How to Unzip in Java

Here is a quick java program to unzip or explode a zip file. We will read the zip file with the help of java.util.ZipFile, then we will process each entries inside this. We will read the entries as stream and write to a buffer and eventually to a file output stream.  So at the end we will extract all the elements in the zip, and maintain the same hierarchical structure of directories .Please refer the below example.

	import java.io.File;
	import java.io.FileOutputStream;
	import java.io.IOException;
	import java.io.InputStream;
	import java.util.Enumeration;
	import java.util.zip.ZipEntry;
	import java.util.zip.ZipFile;
	public class UnZipDemo {
	public static void main(String args[]) throws IOException
	{
	String zipFileName = "D:\\demo.zip";
	ZipFile zipFile = new ZipFile(zipFileName);
	String extractedPath = "D:\\demo";
	byte[] buffer = new byte[1024];
	Enumeration enm = zipFile.entries();
	ZipEntry ze = null;
	InputStream fis = null;
	while (enm.hasMoreElements()) {
	ze = (ZipEntry) enm.nextElement();
	System.out.println("processing = "+ze.getName());
	File newFile = new File(extractedPath + File.separator + ze.getName());
	// create all non exists folders
	new File(newFile.getParent()).mkdirs();
	FileOutputStream fos = new FileOutputStream(newFile);
	int len;
	fis = zipFile.getInputStream(ze);
	while ((len = fis.read(buffer)) > 0) {
	fos.write(buffer, 0, len);
	}
	fos.close();
	fis.close();
	}
	}
	}

Zip files in Java

To create or read zip files in Java, we can use java.util.ZipFile. This allow to read an zip file and read the entries inside it. We can create a zip file by using ZipOutputStream.

Please refer the below example program

https://github.com/pallabrath/myexpjava/blob/master/myexpjava/src/demo/zipfile/ZipFileDemo.java

package demo.zipfile;

import java.io.FileOutputStream;

import java.io.IOException;

import java.io.InputStream;

import java.util.Enumeration;

import java.util.Scanner;

import java.util.zip.ZipEntry;

import java.util.zip.ZipFile;

import java.util.zip.ZipOutputStream;

public class ZipFileDemo {

public static void main(String args[]) throws IOException {

// create a zip file

String zipFileName = "D:\\demo.zip";

ZipOutputStream zipos = new ZipOutputStream(new FileOutputStream(zipFileName));

// In Zip Output Stream we can create file.

ZipEntry ze1 = new ZipEntry("file1.txt");

zipos.putNextEntry(ze1);

zipos.write("Hello World".getBytes());

zipos.closeEntry();

// Now lets create another file in a directory

zipos.putNextEntry(new ZipEntry("etc\\file2.txt"));

zipos.write("Hello Again".getBytes());

zipos.closeEntry();

zipos.close();

// To Read Zip file

ZipFile zipFile = new ZipFile(zipFileName);

// for specific entry

ZipEntry ze2 = zipFile.getEntry("file1.txt");

InputStream is = zipFile.getInputStream(ze2);

Scanner scan = new Scanner(is);

while (scan.hasNextLine()){

System.out.println(scan.nextLine());

}

scan.close();

Enumeration enm = zipFile.entries();

while(enm.hasMoreElements()) {

ZipEntry ze = (ZipEntry) enm.nextElement();

System.out.println(ze.getName());

}

}

}