public void download()

in taverna-download-impl/src/main/java/org/apache/taverna/download/impl/DownloadManagerImpl.java [76:126]
42 lines of code
8 McCabe index (conditional complexity)

	public void download(URI source, Path destination, String digestAlgorithm, URI digestSource)
			throws DownloadException {

		MessageDigest md = null;
		if (digestAlgorithm != null) {
			try {
				md = MessageDigest.getInstance(digestAlgorithm);
			} catch (NoSuchAlgorithmException e) {
				throw new IllegalArgumentException("Unsupported digestAlgorithm: " + digestAlgorithm, e);
			}
		}

		// download the file
		Path tempFile;
		try {
			tempFile = Files.createTempFile(destination.getParent(), "." + destination.getFileName(), ".tmp");
		} catch (IOException e1) {
			// perhaps a permission problem?
			throw new DownloadException("Can't create temporary file in folder " + destination.getParent(), e1);
		}
		logger.info(String.format("Downloading %1$s to %2$s", source, tempFile));
		downloadToFile(source, tempFile);

		if (digestSource != null) {
			// download the digest file
			String expectedDigest;
			expectedDigest = downloadHash(digestSource).trim().toLowerCase(Locale.ROOT);
			// check if the digest matches
			try {
				try (InputStream s = Files.newInputStream(tempFile)) {
					DigestUtils.updateDigest(md, s);
					String actualDigest = Hex.encodeHexString(md.digest());
					if (!actualDigest.equals(expectedDigest)) {
						throw new DownloadException(
								String.format("Error downloading file: checksum mismatch (%1$s != %2$s)",
										actualDigest, expectedDigest));
					}
				}
			} catch (IOException e) {
				throw new DownloadException(String.format("Error checking digest for %1$s", destination), e);
			}
		}
		// All fine, move to destination
		try {
			logger.info(String.format("Copying %1$s to %2$s", tempFile, destination));
			Files.move(tempFile, destination, StandardCopyOption.ATOMIC_MOVE, StandardCopyOption.REPLACE_EXISTING);
		} catch (IOException e) {
			throw new DownloadException(String.format("Error downloading %1$s to %2$s.", source, destination), e);
		}

	}