java之MD5

public class MD5 { 
   

	static final int S11 = 7;

	static final int S12 = 12;

	static final int S13 = 17;

	static final int S14 = 22;

	static final int S21 = 5;

	static final int S22 = 9;

	static final int S23 = 14;

	static final int S24 = 20;

	static final int S31 = 4;

	static final int S32 = 11;

	static final int S33 = 16;

	static final int S34 = 23;

	static final int S41 = 6;

	static final int S42 = 10;

	static final int S43 = 15;

	static final int S44 = 21;

	static final byte[] PADDING = { 
    -128, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
			0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
			0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
			0, 0, 0, 0, 0, 0, 0 };

	private long[] state = new long[4]; // state (ABCD)

	private long[] count = new long[2]; // number of bits, modulo 2^64 (lsb

	// first)
	private byte[] buffer = new byte[64]; // input buffer

	/** * �������һ�εļ����� */
	public String digestHexStr;

	private byte[] digest = new byte[16];

	/** * ��inbuf����MD5ת�� * * @param inbuf * @return */
	public String getMD5ofStr(String inbuf) { 
   
		md5Init();
		md5Update(inbuf.getBytes(), inbuf.length());
		md5Final();
		digestHexStr = "";
		for (int i = 0; i < 16; i++) { 
   
			digestHexStr += byteHEX(digest[i]);
		}
		return digestHexStr;
	}

	public MD5() { 
   
		md5Init();
		return;
	}

	/** * ��ʼ�� */
	private void md5Init() { 
   
		count[0] = 0L;
		count[1] = 0L;
		// /* Load magic initialization constants.

		state[0] = 0x67452301L;
		state[1] = 0xefcdab89L;
		state[2] = 0x98badcfeL;
		state[3] = 0x10325476L;

		return;
	}

	private long F(long x, long y, long z) { 
   
		return (x & y) | ((~x) & z);

	}

	private long G(long x, long y, long z) { 
   
		return (x & z) | (y & (~z));

	}

	private long H(long x, long y, long z) { 
   
		return x ^ y ^ z;
	}

	private long I(long x, long y, long z) { 
   
		return y ^ (x | (~z));
	}

	private long FF(long a, long b, long c, long d, long x, long s, long ac) { 
   
		a += F(b, c, d) + x + ac;
		a = ((int) a << s) | ((int) a >>> (32 - s));
		a += b;
		return a;
	}

	private long GG(long a, long b, long c, long d, long x, long s, long ac) { 
   
		a += G(b, c, d) + x + ac;
		a = ((int) a << s) | ((int) a >>> (32 - s));
		a += b;
		return a;
	}

	private long HH(long a, long b, long c, long d, long x, long s, long ac) { 
   
		a += H(b, c, d) + x + ac;
		a = ((int) a << s) | ((int) a >>> (32 - s));
		a += b;
		return a;
	}

	private long II(long a, long b, long c, long d, long x, long s, long ac) { 
   
		a += I(b, c, d) + x + ac;
		a = ((int) a << s) | ((int) a >>> (32 - s));
		a += b;
		return a;
	}

	/**
	 * �������
	 * 
	 * @param inbuf
	 * @param inputLen
	 */
	private void md5Update(byte[] inbuf, int inputLen) { 
   

		int i, index, partLen;
		byte[] block = new byte[64];
		index = (int) (count[0] >>> 3) & 0x3F;
		// /* Update number of bits */
		if ((count[0] += (inputLen << 3)) < (inputLen << 3))
			count[1]++;
		count[1] += (inputLen >>> 29);

		partLen = 64 - index;

		// Transform as many times as possible.
		if (inputLen >= partLen) { 
   
			md5Memcpy(buffer, inbuf, index, 0, partLen);
			md5Transform(buffer);

			for (i = partLen; i + 63 < inputLen; i += 64) { 
   

				md5Memcpy(block, inbuf, 0, i, 64);
				md5Transform(block);
			}
			index = 0;

		} else
			i = 0;
		// /* Buffer remaining input */
		md5Memcpy(buffer, inbuf, index, i, inputLen - i);
	}

	/** * ������ */
	private void md5Final() { 
   
		byte[] bits = new byte[8];
		int index, padLen;

		// /* Save number of bits */
		Encode(bits, count, 8);

		// /* Pad out to 56 mod 64.
		index = (int) (count[0] >>> 3) & 0x3f;
		padLen = (index < 56) ? (56 - index) : (120 - index);
		md5Update(PADDING, padLen);

		// /* Append length (before padding) */
		md5Update(bits, 8);

