Java MD5 String md5(File f)

Description

md

License

Educational Community License

Declaration

public static final String md5(File f) throws IOException 

Method Source Code

//package com.java2s;
/**//from  w  w  w .j ava2s .c  om
 *  Copyright 2009, 2010 The Regents of the University of California
 *  Licensed under the Educational Community 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.osedu.org/licenses/ECL-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.
 *
 */

import java.io.File;
import java.io.FileInputStream;

import java.io.IOException;
import java.io.InputStream;
import java.security.DigestInputStream;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

public class Main {
    public static final String md5(File f) throws IOException {
        byte[] bytes = new byte[1024];
        InputStream is = null;
        try {
            MessageDigest md = MessageDigest.getInstance("MD5");
            is = new DigestInputStream(new FileInputStream(f), md);
            while ((is.read(bytes)) >= 0) {
            }
            return hex(md.digest());
        } catch (NoSuchAlgorithmException e) {
            throw new IOException("No MD5 algorithm available");
        } finally {
            is.close();
        }
    }

    /**
     * Converts the checksum to a hex string.
     * 
     * @param data
     *          the digest
     * @return the digest hex representation
     */
    private static String hex(byte[] data) {
        StringBuffer buf = new StringBuffer();
        for (int i = 0; i < data.length; i++) {
            int halfbyte = (data[i] >>> 4) & 0x0F;
            int two_halfs = 0;
            do {
                if ((0 <= halfbyte) && (halfbyte <= 9))
                    buf.append((char) ('0' + halfbyte));
                else
                    buf.append((char) ('a' + (halfbyte - 10)));
                halfbyte = data[i] & 0x0F;
            } while (two_halfs++ < 1);
        }
        return buf.toString();
    }
}

Related

1. md5()
2. md5(File f)
3. md5(File f)
4. md5(File f)
5. md5(File file)