Class BufferedInputStream
- All Implemented Interfaces:
Closeable
,AutoCloseable
BufferedInputStream
adds
functionality to another input stream-namely,
the ability to buffer the input and to
support the mark
and reset
methods. When the BufferedInputStream
is created, an internal buffer array is
created. As bytes from the stream are read
or skipped, the internal buffer is refilled
as necessary from the contained input stream,
many bytes at a time. The mark
operation remembers a point in the input
stream and the reset
operation
causes all the bytes read since the most
recent mark
operation to be
reread before new bytes are taken from
the contained input stream.- Since:
- 1.0
-
Field Summary
Modifier and TypeFieldDescriptionprotected byte[]
The internal buffer array where the data is stored.protected int
The index one greater than the index of the last valid byte in the buffer.protected int
The maximum read ahead allowed after a call to themark
method before subsequent calls to thereset
method fail.protected int
The value of thepos
field at the time the lastmark
method was called.protected int
The current position in the buffer.Fields declared in class java.io.FilterInputStream
in
-
Constructor Summary
ConstructorDescriptionCreates aBufferedInputStream
and saves its argument, the input streamin
, for later use.BufferedInputStream
(InputStream in, int size) Creates aBufferedInputStream
with the specified buffer size, and saves its argument, the input streamin
, for later use. -
Method Summary
Modifier and TypeMethodDescriptionint
Returns an estimate of the number of bytes that can be read (or skipped over) from this input stream without blocking by the next invocation 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) See the general contract of themark
method ofInputStream
.boolean
Tests if this input stream supports themark
andreset
methods.int
read()
See the general contract of theread
method ofInputStream
.int
read
(byte[] b, int off, int len) Reads bytes from this byte-input stream into the specified byte array, starting at the given offset.void
reset()
See the general contract of thereset
method ofInputStream
.long
skip
(long n) See the general contract of theskip
method ofInputStream
.Methods declared in class java.io.FilterInputStream
read
Methods declared in class java.io.InputStream
nullInputStream, readAllBytes, readNBytes, readNBytes, skipNBytes, transferTo
-
Field Details
-
buf
protected volatile byte[] bufThe internal buffer array where the data is stored. When necessary, it may be replaced by another array of a different size. -
count
protected int countThe index one greater than the index of the last valid byte in the buffer. This value is always in the range0
throughbuf.length
; elementsbuf[0]
throughbuf[count-1]
contain buffered input data obtained from the underlying input stream. -
pos
protected int posThe current position in the buffer. This is the index of the next byte to be read from thebuf
array.This value is always in the range
0
throughcount
. If it is less thancount
, thenbuf[pos]
is the next byte to be supplied as input; if it is equal tocount
, then the nextread
orskip
operation will require more bytes to be read from the contained input stream.- See Also:
-
markpos
protected int markposThe value of thepos
field at the time the lastmark
method was called.This value is always in the range
-1
throughpos
. If there is no marked position in the input stream, this field is-1
. If there is a marked position in the input stream, thenbuf[markpos]
is the first byte to be supplied as input after areset
operation. Ifmarkpos
is not-1
, then all bytes from positionsbuf[markpos]
throughbuf[pos-1]
must remain in the buffer array (though they may be moved to another place in the buffer array, with suitable adjustments to the values ofcount
,pos
, andmarkpos
); they may not be discarded unless and until the difference betweenpos
andmarkpos
exceedsmarklimit
.- See Also:
-
marklimit
protected int marklimitThe maximum read ahead allowed after a call to themark
method before subsequent calls to thereset
method fail. Whenever the difference betweenpos
andmarkpos
exceedsmarklimit
, then the mark may be dropped by settingmarkpos
to-1
.- See Also:
-
-
Constructor Details
-
BufferedInputStream
Creates aBufferedInputStream
and saves its argument, the input streamin
, for later use. An internal buffer array is created and stored inbuf
.- Parameters:
in
- the underlying input stream.