		// /* Store state in digest */
		Encode(digest, state, 16);
	}

	/** * �ڲ�ʹ�õ�byte����Ŀ鿽������ * * @param output * @param input * @param outpos * @param inpos * @param len */
	private void md5Memcpy(byte[] output, byte[] input, int outpos, int inpos,
			int len) { 
   
		int i;
		for (i = 0; i < len; i++)
			output[outpos + i] = input[inpos + i];
	}

	/** * md5����任 * * @param block */
	private void md5Transform(byte block[]) { 
   
		long a = state[0], b = state[1], c = state[2], d = state[3];
		long[] x = new long[16];
		Decode(x, block, 64);
		/* Round 1 */
		a = FF(a, b, c, d, x[0], S11, 0xd76aa478L); /* 1 */
		d = FF(d, a, b, c, x[1], S12, 0xe8c7b756L); /* 2 */
		c = FF(c, d, a, b, x[2], S13, 0x242070dbL); /* 3 */
		b = FF(b, c, d, a, x[3], S14, 0xc1bdceeeL); /* 4 */
		a = FF(a, b, c, d, x[4], S11, 0xf57c0fafL); /* 5 */
		d = FF(d, a, b, c, x[5], S12, 0x4787c62aL); /* 6 */
		c = FF(c, d, a, b, x[6], S13, 0xa8304613L); /* 7 */
		b = FF(b, c, d, a, x[7], S14, 0xfd469501L); /* 8 */
		a = FF(a, b, c, d, x[8], S11, 0x698098d8L); /* 9 */
		d = FF(d, a, b, c, x[9], S12, 0x8b44f7afL); /* 10 */
		c = FF(c, d, a, b, x[10], S13, 0xffff5bb1L); /* 11 */
		b = FF(b, c, d, a, x[11], S14, 0x895cd7beL); /* 12 */
		a = FF(a, b, c, d, x[12], S11, 0x6b901122L); /* 13 */
		d = FF(d, a, b, c, x[13], S12, 0xfd987193L); /* 14 */
		c = FF(c, d, a, b, x[14], S13, 0xa679438eL); /* 15 */
		b = FF(b, c, d, a, x[15], S14, 0x49b40821L); /* 16 */
		/* Round 2 */
		a = GG(a, b, c, d, x[1], S21, 0xf61e2562L); /* 17 */
		d = GG(d, a, b, c, x[6], S22, 0xc040b340L); /* 18 */
		c = GG(c, d, a, b, x[11], S23, 0x265e5a51L); /* 19 */
		b = GG(b, c, d, a, x[0], S24, 0xe9b6c7aaL); /* 20 */
		a = GG(a, b, c, d, x[5], S21, 0xd62f105dL); /* 21 */
		d = GG(d, a, b, c, x[10], S22, 0x2441453L); /* 22 */
		c = GG(c, d, a, b, x[15], S23, 0xd8a1e681L); /* 23 */
		b = GG(b, c, d, a, x[4], S24, 0xe7d3fbc8L); /* 24 */
		a = GG(a, b, c, d, x[9], S21, 0x21e1cde6L); /* 25 */
		d = GG(d, a, b, c, x[14], S22, 0xc33707d6L); /* 26 */
		c = GG(c, d, a, b, x[3], S23, 0xf4d50d87L); /* 27 */
		b = GG(b, c, d, a, x[8], S24, 0x455a14edL); /* 28 */
		a = GG(a, b, c, d, x[13], S21, 0xa9e3e905L); /* 29 */
		d = GG(d, a, b, c, x[2], S22, 0xfcefa3f8L); /* 30 */
		c = GG(c, d, a, b, x[7], S23, 0x676f02d9L); /* 31 */
		b = GG(b, c, d, a, x[12], S24, 0x8d2a4c8aL); /* 32 */
		/* Round 3 */
		a = HH(a, b, c, d, x[5], S31, 0xfffa3942L); /* 33 */
		d = HH(d, a, b, c, x[8], S32, 0x8771f681L); /* 34 */
		c = HH(c, d, a, b, x[11], S33, 0x6d9d6122L); /* 35 */
		b = HH(b, c, d, a, x[14], S34, 0xfde5380cL); /* 36 */
		a = HH(a, b, c, d, x[1], S31, 0xa4beea44L); /* 37 */
		d = HH(d, a, b, c, x[4], S32, 0x4bdecfa9L); /* 38 */
		c = HH(c, d, a, b, x[7], S33, 0xf6bb4b60L); /* 39 */
		b = HH(b, c, d, a, x[10], S34, 0xbebfbc70L); /* 40 */
		a = HH(a, b, c, d, x[13], S31, 0x289b7ec6L); /* 41 */
		d = HH(d, a, b, c, x[0], S32, 0xeaa127faL); /* 42 */
		c = HH(c, d, a, b, x[3], S33, 0xd4ef3085L); /* 43 */
		b = HH(b, c, d, a, x[6], S34, 0x4881d05L); /* 44 */
		a = HH(a, b, c, d, x[9], S31, 0xd9d4d039L); /* 45 */
		d = HH(d, a, b, c, x[12], S32, 0xe6db99e5L); /* 46 */
		c = HH(c, d, a, b, x[15], S33, 0x1fa27cf8L); /* 47 */
		b = HH(b, c, d, a, x[2], S34, 0xc4ac5665L); /* 48 */
		/* Round 4 */
		a = II(a, b, c, d, x[0], S41, 0xf4292244L); /* 49 */
		d = II(d, a, b, c, x[7], S42, 0x432aff97L); /* 50 */
		c = II(c, d, a, b, x[14], S43, 0xab9423a7L); /* 51 */
		b = II(b, c, d, a, x[5], S44, 0xfc93a039L); /* 52 */
		a = II(a, b, c, d, x[12], S41, 0x655b59c3L); /* 53 */
		d = II(d, a, b, c, x[3], S42, 0x8f0ccc92L); /* 54 */
		c = II(c, d, a, b, x[10], S43, 0xffeff47dL); /* 55 */
		b = II(b, c, d, a, x[1], S44, 0x85845dd1L); /* 56 */
		a = II(a, b, c, d, x[8], S41, 0x6fa87e4fL); /* 57 */
		d = II(d, a, b, c, x[15], S42, 0xfe2ce6e0L); /* 58 */
		c = II(c, d, a, b, x[6], S43, 0xa3014314L); /* 59 */
		b = II(b, c, d, a, x[13], S44, 0x4e0811a1L); /* 60 */
		a = II(a, b, c, d, x[4], S41, 0xf7537e82L); /* 61 */
		d = II(d, a, b, c, x[11], S42, 0xbd3af235L); /* 62 */
		c = II(c, d, a, b, x[2], S43, 0x2ad7d2bbL); /* 63 */
		b = II(b, c, d, a, x[9], S44, 0xeb86d391L); /* 64 */
		state[0] += a;
		state[1] += b;
		state[2] += c;
		state[3] += d;
	}

