org.m1theo.apt.repo.utils.Utils.java Source code

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Here is the source code for org.m1theo.apt.repo.utils.Utils.java

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/**
 * Copyright (c) 2010-2013, theo@m1theo.org.
 * 
 * All rights reserved. This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v1.0 which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 */

package org.m1theo.apt.repo.utils;

import org.apache.commons.codec.binary.Hex;
import org.m1theo.apt.repo.exceptions.AptRepoException;

import java.io.*;
import java.security.DigestInputStream;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

/**
 * Providing utilities as static methods.
 * 
 * @author Theo Weiss
 * @since 0.1.0
 * 
 */
public class Utils {

    /**
     * Compute the given message digest for a file.
     * 
     * @param hashType algorithm to be used (as {@code String})
     * @param file File to compute the digest for (as {@code File}).
     * @return A {@code String} for the hex encoded digest.
     * @throws AptRepoException
     */
    public static String getDigest(String hashType, File file) throws AptRepoException {
        try {
            FileInputStream fis = new FileInputStream(file);
            BufferedInputStream bis = new BufferedInputStream(fis);
            MessageDigest digest = MessageDigest.getInstance(hashType);
            DigestInputStream dis = new DigestInputStream(bis, digest);
            @SuppressWarnings("unused")
            int ch;
            while ((ch = dis.read()) != -1)
                ;
            String hex = new String(Hex.encodeHex(digest.digest()));
            fis.close();
            bis.close();
            dis.close();
            return hex;
        } catch (NoSuchAlgorithmException e) {
            throw new AptRepoException("could not create digest", e);
        } catch (FileNotFoundException e) {
            throw new AptRepoException("could not create digest", e);
        } catch (IOException e) {
            throw new AptRepoException("could not create digest", e);
        }
    }

    /**
     * Compute md5, sha1, sha256 message digest for a file.
     * 
     * @param file File to compute the digest for (as {@code File}).
     * @return {@link DefaultHashes} with the computed digests.
     * @throws AptRepoException
     */
    public static DefaultHashes getDefaultDigests(File file) throws AptRepoException {
        DefaultHashes h = new DefaultHashes();
        for (Hashes hash : Hashes.values()) {
            String hex = getDigest(hash.toString(), file);
            switch (Hashes.values()[hash.ordinal()]) {
            case MD5:
                h.setMd5(hex);
                break;
            case SHA1:
                h.setSha1(hex);
                break;
            case SHA256:
                h.setSha256(hex);
                break;
            case SHA512:
                h.setSha512(hex);
                break;
            default:
                throw new AptRepoException("unknown hash type: " + hash.toString());
            }
        }
        return h;
    }

}