How to compress files in ZIP format using Java

Here is an example how to compress files in ZIP format using Java.

Example

The purpose of this tutorial is to take a file or a folder and compress into an archive all the files and sub-folders keeping the structure. For these classes from the java.util.zip package will be used.

There are two options for compression:

• STORED: uncompressed entries.
• DEFLATED: compressed entries.

package com.admfactory.io.archive;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import java.util.zip.ZipEntry;
import java.util.zip.ZipOutputStream;

public class CreateZIPArchive {

    public static void main(String[] args) {

	String output = "D:\\admfactory.com\\archive.zip";
	String source = "D:\\admfactory.com\\dir1\\";

	System.out.println("Zip Archive Example");
	System.out.println();
	System.out.println("Output to Zip : " + output);
	System.out.println();
	List<String> fileList = getAllFileList(new File(source));

	zip(output, fileList);
    }

    /**
     * Zip the list received as parameter
     * 
     * @param zipFile
     *            output ZIP file location
     */
    public static void zip(String zipFile, List<String> fileList) {

	byte[] buffer = new byte[1024];

	try {
	    FileOutputStream fos = new FileOutputStream(zipFile);
	    ZipOutputStream zos = new ZipOutputStream(fos);
	    zos.setMethod(ZipOutputStream.DEFLATED);
	    
	    for (String file : fileList) {

		System.out.println("File added: " + file);
		ZipEntry ze = new ZipEntry(file);
		zos.putNextEntry(ze);

		FileInputStream in = new FileInputStream(file);

		int len;
		while ((len = in.read(buffer)) > 0) {
		    zos.write(buffer, 0, len);
		}

		in.close();
	    }

	    zos.closeEntry();

	    zos.close();

	    System.out.println();
	    System.out.println("Done!");
	} catch (IOException ex) {
	    ex.printStackTrace();
	}
    }

    /**
     * Traverse a directory and get all files, and add the file into fileList
     * 
     * @param file
     *            file or directory
     * @return the list with all files to be added
     */
    public static ArrayList<String> getAllFileList(File file) {

	ArrayList<String> result = new ArrayList<String>();
	/** add the file only */
	if (file.isFile()) {
	    result.add(file.getAbsolutePath());
	    /** add all files from the folder */
	} else if (file.isDirectory()) {
	    File[] files = file.listFiles();
	    for (File f : files) {
		result.addAll(getAllFileList(f));
	    }
	}
	return result;
    }

}

Output

Zip Archive Example

Output to Zip : D:\admfactory.com\archive.zip

File added: D:\admfactory.com\dir1\dir3\dir4\f6.txt
File added: D:\admfactory.com\dir1\dir3\dir4\f7.txt
File added: D:\admfactory.com\dir1\dir3\f4.txt
File added: D:\admfactory.com\dir1\dir3\f5.txt
File added: D:\admfactory.com\dir1\f1.txt
File added: D:\admfactory.com\dir1\f2.txt
File added: D:\admfactory.com\dir1\f3.txt

Done!

Also, you can check the archive file created.

References

• ZipEntry