	/** * ��long[]ת��Ϊbyte[] * * @param output * @param input * @param len */
	private void Encode(byte[] output, long[] input, int len) { 
   
		int i, j;

		for (i = 0, j = 0; j < len; i++, j += 4) { 
   
			output[j] = (byte) (input[i] & 0xffL);
			output[j + 1] = (byte) ((input[i] >>> 8) & 0xffL);
			output[j + 2] = (byte) ((input[i] >>> 16) & 0xffL);
			output[j + 3] = (byte) ((input[i] >>> 24) & 0xffL);
		}
	}

	/** * ��byte[]ת��Ϊlong[] * * @param output * @param input * @param len */
	private void Decode(long[] output, byte[] input, int len) { 
   
		int i, j;

		for (i = 0, j = 0; j < len; i++, j += 4)
			output[i] = b2iu(input[j]) | (b2iu(input[j + 1]) << 8)
					| (b2iu(input[j + 2]) << 16) | (b2iu(input[j + 3]) << 24);

		return;
	}

	/** * ��byte��λ * * @param b * @return */
	private static long b2iu(byte b) { 
   
		return b < 0 ? b & 0x7F + 128 : b;
	}

	/** * ��byteת��Ϊ16�����ַ� * * @param ib * @return */
	private static String byteHEX(byte ib) { 
   
		char[] Digit = { 
    '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A',
				'B', 'C', 'D', 'E', 'F' };
		char[] ob = new char[2];
		ob[0] = Digit[(ib >>> 4) & 0X0F];
		ob[1] = Digit[ib & 0X0F];
		String s = new String(ob);
		return s;
	}

	/** * ��str��MD5���� * * @param str * @return */
	public static String getDigest(String str) { 
   
		MD5 md5 = new MD5();
		return md5.getMD5ofStr(str);
	}

	public static void main(String args[]) { 
   
/* System.out.println("MD5(\"\"):" + MD5.getDigest(new Date().toString())); Set set=new HashSet(); for(int i=0;i<500000;i++){ String uuid=MD5.getDigest(new Date().getTime()+""); System.out.println(uuid); set.add(uuid) ; } System.out.println(set.size());*/
	
	System.out.println(getDigest("123"));
	}
}