FileDownloaderJob.java

package eu.europeana.cloud.downloader;

import eu.europeana.cloud.common.model.Representation;
import eu.europeana.cloud.mcs.driver.FileServiceClient;
import eu.europeana.cloud.mcs.driver.exception.DriverException;
import eu.europeana.cloud.service.mcs.exception.MCSException;
import eu.europeana.cloud.util.FileUtil;
import eu.europeana.cloud.util.MimeTypeHelper;
import org.apache.tika.mime.MediaType;
import org.apache.tika.mime.MimeTypeException;

import java.io.IOException;
import java.io.InputStream;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;

/**
 * Created by Tarek on 9/14/2016.
 */
public class FileDownloaderJob implements Callable<Void> {
    private FileServiceClient fileServiceClient;
    private String folderPath;
    private Representation representation;
    private String fileName;
    private static final int MAX_RETRY_COUNT = 3;
    private static final int TIME_BETWEEN_RETRIES = 1000; //One second

    public FileDownloaderJob(FileServiceClient fileServiceClient, String fileName, Representation representation, String folderPath) {
        this.fileServiceClient = fileServiceClient;
        this.fileName = fileName;
        this.representation = representation;
        this.folderPath = folderPath;
    }

    @Override
    public final Void call() throws InterruptedException, ExecutionException, DriverException, MCSException, IOException, MimeTypeException {
        persistFileToFolderWithRetry(0, MAX_RETRY_COUNT);
        return null;
    }

    private void persistFileToFolder() throws MimeTypeException, DriverException, IOException, MCSException {
        final String fileUrl = fileServiceClient.getFileUri(representation.getCloudId(), representation.getRepresentationName(), representation.getVersion(), fileName).toString();
        InputStream inputStream = fileServiceClient.getFile(fileUrl);
        String extension = getExtension(inputStream);
        String persistedName = representation.getVersion() + "_" + fileName;
        FileUtil.persistStreamToFile(inputStream, folderPath, persistedName, extension);
    }

    private void persistFileToFolderWithRetry(int retryCount, int retryLimit) throws InterruptedException, MimeTypeException, IOException, MCSException {
        try {
            persistFileToFolder();
        } catch (DriverException | MCSException e) {
            if (retryCount > retryLimit) {
                throw e;
            }
            Thread.sleep(TIME_BETWEEN_RETRIES);
            persistFileToFolderWithRetry(++retryCount, retryLimit);
        }

    }

    private String getExtension(InputStream inputStream) throws MimeTypeException, IOException {
        MediaType mimeType = MimeTypeHelper.getMediaTypeFromStream(inputStream);
        return MimeTypeHelper.getExtension(mimeType);

    }

}