@Async Spring annotation doesn't work

Question

I have a method that must create a zip and mat file from the original file uploaded from the user. So I decided to store only the original file and then, in an async task I would like to create the other two files. I read that the @Async annotation has two limit: 1)Only on public method 2)The @Async method must be in a differet object respect the caller class. So I create a new class and put in it my async method but it still doens't work. This is the class that calls the async method:

@Service
public class FleetAcquisitionServicesImpl implements FleetAcquisitionServices{

    @Autowired
    private DatabaseAcquisitionServices databaseAcquisitionServices;
    @Autowired
    private DatabaseFleetsAndCarsServices databaseFleetsAndCarsServices;

    @Autowired
    private FleetFolderName fleetFolderName; 

    private static final int NUMBER_OF_SHEET=4;
    @Override
    public ArrayList<String> uploadFiles(MultipartFile[] openedFiles, Integer idFleet, Integer idCar, Integer initialKm) throws FileUploadException, FileEmptyException{
        ArrayList<String> filesName=new ArrayList<String>();
        String fileName=null;
        String carPath=null;
        for (MultipartFile openedFile:openedFiles){
            if (!openedFile.isEmpty()) {
                //Copy the file into path specified
                fileName = openedFile.getOriginalFilename();
                try {
                    //Get the path where to store the file
                    Fleet fleet=databaseFleetsAndCarsServices.getFleetById(idFleet);
                    Car car=databaseFleetsAndCarsServices.getCarById(idCar);
                    carPath= fleetFolderName.createCarName(fleet, car);
                    if (FilenameUtils.getExtension(fileName).equals("dat")){
                        fileName = FilenameUtils.removeExtension(fileName)+"_km"+initialKm;
                        //write dat file
                        openedFile.transferTo(new File(carPath +"/"+ fileName+".dat"));                 
                        ZipAndMat.createZipAndMat(carPath,fileName);
                    }else
                        openedFile.transferTo(new File(carPath +"/"+ fileName));
                } catch (Exception e) {
                    throw new FileUploadException("you failed to upload " + fileName,e);
                }
                filesName.add(carPath +"/"+ fileName);
            } else {
                throw new FileEmptyException("your file is empty " + openedFile.getOriginalFilename());
            }
        }
        return filesName;
    }

ZipAndMat.createZipAndMat(carPath,fileName)

is the async method and it is here:

package com.model;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.concurrent.Future;
import java.util.zip.ZipEntry;
import java.util.zip.ZipOutputStream;

import org.springframework.scheduling.annotation.Async;
import org.springframework.scheduling.annotation.AsyncResult;

import com.mathworks.toolbox.javabuilder.MWException;

import dataconversion.Converter;

public class ZipAndMat {


    @Async
    public static Future<String> createZipAndMat(String filePath, String fileName){
        try {
            Thread.sleep(20000L);
        } catch (InterruptedException e1) {
            // TODO Auto-generated catch block
            e1.printStackTrace();
        }
        //Open file
        Path path = Paths.get(filePath, fileName + ".dat");
        try {
            //Create zip
            byte[] zip = zipBytes(Files.readAllBytes(path),fileName+".dat");
            Files.write(Paths.get(filePath +"/"+ fileName+".zip"), zip);
            //create mat file
            Converter objConv = new Converter();
            objConv. dat2MatConversion(filePath +"/", fileName + ".dat", 0.2);
        } catch (IOException e) {
            return new AsyncResult<String>("Zip not created");
        } catch (MWException e){
            return new AsyncResult<String>("Mat not created");
        }
        return new AsyncResult<String>("Zip created");
    }

    /**
     * Convert a file into zip file keeping the same name
     * @param filename
     * @param input
     * @return
     * @throws IOException
     */
    private static byte[] zipBytes( byte[] input, String filename) throws IOException {
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        ZipOutputStream zos = new ZipOutputStream(baos);
        ZipEntry entry = new ZipEntry(filename);
        entry.setSize(input.length);
        zos.putNextEntry(entry);
        zos.write(input);
        zos.closeEntry();
        zos.close();
        return baos.toByteArray();
    }

}

I tried tu but @EnableAsync both the caller class and on the confiuration class but it doesn't works. What is wrong in my code? the static method? Thanks

Answer 1

You need the following things:

1. @EnableAsync on a configuration class to enable async processing in Spring.
2. @Service or @Component on your ZipAndMat class to discover it as a Spring component.
3. Change your createZipAndMat method so it's not static.

4. Autowire this new Spring component in your FleetAcquisitionServicesImpl like this:

   @Autowired private ZipAndMat zipAndMat;

Then, instead of invoking the static method ZipAndMat.createZipAndMat(carPath,fileName); you'll need to invoke it on the autowired spring component instance like this:

zipAndMat.createZipAndMat(carPath,fileName);

Answer 2

You need to do below thing to enable async

1.) @Service public class ZipAndMat ...

2.) Caller class should enable async call using @EnableAsync

@EnableAsync @Service public class FleetAcquisitionServicesImpl implements FleetAcquisitionServices

Please follow this link for more details https://spring.io/guides/gs/async-method/