Java Unzip File Example

Welcome to Java Unzip File Example. In the last post, we learned how to zip file and directory in java, here we will unzip the same zip file created from directory to another output directory.

Java Unzip File

To unzip a zip file, we need to read the zip file with ZipInputStream and then read all the ZipEntry one by one. Then use FileOutputStream to write them to file system. We also need to create the output directory if it doesn’t exists and any nested directories present in the zip file. Here is the java unzip file program that unzips the earlier created tmp.zip to output directory.

package com.journaldev.files;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.zip.ZipEntry;
import java.util.zip.ZipInputStream;

public class UnzipFiles {

    public static void main(String[] args) {
        String zipFilePath = "/Users/pankaj/tmp.zip";
        
        String destDir = "/Users/pankaj/output";
        
        unzip(zipFilePath, destDir);
    }

    private static void unzip(String zipFilePath, String destDir) {
        File dir = new File(destDir);
        // create output directory if it doesn't exist
        if(!dir.exists()) dir.mkdirs();
        FileInputStream fis;
        //buffer for read and write data to file
        byte[] buffer = new byte[1024];
        try {
            fis = new FileInputStream(zipFilePath);
            ZipInputStream zis = new ZipInputStream(fis);
            ZipEntry ze = zis.getNextEntry();
            while(ze != null){
                String fileName = ze.getName();
                File newFile = new File(destDir + File.separator + fileName);
                System.out.println("Unzipping to "+newFile.getAbsolutePath());
                //create directories for sub directories in zip
                new File(newFile.getParent()).mkdirs();
                FileOutputStream fos = new FileOutputStream(newFile);
                int len;
                while ((len = zis.read(buffer)) > 0) {
                fos.write(buffer, 0, len);
                }
                fos.close();
                //close this ZipEntry
                zis.closeEntry();
                ze = zis.getNextEntry();
            }
            //close last ZipEntry
            zis.closeEntry();
            zis.close();
            fis.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
        
    }

}

Once the program finishes, we have all the zip file contents in the output folder with same directory hierarchy. Output of the above program is:

Unzipping to /Users/pankaj/output/.DS_Store
Unzipping to /Users/pankaj/output/data/data.dat
Unzipping to /Users/pankaj/output/data/data.xml
Unzipping to /Users/pankaj/output/data/xmls/project.xml
Unzipping to /Users/pankaj/output/data/xmls/web.xml
Unzipping to /Users/pankaj/output/data.Xml
Unzipping to /Users/pankaj/output/DB.xml
Unzipping to /Users/pankaj/output/item.XML
Unzipping to /Users/pankaj/output/item.xsd
Unzipping to /Users/pankaj/output/ms/data.txt
Unzipping to /Users/pankaj/output/ms/project.doc

That’s all about java unzip file example.