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java.lang.Object
|
+----java.io.InputStream
|
+----java.io.FilterInputStream
The class FilterInputStream itself simply overrides
all methods of InputStream with versions that pass
all requests to the underlying input stream. Subclasses of
FilterInputStream may further override some of these
methods as well as provide additional methods and fields.
in
FilterInputStream(InputStream)
available()
close()
mark(int)
markSupported()
mark
and reset methods.
read()
read(byte[])
byte.length bytes of data from this
input stream into an array of bytes.
read(byte[], int, int)
len bytes of data from this input stream
into an array of bytes.
reset()
mark method was last called on this input stream.
skip(long)
n bytes of data from the
input stream.
in
protected InputStream in
FilterInputStream
protected FilterInputStream(InputStream in)
read
public int read() throws IOException
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.
The read method of FilterInputStream
calls the read method of its underlying input stream
and returns whatever value that method returns.
-1 if the end of the
stream is reached.
read
public int read(byte b[]) throws IOException
byte.length bytes of data from this
input stream into an array of bytes. This method blocks until some
input is available.
The read method of FilterInputStream
calls the read method of three arguments with the
arguments b, 0, and
b.length, and returns whatever value that method returns.
Note that this method does not call the one-argument
read method of its underlying stream with the single
argument b. Subclasses of
FilterInputStream do not need to override this method
if they have overridden the three-argument read method.
-1 if there is no more data because the end of
the stream has been reached.
read
public int read(byte b[],
int off,
int len) throws IOException
len bytes of data from this input stream
into an array of bytes. This method blocks until some input is
available.
The read method of FilterInputStream
calls the read method of its underlying input stream
with the same arguments and returns whatever value that method returns.
-1 if there is no more data because the end of
the stream has been reached.
skip
public long skip(long n) throws IOException
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.
The skip method of FilterInputStream
calls the skip method of its underlying input stream
with the same argument, and returns whatever value that method does.
available
public int available() throws IOException
The available method of
FilterInputStream calls the available
method of its underlying input stream and returns whatever value
that method returns.
close
public void close() throws IOException
close method of
FilterInputStream calls the close method
of its underlying input stream.
mark
public synchronized void mark(int readlimit)
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.
The mark method of FilterInputStream
calls the mark method of its underlying input stream
with the readlimit argument.
reset
public synchronized void reset() throws IOException
mark method was last called on this input stream.
The reset method of FilterInputStream
calls the reset method of its underlying input stream.
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.
markSupported
public boolean markSupported()
mark
and reset methods. The markSupported
method of FilterInputStream calls the
markSupported method of its underlying input stream
and returns whatever value that method returns.
true if this stream type supports the
mark and reset method;
false otherwise.
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