Bufferedinputstream java что это

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.

Field Summary

The maximum read ahead allowed after a call to the mark method before subsequent calls to the reset method fail.

Fields declared in class java.io.FilterInputStream

Constructor Summary

Creates a BufferedInputStream with the specified buffer size, and saves its argument, the input stream in , for later use.

Method Summary

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.

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Methods declared in class java.io.FilterInputStream

Methods declared in class java.io.InputStream

Methods declared in class java.lang.Object

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

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

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.

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

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

Creates a BufferedInputStream and saves its argument, the input stream in , for later use. An internal buffer array is created and stored in buf .

BufferedInputStream

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 .

Method Detail

read

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.

Subclasses of this class are encouraged, but not required, to attempt to read as many bytes as possible in the same fashion.

skip

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 the in .available().

mark

public void mark(int readlimit)

reset

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 .

markSupported

public boolean markSupported()

Tests if this input stream supports the mark and reset methods. The markSupported method of BufferedInputStream returns true .

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.

Report a bug or suggest an enhancement
For further API reference and developer documentation see the Java SE Documentation, which contains more detailed, developer-targeted descriptions with conceptual overviews, definitions of terms, workarounds, and working code examples.
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