How to Zip Files in Java

This post shows how you can zip files in Java. Using the options given here you can zip a single file or more than one file by specifying all those files.

Zip a file in Java

To zip files in Java there are two options-

Using ZipOutputStream and ZipEntry classes residing in java.util.zip package.
Using the Zip File System Provider- The zip file system provider treats a zip or JAR file as a file system and provides the ability to manipulate the contents of the file. The zip file system provider was introduced in the JDK 7 release.

Want to zip a folder, check this post How to Zip a Folder in Java

Table of contents

Zipping single fie in Java using ZipOutputStream
Zipping single fie in Java using Zip File System Provider
Zipping multiple files in Java

Zipping single fie in Java using ZipOutputStream

The steps for zipping a file using ZipOutputStream are as follows-

Create an InputStream for reading the source file.
Create an OutputStream for the zip file and wrap it in a ZipOutputStream object.
Create a ZipEntry instance for the source file and add it to the ZipOutputStream.
Read data from the source file and write it to the ZIP file.
Close the streams.

public class ZipFile {
  public static void main(String[] args) {
    // source file
    String fileName = "F:\\knpcode\\links.txt";
    File file = new File(fileName);
    //Creating zipfile name from fileName by 
    // truncating .txt and appending .zip
    String zipFilename = fileName.substring(0, fileName.indexOf('.')) + ".zip";
    File zipFile = new File(zipFilename);
    zipFile(file, zipFile);
  }
	
  // Method to zip file
  private static void zipFile(File file, File zippedFile){
    final int BUFFER = 1024;
    ZipOutputStream zos = null;
    BufferedInputStream bis = null;
    try{
      FileInputStream fis = new FileInputStream(file);
      bis = new BufferedInputStream(fis, BUFFER);          
      // Creating ZipOutputStream for writing to zip file
      FileOutputStream fos = new FileOutputStream(zippedFile);
      zos = new ZipOutputStream(fos);
      // Each file in the zipped archive is represented by a ZipEntry 
      // Only source file name is needed 
      ZipEntry ze = new ZipEntry(file.getName());        
      zos.putNextEntry(ze);
      byte data[] = new byte[BUFFER];
      int count;
      while((count = bis.read(data, 0, BUFFER)) != -1) {
        zos.write(data, 0, count);
      }                     
    } catch (IOException e) {
      // TODO Auto-generated catch block
      e.printStackTrace();
    }finally{
      try {
        zos.close();
        bis.close();
      } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
      }  
    }
  }
}

Zipping single fie in Java using Zip File System Provider

You can use the factory methods of the java.nio.file.FileSystems class to create a new zip file system or to obtain a reference to an existing zip file system.

You can create a zip file system by specifying the path of the zip or JAR file in following way-

URI uri = URI.create("jar:file:/PATH/TO/ZIPFILE");
FileSystem fs = FileSystems.newFileSystem(uri, env);

public class ZipFile {
  public static void main(String[] args) {
    // source file
    String fileName = "F:/knpcode/links.txt";
    //Creating zipfile name from fileName by 
    // truncating .txt and appending .zip
    String zipFilename = fileName.substring(0, fileName.indexOf('.')) + ".zip";
    
    zipFile(fileName, zipFilename);
  }

  private static void zipFile(String file, String zippedFile){
    Map<String, String> env = new HashMap<>(); 
    env.put("create", "true");
    // locate file system by using the syntax 
    // defined in java.net.JarURLConnection
    URI uri = URI.create("jar:file:/" + zippedFile);
    try (FileSystem zipfs = FileSystems.newFileSystem(uri.normalize(), env)) {
      Path sourceFile = Paths.get(file);
      System.out.println("Name-- " + sourceFile.getFileName().toString());
      Path pathInZipfile = zipfs.getPath(sourceFile.getFileName().toString());          
      // copy a file into the zip file
      Files.copy(sourceFile, pathInZipfile, StandardCopyOption.REPLACE_EXISTING ); 
    } catch (IOException e) {
      // TODO Auto-generated catch block
      e.printStackTrace();
    } 
  }
}

Zipping multiple files in Java

Here is an example of zipping multiple files in Java using ZipOutputStream where each source file is added as a ZipEntry to the ZipOutputStream.

public class ZipFile {
  public static void main(String[] args) {
    try {
      // source files
      String file1 = "F:/knpcode/links.txt";
      String file2 = "F:/knpcode/Test/postend.txt";
      // Zipped file name
      String zipFilename = "F:/knpcode/result.zip";
      File zipFile = new File(zipFilename);
      // Creating ZipOutputStream for writing to zip file
      FileOutputStream fos  = new FileOutputStream(zipFile);			
      ZipOutputStream zos = new ZipOutputStream(fos);
      
      zipFile(file1, zos);
      zipFile(file2, zos);
      zos.close();
    } catch (IOException e) {
      // TODO Auto-generated catch block
      e.printStackTrace();
    }
  }
	
  // Method to zip file
  private static void zipFile(String fileName, ZipOutputStream zos) throws IOException{
  final int BUFFER = 1024;
  BufferedInputStream bis = null;
  try{
    File file = new File(fileName);
    FileInputStream fis = new FileInputStream(file);
    bis = new BufferedInputStream(fis, BUFFER);          

    // Each file in the zipped archive is represented by a ZipEntry 
    // Only source file name is needed 
    ZipEntry zipEntry = new ZipEntry(file.getName());        
    zos.putNextEntry(zipEntry);
    byte data[] = new byte[BUFFER];
    int count;
    while((count = bis.read(data, 0, BUFFER)) != -1) {
      zos.write(data, 0, count);
    }    
      zos.closeEntry();
    } finally{
      try {
        bis.close();
      } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
      }  
    }
  }
}

That's all for the topic How to Zip Files in Java. If something is missing or you have something to share about the topic please write a comment.

You may also like

KnpCode

February 3, 2024