- java.lang.Object
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- java.io.InputStream
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- java.io.FilterInputStream
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- All Implemented Interfaces:
Closeable,AutoCloseable
- Direct Known Subclasses:
BufferedInputStream,CheckedInputStream,CipherInputStream,DataInputStream,DeflaterInputStream,DigestInputStream,InflaterInputStream,LineNumberInputStream,ProgressMonitorInputStream,PushbackInputStream
public class FilterInputStream extends InputStream
AFilterInputStreamcontains 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 classFilterInputStreamitself simply overrides all methods ofInputStreamwith versions that pass all requests to the contained input stream. Subclasses ofFilterInputStreammay further override some of these methods and may also provide additional methods and fields.- Since:
- 1.0
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Field Summary
Fields Modifier and Type Field Description protected InputStreaminThe input stream to be filtered.
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Constructor Summary
Constructors Modifier Constructor Description protectedFilterInputStream(InputStream in)Creates aFilterInputStreamby assigning the argumentinto the fieldthis.inso as to remember it for later use.
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description intavailable()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.voidclose()Closes this input stream and releases any system resources associated with the stream.voidmark(int readlimit)Marks the current position in this input stream.booleanmarkSupported()Tests if this input stream supports themarkandresetmethods.intread()Reads the next byte of data from this input stream.intread(byte[] b)Reads up tob.lengthbytes of data from this input stream into an array of bytes.intread(byte[] b, int off, int len)Reads up tolenbytes of data from this input stream into an array of bytes.voidreset()Repositions this stream to the position at the time themarkmethod was last called on this input stream.longskip(long n)Skips over and discardsnbytes of data from the input stream.-
Methods declared in class java.io.InputStream
nullInputStream, readAllBytes, readNBytes, readNBytes, transferTo
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Field Detail
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in
protected volatile InputStream in
The input stream to be filtered.
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Constructor Detail
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FilterInputStream
protected FilterInputStream(InputStream in)
Creates aFilterInputStreamby assigning the argumentinto the fieldthis.inso as to remember it for later use.- Parameters:
in- the underlying input stream, ornullif this instance is to be created without an underlying stream.
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Method Detail
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read
public int read() throws IOExceptionReads the next byte of data from this input stream. The value byte is returned as anintin the range0to255. If no byte is available because the end of the stream has been reached, the value-1is 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.- Specified by:
readin classInputStream- Returns:
- the next byte of data, or
-1if the end of the stream is reached. - Throws:
IOException- if an I/O error occurs.- See Also:
in
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read
public int read(byte[] b) throws IOExceptionReads up tob.lengthbytes 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 doin.read(b)instead; certain subclasses ofFilterInputStreamdepend on the implementation strategy actually used.- Overrides:
readin classInputStream- Parameters:
b- the buffer into which the data is read.- Returns:
- the total number of bytes read into the buffer, or
-1if 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(byte[], int, int)
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read
public int read(byte[] b, int off, int len) throws IOExceptionReads up tolenbytes of data from this input stream into an array of bytes. Iflenis not zero, the method blocks until some input is available; otherwise, no bytes are read and0is returned.This method simply performs
in.read(b, off, len)and returns the result.- Overrides:
readin classInputStream- Parameters:
b- the buffer into which the data is read.off- the start offset in the destination arrayblen- the maximum number of bytes read.- Returns:
- the total number of bytes read into the buffer, or
-1if there is no more data because the end of the stream has been reached. - Throws:
NullPointerException- Ifbisnull.IndexOutOfBoundsException- Ifoffis negative,lenis negative, orlenis greater thanb.length - offIOException- if an I/O error occurs.- See Also:
in
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skip
public long skip(long n) throws IOExceptionSkips over and discardsnbytes of data from the input stream. Theskipmethod may, for a variety of reasons, end up skipping over some smaller number of bytes, possibly0. The actual number of bytes skipped is returned.This method simply performs
in.skip(n).- Overrides:
skipin classInputStream- Parameters:
n- the number of bytes to be skipped.- Returns:
- the actual number of bytes skipped.
- Throws:
IOException- ifin.skip(n)throws an IOException.
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available
public int available() throws IOExceptionReturns 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.This method returns the result of
in.available().- Overrides:
availablein classInputStream- 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.
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close
public void close() throws IOExceptionCloses this input stream and releases any system resources associated with the stream. This method simply performsin.close().- Specified by:
closein interfaceAutoCloseable- Specified by:
closein interfaceCloseable- Overrides:
closein classInputStream- Throws:
IOException- if an I/O error occurs.- See Also:
in
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mark
public void mark(int readlimit)
Marks the current position in this input stream. A subsequent call to theresetmethod repositions this stream at the last marked position so that subsequent reads re-read the same bytes.The
readlimitargument 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).- Overrides:
markin classInputStream- Parameters:
readlimit- the maximum limit of bytes that can be read before the mark position becomes invalid.- See Also:
in,reset()
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reset
public void reset() throws IOExceptionRepositions this stream to the position at the time themarkmethod 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.
- Overrides:
resetin classInputStream- Throws:
IOException- if the stream has not been marked or if the mark has been invalidated.- See Also:
in,mark(int)
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markSupported
public boolean markSupported()
Tests if this input stream supports themarkandresetmethods. This method simply performsin.markSupported().- Overrides:
markSupportedin classInputStream- Returns:
trueif this stream type supports themarkandresetmethod;falseotherwise.- See Also:
in,InputStream.mark(int),InputStream.reset()
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