Mega Code Archive
Gzipping files and zipping directories
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/*
* Copyright (c) 2004 David Flanagan. All rights reserved.
* This code is from the book Java Examples in a Nutshell, 3nd Edition.
* It is provided AS-IS, WITHOUT ANY WARRANTY either expressed or implied.
* You may study, use, and modify it for any non-commercial purpose,
* including teaching and use in open-source projects.
* You may distribute it non-commercially as long as you retain this notice.
* For a commercial use license, or to purchase the book,
* please visit http://www.davidflanagan.com/javaexamples3.
*/
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.zip.GZIPOutputStream;
import java.util.zip.ZipEntry;
import java.util.zip.ZipOutputStream;
/**
* This class defines two static methods for gzipping files and zipping
* directories. It also defines a demonstration program as a nested class.
*/
public class Compress {
/** Gzip the contents of the from file and save in the to file. */
public static void gzipFile(String from, String to) throws IOException {
// Create stream to read from the from file
FileInputStream in = new FileInputStream(from);
// Create stream to compress data and write it to the to file.
GZIPOutputStream out = new GZIPOutputStream(new FileOutputStream(to));
// Copy bytes from one stream to the other
byte[] buffer = new byte[4096];
int bytes_read;
while ((bytes_read = in.read(buffer)) != -1)
out.write(buffer, 0, bytes_read);
// And close the streams
in.close();
out.close();
}
/** Zip the contents of the directory, and save it in the zipfile */
public static void zipDirectory(String dir, String zipfile) throws IOException,
IllegalArgumentException {
// Check that the directory is a directory, and get its contents
File d = new File(dir);
if (!d.isDirectory())
throw new IllegalArgumentException("Compress: not a directory: " + dir);
String[] entries = d.list();
byte[] buffer = new byte[4096]; // Create a buffer for copying
int bytes_read;
// Create a stream to compress data and write it to the zipfile
ZipOutputStream out = new ZipOutputStream(new FileOutputStream(zipfile));
// Loop through all entries in the directory
for (int i = 0; i < entries.length; i++) {
File f = new File(d, entries[i]);
if (f.isDirectory())
continue; // Don't zip sub-directories
FileInputStream in = new FileInputStream(f); // Stream to read file
ZipEntry entry = new ZipEntry(f.getPath()); // Make a ZipEntry
out.putNextEntry(entry); // Store entry
while ((bytes_read = in.read(buffer)) != -1)
// Copy bytes
out.write(buffer, 0, bytes_read);
in.close(); // Close input stream
}
// When we're done with the whole loop, close the output stream
out.close();
}
/**
* This nested class is a test program that demonstrates the use of the static
* methods defined above.
*/
public static class Test {
/**
* Compress a specified file or directory. If no destination name is
* specified, append .gz to a file name or .zip to a directory name
*/
public static void main(String args[]) throws IOException {
if ((args.length != 1) && (args.length != 2)) { // check arguments
System.err.println("Usage: java Compress$Test <from> [<to>]");
System.exit(0);
}
String from = args[0], to;
File f = new File(from);
boolean directory = f.isDirectory(); // Is it a file or directory?
if (args.length == 2)
to = args[1];
else { // If destination not specified
if (directory)
to = from + ".zip"; // use a .zip suffix
else
to = from + ".gz"; // or a .gz suffix
}
if ((new File(to)).exists()) { // Make sure not to overwrite
System.err.println("Compress: won't overwrite existing file: " + to);
System.exit(0);
}
// Finally, call one of the methods defined above to do the work.
if (directory)
Compress.zipDirectory(from, to);
else
Compress.gzipFile(from, to);
}
}
}
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