import org.joget.apps.form.service.FileUtil;
import org.joget.commons.util.SetupManager;
import java.lang.String;
import org.springframework.context.ApplicationContext;
import org.apache.commons.io.FileUtils;
import org.apache.commons.io.FilenameUtils;
import java.io.File;
//This method creates a copy of the file uploaded via File Upload form element in Joget and appends the name of the person who uploaded the file. This works whether you've used the default base path under System Settings or if you've changed the default base path for the file upload. 
//Here, I'm using the destination directory structure as <FILE_UPLOAD_BASE_PATH>/filesWithRequesters/app_formuploads/<TABLE_NAME>/<CURRENT_PROCESSID>/.. against the default Joget file storage path as : <FILE_UPLOAD_BASE_PATH>/app_formuploads/<TABLE_NAME>/<CURRENT_PROCESSID>/..
//Please replace 'fileUpload' everywhere with the name of the table the form is bound to.
//Please replace 'requester' in Line 33 with the fieldID of the form field which contains the name of the user whose username has to be appended with the file.
//Please replace 'file' in '#form.fileUpload.file#' with the fieldID of the file upload form field.
//Please change the below destinationDirectory variable according to your need. 
public void updateFileName(){
	try{
		String sourceDirectory="";
		ApplicationContext ac = FileUtil.getApplicationContext();
		String formUploadPath = SetupManager.getBaseDirectory();
		SetupManager setupManager = (SetupManager) ac.getBean("setupManager");
		String dataFileBasePath = setupManager.getSettingValue("dataFileBasePath");
		if(dataFileBasePath!=null && dataFileBasePath.length() > 0){
			sourceDirectory=dataFileBasePath;
		}
		else{
			sourceDirectory=formUploadPath;
		}
		String destinationDirectory = sourceDirectory+File.separator+"filesWithRequesters"+File.separator+"app_formuploads"+File.separator+"fileUpload"+File.separator+"#assignment.processId#"+File.separator;
		sourceDirectory+=File.separator+"app_formuploads"+File.separator+"fileUpload"+File.separator+"#assignment.processId#"+File.separator;
		String sourceFilePath = sourceDirectory+"#form.fileUpload.file#";
		String fileExtension = FilenameUtils.getExtension(sourceFilePath);
		String destinationFilePath = FilenameUtils.removeExtension(destinationDirectory+"#form.fileUpload.file#");
		destinationFilePath += "_"+"#form.fileUpload.requester#."+fileExtension;
		File sourceFile = new File(sourceDirectory+"#form.fileUpload.file#");
		File destinationFile = new File(destinationFilePath);
		FileUtils.copyFile(sourceFile,destinationFile);
	}
	catch(Exception e){
		System.out.println("Some error occurred in renaming the file. "+e);
	}
}
return updateFileName();