Java MD5 加密类

    /*************************************************  
    md5 类实现了RSA Data Security,Inc.在提交给IETF  
    的RFC1321中的MD5 message-digest 算法。  
    *************************************************/    
    public class MD5 {    
      /* 下面这些S11-S44实际上是一个4*4的矩阵，在原始的C实现中是用#define 实现的，  
      这里把它们实现成为static final是表示了只读，切能在同一个进程空间内的多个  
      Instance间共享*/    
        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 };    
        /* 下面的三个成员是MD5计算过程中用到的3个核心数据，在原始的C实现中  
          被定义到MD5_CTX结构中  
         
          */    
        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    
           
      /* digestHexStr是MD5的唯一一个公共成员，是最新一次计算结果的  
      　 16进制ASCII表示.  
      */    
        public String digestHexStr;    
           
        /* digest,是最新一次计算结果的2进制内部表示，表示128bit的MD5值.  
      */    
        private byte[] digest = new byte[16];    
           
      /*  
        getMD5ofStr是类MD5最主要的公共方法，入口参数是你想要进行MD5变换的字符串  
        返回的是变换完的结果，这个结果是从公共成员digestHexStr取得的．  
      */    
        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;    
        
        }    
        // 这是MD5这个类的标准构造函数，JavaBean要求有一个public的并且没有参数的构造函数    
        public MD5() {    
              md5Init();    
        
              return;    
        }    
        /* md5Init是一个初始化函数，初始化核心变量，装入标准的幻数 */    
        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;    
        }    
        /* F,G,H,I 是4个基本的MD5函数，在原始的MD5的C实现中，由于它们是    
        简单的位运算，可能出于效率的考虑把它们实现成了宏，在java中，我们把它们    
      　　实现成了private方法，名字保持了原来C中的。 */    
        
        private long F(long x,long y,long z) {    
              return (x & y) | ((~x) & z);    
        
        }    
        private long G(long x,long z) {    
              return (x & z) | (y & (~z));    
        
        }    
        private long H(long x,long z) {    
              return x ^ y ^ z;    
        }    
        
        private long I(long x,long z) {    
              return y ^ (x | (~z));    
        }    
           
        /*  
          FF,GG,HH和II将调用F,I进行近一步变换  
          FF,HH,and II transformations for rounds 1,2,3,and 4.  
          Rotation is separate from addition to prevent recomputation.  
        */    
        
        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 ac) {    
              a += G (b,d) + x + ac;    
              a = ((int) a << s) | ((int) a >>> (32 - s));    
              a += b;    
              return a;    
        }    
        private long HH(long a,long ac) {    
              a += H (b,d) + x + ac;    
              a = ((int) a << s) | ((int) a >>> (32 - s));    
              a += b;    
              return a;    
        }    
        private long II(long a,long ac) {    
              a += I (b,d) + x + ac;    
              a = ((int) a << s) | ((int) a >>> (32 - s));    
              a += b;    
              return a;    
        }    
        /*  
          md5Update是MD5的主计算过程，inbuf是要变换的字节串，inputlen是长度，这个  
          函数由getMD5ofStr调用，调用之前需要调用md5init，因此把它设计成private的  
        */    
        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,partLen);    
                    md5Transform(buffer);    
        
                    for (i = partLen; i + 63 < inputLen; i += 64) {    
        
                        md5Memcpy(block,i,64);    
                        md5Transform (block);    
                    }    
                    index = 0;    
        
              } else    
        
                    i = 0;    
        
              ///* Buffer remaining input */    
              md5Memcpy(buffer,inputLen - i);    
        
        }    
           
        /*  
          md5Final整理和填写输出结果  
        */    
        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);    
        
        }    
             
        /* md5Memcpy是一个内部使用的byte数组的块拷贝函数，从input的inpos开始把len长度的  
    　　　　　 字节拷贝到output的outpos位置开始  
        */    
        
        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];    
        }    
           
        /*  
          md5Transform是MD5核心变换程序，有md5Update调用，block是分块的原始字节  
        */    
        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,d,x[0],S11,0xd76aa478L); /* 1 */    
              d = FF (d,a,x[1],S12,0xe8c7b756L); /* 2 */    
              c = FF (c,x[2],S13,0x242070dbL); /* 3 */    
              b = FF (b,x[3],S14,0xc1bdceeeL); /* 4 */    
              a = FF (a,x[4],0xf57c0fafL); /* 5 */    
              d = FF (d,x[5],0x4787c62aL); /* 6 */    
              c = FF (c,x[6],0xa8304613L); /* 7 */    
              b = FF (b,x[7],0xfd469501L); /* 8 */    
              a = FF (a,x[8],0x698098d8L); /* 9 */    
              d = FF (d,x[9],0x8b44f7afL); /* 10 */    
              c = FF (c,x[10],0xffff5bb1L); /* 11 */    
              b = FF (b,x[11],0x895cd7beL); /* 12 */    
              a = FF (a,x[12],0x6b901122L); /* 13 */    
              d = FF (d,x[13],0xfd987193L); /* 14 */    
              c = FF (c,x[14],0xa679438eL); /* 15 */    
              b = FF (b,x[15],0x49b40821L); /* 16 */    
        
