question: public synchronized int write ( InputStream in ) throws IOException { int readCount = 0 ; int inBufferPos = count - filledBufferSum ; int n = in . read ( currentBuffer , inBufferPos , currentBuffer . length - inBufferPos ) ; while ( n != - 1 ) { readCount += n ; inBufferPos += n ; count += n ; if ( inBufferPos == currentBuffer . length ) { needNewBuffer ( currentBuffer . length ) ; inBufferPos = 0 ; } n = in . read ( currentBuffer , inBufferPos , currentBuffer . length - inBufferPos ) ; } return readCount ; }
target:  Writes the entire contents of the specified input stream to this byte stream. Bytes from the input stream are read directly into the internal buffers of this streams.