-
BufferedInputStream
Creates aBufferedInputStream
with the specified buffer size, and saves its argument, the input streamin
, for later use. An internal buffer array of lengthsize
is created and stored inbuf
.- Parameters:
in
- the underlying input stream.size
- the buffer size.- Throws:
IllegalArgumentException
- ifsize <= 0
.
-
-
Method Details
-
read
See the general contract of theread
method ofInputStream
.- Overrides:
read
in classFilterInputStream
- Returns:
- the next byte of data, or
-1
if the end of the stream is reached. - Throws:
IOException
- if this input stream has been closed by invoking itsclose()
method, or an I/O error occurs.- See Also:
-
read
Reads bytes from this byte-input stream into the specified byte array, starting at the given offset.This method implements the general contract of the corresponding
read
method of theInputStream
class. As an additional convenience, it attempts to read as many bytes as possible by repeatedly invoking theread
method of the underlying stream. This iteratedread
continues until one of the following conditions becomes true:- The specified number of bytes have been read,
- The
read
method of the underlying stream returns-1
, indicating end-of-file, or - The
available
method of the underlying stream returns zero, indicating that further input requests would block.
read
on the underlying stream returns-1
to indicate end-of-file then this method returns-1
. Otherwise, this method returns the number of bytes actually read.Subclasses of this class are encouraged, but not required, to attempt to read as many bytes as possible in the same fashion.
- Overrides:
read
in classFilterInputStream
- Parameters:
b
- destination buffer.off
- offset at which to start storing bytes.len
- maximum number of bytes to read.- Returns:
- the number of bytes read, or
-1
if the end of the stream has been reached. - Throws:
IOException
- if this input stream has been closed by invoking itsclose()
method, or an I/O error occurs.IndexOutOfBoundsException
- Ifoff
is negative,len
is negative, orlen
is greater thanb.length - off
- See Also:
-
skip
See the general contract of theskip
method ofInputStream
.- Overrides:
skip
in classFilterInputStream
- Parameters:
n
- the number of bytes to be skipped.- Returns:
- the actual number of bytes skipped.
- Throws:
IOException
- if this input stream has been closed by invoking itsclose()
method,in.skip(n)
throws an IOException, or an I/O error occurs.- See Also:
-
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 invocation of a method for this input stream. The next invocation 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 sum of the number of bytes remaining to be read in the buffer (
count - pos
) and the result of calling thein
.available()
.- Overrides:
available
in classFilterInputStream
- Returns:
- an estimate of the number of bytes that can be read (or skipped over) from this input stream without blocking.
- Throws:
IOException
- if this input stream has been closed by invoking itsclose()
method, or an I/O error occurs.
-
mark
public void mark(int readlimit) See the general contract of themark
method ofInputStream
.- Overrides:
mark
in classFilterInputStream
- Parameters:
readlimit
- the maximum limit of bytes that can be read before the mark position becomes invalid.- See Also:
-
reset
See the general contract of thereset
method ofInputStream
.If
markpos
is-1
(no mark has been set or the mark has been invalidated), anIOException
is thrown. Otherwise,pos
is set equal tomarkpos
.- Overrides:
reset
in classFilterInputStream
- Throws:
IOException
- if this stream has not been marked or, if the mark has been invalidated, or the stream has been closed by invoking itsclose()
method, or an I/O error occurs.- See Also:
-
markSupported
public boolean markSupported()Tests if this input stream supports themark
andreset
methods. ThemarkSupported
method ofBufferedInputStream
returnstrue
.- Overrides:
markSupported
in classFilterInputStream
- Returns:
- a
boolean
indicating if this stream type supports themark
andreset
methods. - See Also:
-
close
Closes this input stream and releases any system resources associated with the stream. Once the stream has been closed, further read(), available(), reset(), or skip() invocations will throw an IOException. Closing a previously closed stream has no effect.- Specified by:
close
in interfaceAutoCloseable
- Specified by:
close
in interfaceCloseable
- Overrides:
close
in classFilterInputStream
- Throws:
IOException
- if an I/O error occurs.- See Also:
-