Java: How to create zip archive from byte array data.

Beside create compressed archive from files, We can create from byte array that is stored in memory and not necessary to write byte array down to disk before create it. For this reason, the application will have better performance because less I/O operation.

The following tutorial, we show how to create zip archive from byte array.

1. Add dependency.

<!-- https://mvnrepository.com/artifact/org.apache.commons/commons-compress -->

<dependency>

           <groupId>org.apache.commons</groupId>

           <artifactId>commons-compress</artifactId>

           <version>1.15</version>

</dependency>

2. Implement The following example code.

2.1 Write to file.

package com.haruka.compressfilebytearraydemo;

import java.io.FileOutputStream;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

import org.apache.commons.compress.archivers.zip.ZipArchiveEntry;
import org.apache.commons.compress.archivers.zip.ZipArchiveOutputStream;



public class App

{

    public static void main( String[] args )

    {

     ZipArchiveOutputStream zOutputStream = null;

     FileOutputStream fileOutputStream = null;

     try {

      List<byte[]> byteArrayListToWrite = new ArrayList<byte[]>();

      byteArrayListToWrite.add("THIS IS DATA TO TEST WHRITE ZIP WITH BYTE ARRAY 1".getBytes());

      byteArrayListToWrite.add("THIS IS DATA TO TEST WHRITE ZIP WITH BYTE ARRAY 2".getBytes());

      byteArrayListToWrite.add("THIS IS DATA TO TEST WHRITE ZIP WITH BYTE ARRAY 3".getBytes());



      fileOutputStream = new FileOutputStream("C:\\DEMO\\bytearrayarchivedemo.zip"); //path to save archive file.

      zOutputStream = new ZipArchiveOutputStream(fileOutputStream);

      

      for(int i=0;i<byteArrayListToWrite.size();i++) {

       byte[] dataToWrite = byteArrayListToWrite.get(i);

       ZipArchiveEntry zEntry = new ZipArchiveEntry("file_"+i+".txt"); // create zip entry and specific file name.

       zEntry.setSize(dataToWrite.length); //set size of data.
       zOutputStream.putArchiveEntry(zEntry); //add entry.

       zOutputStream.write(dataToWrite);

       zOutputStream.closeArchiveEntry(); // commit added entry (commit file).

      }

     }catch(Exception ex) {

      ex.printStackTrace();

     }finally {

       try {

        if(zOutputStream != null) {

         zOutputStream.flush(); //save file.

         zOutputStream.close();

        }

        if(fileOutputStream != null) {

         fileOutputStream.close();

        }

    } catch (IOException e) {

     e.printStackTrace();

    }

     }

    }

}

 2.2 Write to servlet response.

package com.haruka.compressfilebytearraydemoservlet.servlet;



import java.io.FileOutputStream;

import java.io.IOException;

import java.util.ArrayList;

import java.util.List;



import javax.servlet.ServletException;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;



import org.apache.commons.compress.archivers.zip.ZipArchiveEntry;

import org.apache.commons.compress.archivers.zip.ZipArchiveOutputStream;



public class CompressFileByteArrayDemo extends HttpServlet{

 @Override

 protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

  ZipArchiveOutputStream zOutputStream = null;

     try {

      List<byte[]> byteArrayListToWrite = new ArrayList<byte[]>();

      byteArrayListToWrite.add("THIS IS DATA TO TEST WHRITE ZIP WITH BYTE ARRAY 1".getBytes());

      byteArrayListToWrite.add("THIS IS DATA TO TEST WHRITE ZIP WITH BYTE ARRAY 2".getBytes());

      byteArrayListToWrite.add("THIS IS DATA TO TEST WHRITE ZIP WITH BYTE ARRAY 3".getBytes());

      response.setContentType("application/zip"); //set content type

      zOutputStream = new ZipArchiveOutputStream(response.getOutputStream());

      

      for(int i=0;i<byteArrayListToWrite.size();i++) {

       byte[] dataToWrite = byteArrayListToWrite.get(i);

       ZipArchiveEntry zEntry = new ZipArchiveEntry("file_"+i+".txt"); // create zip entry and specific file name.

       zEntry.setSize(dataToWrite.length); //set size of data.

       zOutputStream.putArchiveEntry(zEntry); //add entry.

       zOutputStream.write(dataToWrite);

       zOutputStream.closeArchiveEntry(); // commit added entry (commit file).

      }

     }catch(Exception ex) {

      ex.printStackTrace();

     }finally {

       try {

        if(zOutputStream != null) {

         zOutputStream.flush(); //save file.

         zOutputStream.close();

        }

    } catch (IOException e) {

     e.printStackTrace();

    }

     }

 }

}

Furthermore, the example can be adapt with other outputStream for any purpose.

The example can be downloaded in following github:

1. For write to file example.
https://github.com/benzyaa/javademo/tree/master/compressfilebytearraydemo

2. For write to servlet response.
https://github.com/benzyaa/javademo/tree/master/compressfilebytearraydemoservlet

Further Information: 

https://commons.apache.org/proper/commons-compress/index.html

https://mvnrepository.com/artifact/org.apache.commons/commons-compress