Apex Demo for zip file download

ZipDownloadDemoController.cls

public with sharing class ZipDownloadDemoController {

  // Constructor
  public ZipDownloadDemoController() {
  }
  
  @RemoteAction
  public static PageReference getZipDownloadUrl(String objectId) {
  
    Zippex newZip = new Zippex();
    List<Attachment> attachments = [SELECT Name, Body FROM Attachment WHERE ParentId = :objectId];
    
    for(Attachment att : attachments ) {
      newZip.addFile('folder/' + att.Name, att.Body, null);
    }    
    Blob zipData = newZip.getZipArchive();
        
    Document d = new Document();
    d.name = 'demo.zip';
    d.body = zipData;
    d.folderId = UserInfo.getUserId();
    insert d;
  
    PageReference pageRef = new PageReference('/servlet/servlet.FileDownload?file=' + d.Id);
    pageRef.setRedirect(true);

    return pageRef;
  }

}