edu.jhuapl.ses.vtkjavanativelibs.Util Maven / Gradle / Ivy

Go to download
/*
 * Copyright 2016 University of Basel, Graphics and Vision Research Group
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package edu.jhuapl.ses.vtkjavanativelibs;

import java.io.*;
import java.net.URL;
import java.security.DigestInputStream;
import java.security.MessageDigest;
import java.util.Arrays;

import static edu.jhuapl.ses.vtkjavanativelibs.VtkNativeLibraries.MAJOR_VERSION;
import static edu.jhuapl.ses.vtkjavanativelibs.VtkNativeLibraries.MINOR_VERSION;

public class Util {
	private Util() {
	}


	public static File createNativeDirectory(File nativeLibraryBaseDirectory) throws VtkJavaNativeLibraryException {

		File nativeLibraryDirectory  = new File(nativeLibraryBaseDirectory, "vtkjavanatives-" +MAJOR_VERSION + "." +MINOR_VERSION);
		try {
			if (!nativeLibraryDirectory.exists()) {
				nativeLibraryDirectory.mkdirs();
			}
		} catch (Throwable t) {
			throw new VtkJavaNativeLibraryException(
					"Unable to create directory for native libs", t);
		}
		return nativeLibraryDirectory;
	}

	public static byte[] getDigest(URL url) throws VtkJavaNativeLibraryException, IOException {
		byte[] digest = null;

		try {
			BufferedInputStream is = new BufferedInputStream(url.openStream());

			MessageDigest md = MessageDigest.getInstance("MD5");
			DigestInputStream dis = new DigestInputStream(is, md);

			byte[] buffer = new byte[4096 * 512];
			for (int read = is.read(buffer); read >= 0; read = is.read(buffer)) {
				md.update(buffer, 0, read);
			}
			digest = md.digest();
			is.close();
		}

		catch (java.security.NoSuchAlgorithmException e) {
			throw new VtkJavaNativeLibraryException("Error while computing MD5 hash for url " + url, e);
		}

		return digest;
	}

	public static void copyUrlToFile(URL url, File file) throws IOException, VtkJavaNativeLibraryException {

		BufferedInputStream is = new BufferedInputStream(url.openStream());
		if (file.exists() && Arrays.equals(getDigest(url), getDigest(file.toURI().toURL()))) {
			// nothing to do, we just return
			return;
		}

		// otherwise we copy the file from the jar to the path.
		BufferedOutputStream os = new BufferedOutputStream(
				new FileOutputStream(file));

		byte[] buffer = new byte[4096 * 512];
		for (int read = is.read(buffer); read >= 0; read = is.read(buffer)) {
			os.write(buffer, 0, read);
		}
		is.close();
		os.close();
	}

}