md5.java

java操作excel的类

/*
 * MD5 implementation
 * written Santeri Paavolainen, Helsinki Finland 1996
 * (c) Santeri Paavolainen, Helsinki Finland 1996
 * modifications Copyright (C) 2002-2004 Stephen Ostermiller 
 * http://ostermiller.org/contact.pl?regarding=Java+Utilities
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * See COPYING.TXT for details.
 * 
 * The original work by Santeri Paavolainen can be found at
 * http://www.helsinki.fi/~sjpaavol/programs/md5/
 * 
 * This Java class has been derived from the RSA Data Security, Inc. MD5 
 * Message-Digest Algorithm and its reference implementation. 
 */
package com.Ostermiller.util;

import java.io.*;

/**
 * MD5 hash generator.
 * More information about this class is available from <a target="_top" href=
 * "http://ostermiller.org/utils/MD5.html">ostermiller.org</a>.
 * <p>
 * This class takes as input a message of arbitrary length and produces
 * as output a 128-bit "fingerprint" or "message digest" of the input.
 * It is conjectured that it is computationally infeasible to produce
 * two messages having the same message digest, or to produce any
 * message having a given pre-specified target message digest. The MD5
 * algorithm is intended for digital signature applications, where a
 * large file must be "compressed" in a secure manner before being
 * encrypted with a private (secret) key under a public-key cryptosystem
 * such as RSA.
 * <p>
 * For more information see RFC1321.
 *
 * @see MD5OutputStream
 * @see MD5InputStream
 *
 * @author Santeri Paavolainen http://www.helsinki.fi/~sjpaavol/programs/md5/
 * @author Stephen Ostermiller http://ostermiller.org/contact.pl?regarding=Java+Utilities
 * @since ostermillerutils 1.00.00
 */
public class MD5 {

	/**
	 * Class constructor
	 *
	 * @since ostermillerutils 1.00.00
	 */
	public MD5 () {
		reset();
	} 

	/**
	 * Command line program that will take files as arguments
	 * and output the MD5 sum for each file.
	 *
	 * @param args command line arguments
	 *
	 * @since ostermillerutils 1.00.00
	 */
	public static void main (String[] args){
		if (args.length == 0){
			System.err.println("Please specify a file.");
		} else {
			for (int i=0; i<args.length; i++){
				try {
					System.out.println(MD5.getHashString(new File(args[i])) + " " + args[i]);
				} catch (IOException x){
					System.err.println(x.getMessage());
				}
			}
		}
	}

	/**
	 * Gets this hash sum as an array of 16 bytes.
	 *
	 * @return Array of 16 bytes, the hash of all updated bytes.
	 *
	 * @since ostermillerutils 1.00.00
	 */
	public byte[] getHash() {
		if (!finalState.valid) {
			finalState.copy(workingState);
			long bitCount = finalState.bitCount;
			// Compute the number of left over bits
			int leftOver = (int) (((bitCount >>> 3)) & 0x3f); 
			// Compute the amount of padding to add based on number of left over bits.
			int padlen = (leftOver < 56) ? (56 - leftOver) : (120 - leftOver);
			// add the padding
			update(finalState, padding, 0, padlen);
			// add the length (computed before padding was added)
			update(finalState, encode(bitCount), 0, 8);   
			finalState.valid = true;
		}
		// make a copy of the hash before returning it.
		return encode(finalState.state, 16);
	}

	/**
	 * Returns 32-character hex representation of this hash.
	 *
	 * @return String representation of this object's hash.
	 *
	 * @since ostermillerutils 1.00.00
	 */
	public String getHashString(){
		return toHex(this.getHash());
	}

	/**
	 * Gets the MD5 hash of the given byte array.
	 * 
	 * @param b byte array for which an MD5 hash is desired.
	 * @return Array of 16 bytes, the hash of all updated bytes.
	 *
	 * @since ostermillerutils 1.00.00
	 */
	public static byte[] getHash(byte[] b){
		MD5 md5 = new MD5();
		md5.update(b);
		return md5.getHash();
	}

	/**
	 * Gets the MD5 hash of the given byte array.
	 * 
	 * @param b byte array for which an MD5 hash is desired.
	 * @return 32-character hex representation the data's MD5 hash.
	 *
	 * @since ostermillerutils 1.00.00
	 */
	public static String getHashString(byte[] b){
		MD5 md5 = new MD5();
		md5.update(b);
		return md5.getHashString();
	}

	/**
	 * Gets the MD5 hash the data on the given InputStream.
	 * 
	 * @param in byte array for which an MD5 hash is desired.
	 * @return Array of 16 bytes, the hash of all updated bytes.
	 * @throws IOException if an I/O error occurs.
	 *
	 * @since ostermillerutils 1.00.00
	 */
	public static byte[] getHash(InputStream in) throws IOException {
		MD5 md5 = new MD5();
		byte[] buffer = new byte[1024];
		int read;
		while ((read = in.read(buffer)) != -1){
			md5.update(buffer, read);
		}
		return md5.getHash();
	}   

	/**
	 * Gets the MD5 hash the data on the given InputStream.
	 * 
	 * @param in byte array for which an MD5 hash is desired.
	 * @return 32-character hex representation the data's MD5 hash.
	 * @throws IOException if an I/O error occurs.
	 *
	 * @since ostermillerutils 1.00.00
	 */
	public static String getHashString(InputStream in) throws IOException {
		MD5 md5 = new MD5();
		byte[] buffer = new byte[1024];
		int read;
		while ((read = in.read(buffer)) != -1){
			md5.update(buffer, read);
		}
		return md5.getHashString();
	}

