Java I/O How to - GZIP compress with GZIPOutputStream

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Question

We would like to know how to gZIP compress with GZIPOutputStream.

Answer

        // w  w w  .  java  2s . c  o  m

import java.io.BufferedOutputStream;
import java.io.BufferedReader;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.FileReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.zip.GZIPInputStream;
import java.util.zip.GZIPOutputStream;

public class GZIPcompress {
  public static void main(String[] args) throws IOException {
    if (args.length == 0) {
      System.out.println("Usage: \nGZIPcompress file\n" + "\tUses GZIP compression to compress "
          + "the file to test.gz");
      System.exit(1);
    }
    BufferedReader in = new BufferedReader(new FileReader(args[0]));
    BufferedOutputStream out = new BufferedOutputStream(new GZIPOutputStream(new FileOutputStream(
        "test.gz")));
    System.out.println("Writing file");
    int c;
    while ((c = in.read()) != -1)
      out.write(c);
    in.close();
    out.close();
    System.out.println("Reading file");
    BufferedReader in2 = new BufferedReader(new InputStreamReader(new GZIPInputStream(
        new FileInputStream("test.gz"))));
    String s;
    while ((s = in2.readLine()) != null)
      System.out.println(s);
  }
}

The code above generates the following result.

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