public class FilterInputStream extends InputStream
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.| Modifier and Type | Field and Description |
|---|---|
protected InputStream |
in
The input stream to be filtered.
|
| Modifier | Constructor and Description |
|---|---|
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. |
| Modifier and Type | Method and Description |
|---|---|
int |
available()
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.
|
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()
Tests if this input stream supports the
mark
and reset methods. |
int |
read()
Reads the next byte of data from this input stream.
|
int |
read(byte[] b)
Reads up to
byte.length bytes of data from this
input stream into an array of bytes. |
int |
read(byte[] b,
int off,
int len)
Reads up to
len bytes of data from this 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. |
long |
skip(long n)
Skips over and discards
n bytes of data from the
input stream. |
protected volatile InputStream in
protected FilterInputStream(InputStream in)
FilterInputStream
by assigning the argument in
to the field this.in so as
to remember it for later use.in - the underlying input stream, or null if
this instance is to be created without an underlying stream.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.
This method
simply performs in.read() and returns the result.
read in class InputStream-1 if the end of the
stream is reached.IOException - if an I/O error occurs.inpublic 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.
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.
read in class InputStreamb - 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)public int read(byte[] b,
int off,
int len)
throws IOException
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.
read in class InputStreamb - 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.NullPointerException - If b is null.IndexOutOfBoundsException - If off is negative,
len is negative, or len is greater than
b.length - offIOException - if an I/O error occurs.inpublic 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.
This method simply performs in.skip(n).
skip in class InputStreamn - the number of bytes to be skipped.IOException - if the stream does not support seek,
or if some other I/O error occurs.public int available()
throws IOException
This method returns the result of in.available().
available in class InputStreamIOException - if an I/O error occurs.public void close()
throws IOException
in.close().close in interface Closeableclose in interface AutoCloseableclose in class InputStreamIOException - if an I/O error occurs.inpublic 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.
This method simply performs in.mark(readlimit).
mark in class InputStreamreadlimit - the maximum limit of bytes that can be read before
the mark position becomes invalid.in,
reset()public void reset()
throws IOException
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.
reset in class InputStreamIOException - if the stream has not been marked or if the
mark has been invalidated.in,
mark(int)public boolean markSupported()
mark
and reset methods.
This method
simply performs in.markSupported().markSupported in class InputStreamtrue if this stream type supports the
mark and reset method;
false otherwise.in,
InputStream.mark(int),
InputStream.reset() Submit a bug or feature
For further API reference and developer documentation, see Java SE Documentation. That documentation contains more detailed, developer-targeted descriptions, with conceptual overviews, definitions of terms, workarounds, and working code examples.
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