Java IO.pdf - Nguyen Dang Binh

Java I/O
Each inflater input stream uses a protected Inflater object called inf to decompress data
that is stored in a protected internal byte array called buf. There's also a protected int field
called len that (unreliably) stores the number of bytes currently in the buffer, as opposed to
the length of the buffer itself.
protected Inflater inf;
protected byte[] buf;
protected int len;
The same Inflater object must not be used in multiple streams at the same time.
The underlying input stream from which deflated data is read, the Inflater object inf, and
the length of the byte array buf are all set by one of the three InflaterInputStream()
constructors:
public InflaterInputStream(InputStream in, Inflater inf, int bufferLength)
public InflaterInputStream(InputStream in, Inflater inf)
public InflaterInputStream(InputStream in)
The underlying input stream must be specified, while the buffer length defaults to 512 bytes,
and the Inflater defaults to an inflater for deflated streams (as opposed to zipped or gzipped
streams). Of course, the InflaterInputStream has all the usual input stream methods like
read(), available(), and close(). It overrides the following three methods:
public int read() throws IOException
public int read(byte[] data, int offset, int length) throws IOException
public long skip(long n) throws IOException
For the most part, you use these the same way you'd use any read() or skip() method.
However, it's occasionally useful to know that the read method throws a new subclass of
IOException, java.util.zip.ZipException, if the problem is that the data doesn't adhere
to the expected format. You should also know that read(), skip(), and all other input stream
methods count the uncompressed bytes, not the compressed raw bytes that were actually read.
There's also one new protected method, fill(), which reads compressed data from the
underlying input stream into buf, sets len to the number of bytes read, and then sets inf's
input to the appropriate subarray of buf:
protected void fill() throws IOException
Example 9.4 is a simple character-mode program that inflates files. When it is combined with
Example 9.3, you've now got a simple compression system. Filenames are read from the
command line. A file input stream is opened from each file that ends in .df l, and this stream is
chained to an inflater input stream. A file output stream is opened to that same file minus the
.dfl extension. Finally, a stream copier pours the data from the input file through the inflating
stream into the output file.
Example 9.4. The FileInflater Program
import java.io.*;
import java.util.zip.*;
import com.macfaq.io.*;
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