	/**
	 * Gets the MD5 hash of the given file.
	 * 
	 * @param f file for which an MD5 hash is desired.
	 * @return Array of 16 bytes, the hash of all updated bytes.
	 * @throws IOException if an I/O error occurs.
	 *
	 * @since ostermillerutils 1.00.00
	 */
	public static byte[] getHash(File f) throws IOException {
		return getHash(new FileInputStream(f));
	}

	/**
	 * Gets the MD5 hash of the given file.
	 * 
	 * @param f file array for which an MD5 hash is desired.
	 * @return 32-character hex representation the data's MD5 hash.
	 * @throws IOException if an I/O error occurs.
	 *
	 * @since ostermillerutils 1.00.00
	 */
	public static String getHashString(File f) throws IOException {
		return getHashString(new FileInputStream(f));
	}

	/**
	 * Gets the MD5 hash of the given String.
	 * The string is converted to bytes using the current
	 * platform's default character encoding.
	 * 
	 * @param s String for which an MD5 hash is desired.
	 * @return Array of 16 bytes, the hash of all updated bytes.
	 *
	 * @since ostermillerutils 1.00.00
	 */
	public static byte[] getHash(String s){
		MD5 md5 = new MD5();
		md5.update(s);
		return md5.getHash();
	}

	/**
	 * Gets the MD5 hash of the given String.
	 * The string is converted to bytes using the current
	 * platform's default character encoding.
	 * 
	 * @param s String for which an MD5 hash is desired.
	 * @return 32-character hex representation the data's MD5 hash.
	 *
	 * @since ostermillerutils 1.00.00
	 */
	public static String getHashString(String s){
		MD5 md5 = new MD5();
		md5.update(s);
		return md5.getHashString();
	}


	/**
	 * Gets the MD5 hash of the given String.
	 * 
	 * @param s String for which an MD5 hash is desired.
	 * @param enc The name of a supported character encoding.
	 * @return Array of 16 bytes, the hash of all updated bytes.
	 * @throws UnsupportedEncodingException If the named encoding is not supported.
	 *
	 * @since ostermillerutils 1.00.00
	 */
	public static byte[] getHash(String s, String enc) throws UnsupportedEncodingException {
		MD5 md5 = new MD5();
		md5.update(s, enc);
		return md5.getHash();
	}

	/**
	 * Gets the MD5 hash of the given String.
	 * 
	 * @param s String for which an MD5 hash is desired.
	 * @param enc The name of a supported character encoding.
	 * @return 32-character hex representation the data's MD5 hash.
	 * @throws UnsupportedEncodingException If the named encoding is not supported.
	 *
	 * @since ostermillerutils 1.00.00
	 */
	public static String getHashString(String s, String enc) throws UnsupportedEncodingException {
		MD5 md5 = new MD5();
		md5.update(s, enc);
		return md5.getHashString();
	}


	/**
	 * Reset the MD5 sum to its initial state.
	 *
	 * @since ostermillerutils 1.00.00
	 */
	public void reset() {
		workingState.reset();
		finalState.valid = false;
	}

	/**
	 * Returns 32-character hex representation of this hash.
	 *
	 * @return String representation of this object's hash.
	 *
	 * @since ostermillerutils 1.00.00
	 */
	public String toString(){
		return getHashString();
	}

	/** 
	 * Update this hash with the given data.
	 * <p>
	 * A state may be passed into this method so that we can add padding
	 * and finalize a md5 hash without limiting our ability to update
	 * more data later.
	 * <p>
	 * If length bytes are not available to be hashed, as many bytes as
	 * possible will be hashed.
	 *
	 * @param state Which state is updated.
	 * @param buffer Array of bytes to be hashed.
	 * @param offset Offset to buffer array.
	 * @param length number of bytes to hash.
	 *
	 * @since ostermillerutils 1.00.00
	 */
	private void update (MD5State state, byte buffer[], int offset, int length) {

		finalState.valid = false;

		// if length goes beyond the end of the buffer, cut it short.
		if ((length + offset) > buffer.length){
			length = buffer.length - offset;
		}

		// compute number of bytes mod 64 
		// this is what we have sitting in a buffer 
		// that have not been hashed yet
		int index = (int) (state.bitCount >>> 3) & 0x3f;

		// add the length to the count (translate bytes to bits)
		state.bitCount += length << 3;

		int partlen = 64 - index;        

		int i = 0;
		if (length >= partlen) {
			System.arraycopy(buffer, offset, state.buffer, index, partlen);
			transform(state, decode(state.buffer, 64, 0));
			for (i = partlen; (i + 63) < length; i+= 64){
				transform(state, decode(buffer, 64, i));
			}
			index = 0;
		}

		// buffer remaining input
		if (i < length) {
			for (int start = i; i < length; i++) {
				state.buffer[index + i - start] = buffer[i + offset];
			}
		}
	}

	/**
	 * Update this hash with the given data.
	 * <p>
	 * If length bytes are not available to be hashed, as many bytes as
	 * possible will be hashed.
	 *
	 * @param buffer Array of bytes to be hashed.
	 * @param offset Offset to buffer array.
	 * @param length number of bytes to hash.
	 *
	 * @since ostermillerutils 1.00.00
	 */
	public void update (byte buffer[], int offset, int length) {
		update(workingState, buffer, offset, length);
	}

	/**
	 * Update this hash with the given data.
	 * <p>
	 * If length bytes are not available to be hashed, as many bytes as
	 * possible will be hashed.
	 *
	 * @param buffer Array of bytes to be hashed.
	 * @param length number of bytes to hash.
	 *