Class FilterInputStream

Field Detail

• in

  protected volatile InputStream in

  The input stream to be filtered.

Constructor Detail

• FilterInputStream

  protected FilterInputStream(InputStream in)

  Creates a FilterInputStream by assigning the argument in to the field this.in so as to remember it for later use.

  Parameters:

  in - the underlying input stream, or null if this instance is to be created without an underlying stream.

Method Detail

• read

  public int read()
           throws IOException

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

  This method simply performs in.read() and returns the result.

  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.

  See Also:

  in

• read

  public int read(byte[] b)
           throws IOException

  Reads up to byte.length bytes of data from this input stream into an array of bytes. This method blocks until some input is available.

  This method simply performs the call read(b, 0, b.length) and returns the result. It is important that it does not do in.read(b) instead; certain subclasses of FilterInputStream depend on the implementation strategy actually used.

  Overrides:

  read in class InputStream

  Parameters:

  b - the buffer into which the data is 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:

  read(byte[], int, int)

• read

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

  Reads up to len bytes of data from this input stream into an array of bytes. If len is not zero, the method blocks until some input is available; otherwise, no bytes are read and 0 is returned.

  This method simply performs in.read(b, off, len) and returns the result.

  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

  IOException - if an I/O error occurs.

  See Also:

  in

• skip

  public long skip(long n)
            throws IOException

  Skips over and discards n bytes of data from the input stream. The skip method may, for a variety of reasons, end up skipping over some smaller number of bytes, possibly 0. The actual number of bytes skipped is returned.

  This method simply performs in.skip(n).

  Overrides:

  skip in class InputStream

  Parameters:

  n - the number of bytes to be skipped.

  Returns:

  the actual number of bytes skipped.

  Throws:

  IOException - if the stream does not support seek, or if some other I/O error occurs.

• available

  public int available()
                throws IOException

  Returns an estimate of 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. A single read or skip of this many bytes will not block, but may read or skip fewer bytes.

  This method returns the result of in.available().

  Overrides:

  available in class InputStream

  Returns:

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

  Throws:

  IOException - if an I/O error occurs.

• close

  public void close()
             throws IOException

  Closes this input stream and releases any system resources associated with the stream. This method simply performs in.close().

  Specified by:

  close in interface Closeable

  Specified by:

  close in interface AutoCloseable

  Overrides:

  close in class InputStream

  Throws:

  IOException - if an I/O error occurs.

  See Also:

  in

• 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 argument tells this input stream to allow that many bytes to be read before the mark position gets invalidated.

  This method simply performs in.mark(readlimit).

  Overrides:

  mark in class InputStream

  Parameters:

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

  See Also:

  in, reset()

• reset

  public void reset()
             throws IOException

  Repositions this stream to the position at the time the mark method was last called on this input stream.

  This method simply performs in.reset().

  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 parse, it just chugs along happily. If the stream is not of that type, the parser should toss an exception when it fails. If this happens within readlimit bytes, it allows the outer code to reset the stream and try another parser.

  Overrides:

  reset in class InputStream

  Throws:

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

  See Also:

  in, mark(int)

• markSupported

  public boolean markSupported()

  Tests if this input stream supports the mark and reset methods. This method simply performs in.markSupported().

  Overrides:

  markSupported in class InputStream

  Returns:

  true if this stream type supports the mark and reset method; false otherwise.

  See Also:

  in, InputStream.mark(int), InputStream.reset()