Class BufferedInputStream
- java.lang.Object
-
- java.io.InputStream
-
- java.io.FilterInputStream
-
- java.io.BufferedInputStream
- All Implemented Interfaces:
-
Closeable
,AutoCloseable
public class BufferedInputStream extends FilterInputStream
A 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 Type | Field | Description |
---|---|---|
protected byte[] | buf | The internal buffer array where the data is stored. |
protected int | count | The index one greater than the index of the last valid byte in the buffer. |
protected int | marklimit | The maximum read ahead allowed after a call to the |
protected int | markpos | The value of the |
protected int | pos | The current position in the buffer. |
Fields declared in class java.io.FilterInputStream
in
Constructor Summary
Constructor | Description |
---|---|
BufferedInputStream(InputStream in) | Creates a |
BufferedInputStream(InputStream in,
int size) | Creates a |
Method Summary
Modifier and Type | Method | 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 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 the |
boolean | markSupported() | Tests if this input stream supports the |
int | read() | See the general contract of the |
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 the |
long | skip(long n) | See the general contract of the |
Methods declared in class java.io.FilterInputStream
read
Methods declared in class java.io.InputStream
nullInputStream, readAllBytes, readNBytes, readNBytes, transferTo
Methods declared in class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
Field Detail
buf
protected volatile byte[] buf
The internal buffer array where the data is stored. When necessary, it may be replaced by another array of a different size.
count
protected int count
The index one greater than the index of the last valid byte in the buffer. This value is always in the range 0
through buf.length
; elements buf[0]
through buf[count-1]
contain buffered input data obtained from the underlying input stream.
pos
protected int pos
The current position in the buffer. This is the index of the next character to be read from the buf
array.
This value is always in the range 0
through count
. If it is less than count
, then buf[pos]
is the next byte to be supplied as input; if it is equal to count
, then the next read
or skip
operation will require more bytes to be read from the contained input stream.
- See Also:
buf
markpos
protected int markpos
The value of the pos
field at the time the last mark
method was called.
This value is always in the range -1
through pos
. If there is no marked position in the input stream, this field is -1
. If there is a marked position in the input stream, then buf[markpos]
is the first byte to be supplied as input after a reset
operation. If markpos
is not -1
, then all bytes from positions buf[markpos]
through buf[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 of count
, pos
, and markpos
); they may not be discarded unless and until the difference between pos
and markpos
exceeds marklimit
.
marklimit
protected int marklimit
The maximum read ahead allowed after a call to the mark
method before subsequent calls to the reset
method fail. Whenever the difference between pos
and markpos
exceeds marklimit
, then the mark may be dropped by setting markpos
to -1
.
Constructor Detail
BufferedInputStream
public BufferedInputStream(InputStream in)
Creates a BufferedInputStream
and saves its argument, the input stream in
, for later use. An internal buffer array is created and stored in buf
.
- Parameters:
-
in
- the underlying input stream.
BufferedInputStream
public BufferedInputStream(InputStream in, int size)
Creates a BufferedInputStream
with the specified buffer size, and saves its argument, the input stream in
, for later use. An internal buffer array of length size
is created and stored in buf
.
- Parameters:
-
in
- the underlying input stream. -
size
- the buffer size. - Throws:
-
IllegalArgumentException
- ifsize <= 0
.
Method Detail
read
public int read() throws IOException
See the general contract of the read
method of InputStream
.
- 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:
FilterInputStream.in
read
public int read(byte[] b, int off, int len) throws IOException
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
method of the read
class. As an additional convenience, it attempts to read as many bytes as possible by repeatedly invoking the InputStream
read
method of the underlying stream. This iterated read
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. - See Also:
FilterInputStream.in
skip
public long skip(long n) throws IOException
See the general contract of the skip
method of InputStream
.
- 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.
available
public int available() throws IOException
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 the in
.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 the mark
method of InputStream
.
- Overrides:
-
mark
in classFilterInputStream
- Parameters:
-
readlimit
- the maximum limit of bytes that can be read before the mark position becomes invalid. - See Also:
reset()
reset
public void reset() throws IOException
See the general contract of the reset
method of InputStream
.
If markpos
is -1
(no mark has been set or the mark has been invalidated), an IOException
is thrown. Otherwise, pos
is set equal to markpos
.
- 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:
mark(int)
markSupported
public boolean markSupported()
Tests if this input stream supports the mark
and reset
methods. The markSupported
method of BufferedInputStream
returns true
.
- Overrides:
-
markSupported
in classFilterInputStream
- Returns:
- a
boolean
indicating if this stream type supports themark
andreset
methods. - See Also:
-
InputStream.mark(int)
,InputStream.reset()
close
public void close() throws IOException
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:
FilterInputStream.in