Java IO.pdf - Nguyen Dang Binh

Java I/O
A file input stream named fin is opened to each file. At the same time, a file output stream
named fout is opened to an output file with the same name plus the three-letter extension .dfl.
The program then enters a loop in which it tries to read 1024 -byte chunks of data from fin,
though care is taken not to assume that 1024 bytes are actually read. Any data that is
successfully read is passed to the deflater's setInput() method. The data is repeatedly
deflated and written onto the output stream until the deflater indicates that it needs more
input. Then the process repeats itself until the end of the input stream is reached. When no
more input is available, the deflater's finish() method is called. Then the deflater's
deflate() method is repeatedly invoked until its finished() method returns true. At this
point, the program breaks out of the infinite read() loop and moves on to the next file.
Figure 9.2 is a flow chart demonstrating this sequence for a single file. One thing may seem
a little fishy about this chart. After the deflater is finished, a repeated check is made to see if
the deflater is in fact finished. The finish() method tells the deflater that no more data is
forthcoming and it should work with whatever data remains in its input buffer. However,
the finished() method does not actually return true until the input buffer has been emptied
by calls to deflate().
Figure 9.2. The deflation sequence
Example 9.1. The DirectDeflater
import java.io.*;
import java.util.zip.*;
146