Java GZIP Example – Compress and Decompress File

Filed Under: Java

Welcome to Java GZIP example. GZIP is one of the favorite tool to compress file in Unix systems. We can compress a single file in GZIP format but we can’t compress and archive a directory using GZIP like ZIP files.

Java GZIP

GZIP, Java GZIP Example
Here is a simple java GZIP example program showing how can we compress a file to GZIP format and then decompress the GZIP file to create a new file.

GZIPExample.java


package com.journaldev.files;

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.zip.GZIPInputStream;
import java.util.zip.GZIPOutputStream;

public class GZIPExample {

    public static void main(String[] args) {
        String file = "/Users/pankaj/sitemap.xml";
        String gzipFile = "/Users/pankaj/sitemap.xml.gz";
        String newFile = "/Users/pankaj/new_sitemap.xml";
        
        compressGzipFile(file, gzipFile);
        
        decompressGzipFile(gzipFile, newFile);
               
    }

    private static void decompressGzipFile(String gzipFile, String newFile) {
        try {
            FileInputStream fis = new FileInputStream(gzipFile);
            GZIPInputStream gis = new GZIPInputStream(fis);
            FileOutputStream fos = new FileOutputStream(newFile);
            byte[] buffer = new byte[1024];
            int len;
            while((len = gis.read(buffer)) != -1){
                fos.write(buffer, 0, len);
            }
            //close resources
            fos.close();
            gis.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
        
    }

    private static void compressGzipFile(String file, String gzipFile) {
        try {
            FileInputStream fis = new FileInputStream(file);
            FileOutputStream fos = new FileOutputStream(gzipFile);
            GZIPOutputStream gzipOS = new GZIPOutputStream(fos);
            byte[] buffer = new byte[1024];
            int len;
            while((len=fis.read(buffer)) != -1){
                gzipOS.write(buffer, 0, len);
            }
            //close resources
            gzipOS.close();
            fos.close();
            fis.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
        
    }

}

While decompressing a GZIP file, if it’s not in GZIP format, following exception will be thrown.


java.util.zip.ZipException: Not in GZIP format
	at java.util.zip.GZIPInputStream.readHeader(GZIPInputStream.java:164)
	at java.util.zip.GZIPInputStream.<init>(GZIPInputStream.java:78)
	at java.util.zip.GZIPInputStream.<init>(GZIPInputStream.java:90)
	at com.journaldev.files.GZIPExample.decompressGzipFile(GZIPExample.java:25)
	at com.journaldev.files.GZIPExample.main(GZIPExample.java:18)

That’s all for Java GZIP Example.

Comments

  1. Mayur Musrif says:

    Excellent example.
    Thanks for sharing.

  2. Tomek says:

    Hi
    When compressing the file, before you gzipOS.close() run gzipOS.finish().
    It should help.

  3. Rituraj Dharwadkar says:

    Hey can u please mail me the explanation of this program… step wise..

  4. longlife says:

    This post is very helpful.
    Could you please make a sample gzip xml file available for download.
    Plus, is there an easy way to generate a gzip json file?

    Thanks,

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