit of bytes that can be read before the mark position becomes invalid.

See Also:

reset()

reset

public void reset()
           throws java.io.IOException

Repositions this stream to the position at the time the mark method was last called on this input stream, if you don't read data over the readLimit since mark method was last called.

Throws:

java.io.IOException

See Also:

mark(int), IOException

read

public int read()
         throws java.io.IOException

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.

Returns:

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

Throws:

java.io.IOException - if an I/O error occurs.

markSupported

public boolean markSupported()

Returns true. This stream supports mark/reset operation.

Returns:

true

read

public int read(byte[] buf,
                int off,
                int len)
         throws java.io.IOException

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 buf 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 buf, 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 buf.

The first byte read is stored into element buf[off], the next one into buf[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 buf[off] through buf[off + k - 1] , leaving elements buf[off + k] through buf[off + len - 1] unaffected.

In every case, elements buf[0] through buf[off] and elements buf[off + len] through buf[buf.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.

Parameters:

buf - the buffer into which the data is read.

off - the start offset in array buf 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:

java.io.IOException - if an I/O error occurs.

read

public int read(byte[] buf)
         throws java.io.IOException

Reads some number of bytes from the input stream and stores them into the buffer array buf. 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 buf is null, a NullPointerException is thrown. If the length of buf 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 buf.

The first byte read is stored into element buf[0], the next one into buf[1], and so on. The number of bytes read is, at most, equal to the length of buf. Let k be the number of bytes actually read; these bytes will be stored in elements buf[0] through buf[k-1], leaving elements b[k] through buf[buf.length - 1] 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(buf) method for class MarkableInputStream has the same effect as:

 read(buf, 0, buf.length) 

Parameters:

buf - the buffer into which the data is read.

Returns:

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

Throws:

java.io.IOException - if an I/O error occurs.

See Also:

read(byte[], int, int)

skip

public long skip(long length)
          throws java.io.IOException

Skips over and discards length 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 length bytes have been skipped is only one possibility. The actual number of bytes skipped is returned. If length is negative, no bytes are skipped.

The skip method of InputStream creates a byte array and then repeatedly reads into it until length 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.

Parameters:

length - the number of bytes to be skipped.

Returns:

the actual number of bytes skipped.

Throws:

java.io.IOException - if an I/O error occurs.