Java IO.pdf - Nguyen Dang Binh

9.1.2.7 An example
Java I/O
Example 9.2 is a simple program that inflates files named on the command line. First an
Inflater object, inf, is created. 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
minus the three-letter extension .df l. 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 inflater's setInput()
method. This data is repeatedly inflated and written onto the output stream until the inflater
indicates that it needs more input. Then the process repeats itself until the end of the input
stream is reached and the inflater's finished() method returns true. At this point, the
program breaks out of the read() loop and moves on to the next file.
Example 9.2. The DirectInflater
import java.io.*;
import java.util.zip.*;
public class DirectInflater {
public static void main(String[] args) {
Inflater inf = new Inflater();
byte[] input = new byte[1024];
byte[] output = new byte[1024];
for (int i = 0; i < args.length; i++) {
try {
if (!args[i].endsWith(DirectDeflater.DEFLATE_SUFFIX)) {
System.err.println(args[i] + " does not look like a deflated
file");
continue;
}
FileInputStream fin = new FileInputStream(args[i]);
FileOutputStream fout = new FileOutputStream(args[i].substring(0,
args[i].length() - DirectDeflater.DEFLATE_SUFFIX.length()));
while (true) { // Read and inflate the data.
// Fill the input array.
int numRead = fin.read(input);
if (numRead != -1) { // End of stream, finish inflating.
inf.setInput(input, 0, numRead);
} // end if
// Inflate the input.
int numDecompressed = 0;
while ((numDecompressed = inf.inflate(output, 0, output.length))
!= 0) {
fout.write(output, 0, numDecompressed);
}
// At this point inflate() has returned 0.
// Let's find out why.
if (inf.finished()) { // all done
break;
}
else if (inf.needsDictionary()) { //We don't handle dictionaries.
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