FilterInputStream contains
some other input stream, which it uses as
its basic source of data, possibly transforming
the data along the way or providing additional
functionality. The class FilterInputStream
itself simply overrides all methods of
InputStream with versions that
pass all requests to the contained input
stream. Subclasses of FilterInputStream
may further override some of these methods
and may also provide additional methods
and fields.
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.
-1 if the end of the
stream is reached.IOException if an I/O error occurs.inbyte.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.
b the buffer into which the data is read.-1 if there is no more data because the end of
the stream has been reached.IOException if an I/O error occurs.read(byte[],int,int)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.
b the buffer into which the data is read.off the start offset in the destination array blen the maximum number of bytes read.-1 if there is no more data because the end of
the stream has been reached.java.lang.NullPointerException If b is null.java.lang.IndexOutOfBoundsException If off is negative,
len is negative, or len is greater than
b.length - offIOException if an I/O error occurs.in
This method returns the result of in.available().
IOException if an I/O error occurs.in.close().
IOException if an I/O error occurs.inreset 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).
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.
IOException if the stream has not been marked or if the
mark has been invalidated.inmark(int)mark
and reset methods.
This method
simply performs in.markSupported().
true if this stream type supports the
mark and reset method;
false otherwise.inInputStream.mark(int)InputStream.reset()