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. |
@Nullable protected volatile InputStream in
protected FilterInputStream(@Nullable 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 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 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()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 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 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.