Class FilterInputStream
java.lang.Object
java.io.InputStream
java.io.FilterInputStream
- All Implemented Interfaces:
Closeable
,AutoCloseable
- Direct Known Subclasses:
BufferedInputStream
,CheckedInputStream
,CipherInputStream
,DataInputStream
,DeflaterInputStream
,DigestInputStream
,InflaterInputStream
,LineNumberInputStream
,ProgressMonitorInputStream
,PushbackInputStream
A
FilterInputStream
wraps 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 select methods of InputStream
with versions
that pass all requests to the wrapped input stream. Subclasses of
FilterInputStream
may of course override any methods declared or
inherited by FilterInputStream
, and may also provide additional
fields and methods.- Since:
- 1.0
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Field Summary
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Constructor Summary
ModifierConstructorDescriptionprotected
Creates aFilterInputStream
by assigning the argumentin
to the fieldthis.in
so as to remember it 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 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
Tests if this input stream supports themark
andreset
methods.int
read()
Reads the next byte of data from the input stream.int
read
(byte[] b) Reads up tob.length
bytes of data from this input stream into an array of bytes.int
read
(byte[] b, int off, int len) Reads up tolen
bytes of data from this input stream into an array of bytes.void
reset()
Repositions this stream to the position at the time themark
method was last called on this input stream.long
skip
(long n) Skips over and discardsn
bytes of data from the input stream.Methods inherited from class java.io.InputStream
nullInputStream, readAllBytes, readNBytes, readNBytes, skipNBytes, transferTo
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Field Details
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in
The input stream to be filtered.
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-
Constructor Details
-
FilterInputStream
Creates aFilterInputStream
by assigning the argumentin
to the fieldthis.in
so as to remember it for later use.- Parameters:
in
- the underlying input stream, ornull
if this instance is to be created without an underlying stream.
-
-
Method Details
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read
Reads the next byte of data from the input stream. The value byte is returned as anint
in the range0
to255
. 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.- Specified by:
read
in classInputStream
- Implementation Requirements:
- This method simply performs
in.read()
and returns the result. - Returns:
- the next byte of data, or
-1
if the end of the stream is reached. - Throws:
IOException
- if an I/O error occurs.- See Also:
-
read
Reads up tob.length
bytes of data from this input stream into an array of bytes. This method blocks until some input is available.- Overrides:
read
in classInputStream
- Implementation Requirements:
- This method simply performs the call
read(b, 0, b.length)
and returns the result. It is important that it does not doin.read(b)
instead; certain subclasses ofFilterInputStream
depend on the implementation strategy actually used. - Parameters:
b
- the buffer into which the data is read.- Returns:
- the total number of bytes read into the buffer, or
-1
if there is no more data because the end of the stream has been reached. - Throws:
IOException
- if an I/O error occurs.- See Also:
-
read
Reads up tolen
bytes of data from this input stream into an array of bytes. Iflen
is not zero, the method blocks until some input is available; otherwise, no bytes are read and0
is returned.- Overrides:
read
in classInputStream
- Implementation Requirements:
- This method simply performs
in.read(b, off, len)
and returns the result. - Parameters:
b
- the buffer into which the data is read.off
- the start offset in arrayb
at which the data is written.len
- the maximum number of bytes to read.- Returns:
- the total number of bytes read into the buffer, or
-1
if there is no more data because the end of the stream has been reached. - Throws:
NullPointerException
- Ifb
isnull
.IndexOutOfBoundsException
- Ifoff
is negative,len
is negative, orlen
is greater thanb.length - off
IOException
- if an I/O error occurs.- See Also:
-
skip
Skips over and discardsn
bytes of data from the input stream. Theskip
method may, for a variety of reasons, end up skipping over some smaller number of bytes, possibly0
. The actual number of bytes skipped is returned.- Overrides:
skip
in classInputStream
- Implementation Requirements:
- This method simply performs
in.skip(n)
and returns the result. - Parameters:
n
- the number of bytes to be skipped.- Returns:
- the actual number of bytes skipped.
- Throws:
IOException
- ifin.skip(n)
throws an IOException.- 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 caller of a method for this input stream. The next caller 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.- Overrides:
available
in classInputStream
- Implementation Requirements:
- This method returns the result of
in.available()
. - Returns:
- an estimate of the number of bytes that can be read (or skipped over) from this input stream without blocking.
- Throws:
IOException
- if an I/O error occurs.
-
close
Closes this input stream and releases any system resources associated with the stream.- Specified by:
close
in interfaceAutoCloseable
- Specified by:
close
in interfaceCloseable
- Overrides:
close
in classInputStream
- Implementation Requirements:
- This method simply performs
in.close()
. - Throws:
IOException
- if an I/O error occurs.- See Also:
-
mark
public void mark(int readlimit) Marks the current position in this input stream. A subsequent call to thereset
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.- Overrides:
mark
in classInputStream
- Implementation Requirements:
- This method simply performs
in.mark(readlimit)
. - Parameters:
readlimit
- the maximum limit of bytes that can be read before the mark position becomes invalid.- See Also:
-
reset
Repositions this stream to the position at the time themark
method was last called on this 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.
- Overrides:
reset
in classInputStream
- Implementation Requirements:
- This method simply performs
in.reset()
. - Throws:
IOException
- if this stream has not been marked or if the mark has been invalidated.- See Also:
-
markSupported
public boolean markSupported()Tests if this input stream supports themark
andreset
methods.- Overrides:
markSupported
in classInputStream
- Implementation Requirements:
- This method simply performs
in.markSupported()
. - Returns:
true
if this stream type supports themark
andreset
method;false
otherwise.- See Also:
-