程序包 java.io

类 FilterInputStream

java.lang.Object

java.io.InputStream

java.io.FilterInputStream

所有已实现的接口:

Closeable, AutoCloseable

直接已知子类:

BufferedInputStream, CheckedInputStream, CipherInputStream, DataInputStream, DeflaterInputStream, DigestInputStream, InflaterInputStream, LineNumberInputStream, PushbackInputStream

public class FilterInputStream
extends InputStream

A 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.

从以下版本开始:

JDK1.0

字段概要

字段

限定符和类型	字段	说明
protected InputStream	in	The input stream to be filtered.

构造器概要

构造器

限定符	构造器	说明
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.

方法概要

限定符和类型	方法	说明
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.

从类继承的方法 java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

字段详细资料

in

protected volatile InputStream in

The input stream to be filtered.

构造器详细资料

FilterInputStream

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.

参数:

in - the underlying input stream, or null if this instance is to be created without an underlying stream.

方法详细资料

read

public int read()
         throws IOException

Reads the next byte of data from this input stream. The value byte is returned as an 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.

指定者:

read 在类中 InputStream

返回:

the next byte of data, or -1 if the end of the stream is reached.

抛出:

IOException - if an I/O error occurs.

另请参阅:

in

read

public int read(byte[] b)
         throws IOException

Reads up to 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.

覆盖:

read 在类中 InputStream

参数:

b - the buffer into which the data is read.

返回:

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.

抛出:

IOException - if an I/O error occurs.

另请参阅:

read(byte[], int, int)

read

public int read(byte[] b,
                int off,
                int len)
         throws IOException

Reads up to 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.

覆盖:

read 在类中 InputStream

参数:

b - the buffer into which the data is read.

off - the start offset in the destination array b

len - the maximum number of bytes read.

返回:

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.

抛出:

NullPointerException - If b is null.

IndexOutOfBoundsException - If off is negative, len is negative, or len is greater than b.length - off

IOException - if an I/O error occurs.

另请参阅:

in

skip

public long skip(long n)
          throws IOException

Skips over and discards 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).

覆盖:

skip 在类中 InputStream

参数:

n - the number of bytes to be skipped.

返回:

the actual number of bytes skipped.

抛出:

IOException - if the stream does not support seek, or if some other 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 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().

覆盖:

available 在类中 InputStream

返回:

an estimate of the number of bytes that can be read (or skipped over) from this input stream without blocking.

抛出:

IOException - if an I/O error occurs.

close

public void close()
           throws IOException

Closes this input stream and releases any system resources associated with the stream. This method simply performs in.close().

指定者:

close 在接口中 AutoCloseable

指定者:

close 在接口中 Closeable

覆盖:

close 在类中 InputStream

抛出:

IOException - if an I/O error occurs.

另请参阅:

in

mark

public void mark(int readlimit)

Marks the current position in this input stream. A subsequent call to the 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).

覆盖:

mark 在类中 InputStream

参数:

readlimit - the maximum limit of bytes that can be read before the mark position becomes invalid.

另请参阅:

in, reset()

reset

public void reset()
           throws IOException

Repositions this stream to the position at the time the 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.

覆盖:

reset 在类中 InputStream

抛出:

IOException - if the stream has not been marked or if the mark has been invalidated.

另请参阅:

in, mark(int)

markSupported

public boolean markSupported()

Tests if this input stream supports the mark and reset methods. This method simply performs in.markSupported().

覆盖:

markSupported 在类中 InputStream

返回:

true if this stream type supports the mark and reset method; false otherwise.

另请参阅:

in, InputStream.mark(int), InputStream.reset()