              /* Round 2 */    
              a = GG (a,S21,0xf61e2562L); /* 17 */    
              d = GG (d,S22,0xc040b340L); /* 18 */    
              c = GG (c,S23,0x265e5a51L); /* 19 */    
              b = GG (b,S24,0xe9b6c7aaL); /* 20 */    
              a = GG (a,0xd62f105dL); /* 21 */    
              d = GG (d,0x2441453L); /* 22 */    
              c = GG (c,0xd8a1e681L); /* 23 */    
              b = GG (b,0xe7d3fbc8L); /* 24 */    
              a = GG (a,0x21e1cde6L); /* 25 */    
              d = GG (d,0xc33707d6L); /* 26 */    
              c = GG (c,0xf4d50d87L); /* 27 */    
              b = GG (b,0x455a14edL); /* 28 */    
              a = GG (a,0xa9e3e905L); /* 29 */    
              d = GG (d,0xfcefa3f8L); /* 30 */    
              c = GG (c,0x676f02d9L); /* 31 */    
              b = GG (b,0x8d2a4c8aL); /* 32 */    
        
              /* Round 3 */    
              a = HH (a,S31,0xfffa3942L); /* 33 */    
              d = HH (d,S32,0x8771f681L); /* 34 */    
              c = HH (c,S33,0x6d9d6122L); /* 35 */    
              b = HH (b,S34,0xfde5380cL); /* 36 */    
              a = HH (a,0xa4beea44L); /* 37 */    
              d = HH (d,0x4bdecfa9L); /* 38 */    
              c = HH (c,0xf6bb4b60L); /* 39 */    
              b = HH (b,0xbebfbc70L); /* 40 */    
              a = HH (a,0x289b7ec6L); /* 41 */    
              d = HH (d,0xeaa127faL); /* 42 */    
              c = HH (c,0xd4ef3085L); /* 43 */    
              b = HH (b,0x4881d05L); /* 44 */    
              a = HH (a,0xd9d4d039L); /* 45 */    
              d = HH (d,0xe6db99e5L); /* 46 */    
              c = HH (c,0x1fa27cf8L); /* 47 */    
              b = HH (b,0xc4ac5665L); /* 48 */    
        
              /* Round 4 */    
              a = II (a,S41,0xf4292244L); /* 49 */    
              d = II (d,S42,0x432aff97L); /* 50 */    
              c = II (c,S43,0xab9423a7L); /* 51 */    
              b = II (b,S44,0xfc93a039L); /* 52 */    
              a = II (a,0x655b59c3L); /* 53 */    
              d = II (d,0x8f0ccc92L); /* 54 */    
              c = II (c,0xffeff47dL); /* 55 */    
              b = II (b,0x85845dd1L); /* 56 */    
              a = II (a,0x6fa87e4fL); /* 57 */    
              d = II (d,0xfe2ce6e0L); /* 58 */    
              c = II (c,0xa3014314L); /* 59 */    
              b = II (b,0x4e0811a1L); /* 60 */    
              a = II (a,0xf7537e82L); /* 61 */    
              d = II (d,0xbd3af235L); /* 62 */    
              c = II (c,0x2ad7d2bbL); /* 63 */    
              b = II (b,0xeb86d391L); /* 64 */    
        
              state[0] += a;    
              state[1] += b;    
              state[2] += c;    
              state[3] += d;    
        
        }    
           
        /*Encode把long数组按顺序拆成byte数组，因为java的long类型是64bit的，  
          只拆低32bit，以适应原始C实现的用途  
        */    
        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);    
              }    
        }    
        
        /*Decode把byte数组按顺序合成成long数组，因为java的long类型是64bit的，  
          只合成低32bit，高32bit清零，以适应原始C实现的用途  
        */    
        private void Decode (long[] output,j;    
        
        
              for (i = 0,j += 4)    
                    output[i] = b2iu(input[j]) |    
                        (b2iu(input[j + 1]) << 8) |    
                        (b2iu(input[j + 2]) << 16) |    
                        (b2iu(input[j + 3]) << 24);    
        
              return;    
        }    
           
        /*  
          b2iu是我写的一个把byte按照不考虑正负号的原则的＂升位＂程序，因为java没有unsigned运算  
        */    
        public static long b2iu(byte b) {    
              return b < 0 ? b & 0x7F + 128 : b;    
        }    
           
      /*byteHEX()，用来把一个byte类型的数转换成十六进制的ASCII表示，  
      　因为java中的byte的toString无法实现这一点，我们又没有C语言中的  
        sprintf(outbuf,"%02X",ib)  
      */    
        public 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;    
        }    
        public static void main(String args[]){    
            MD5 md5 = new MD5();    
            System.out.println(md5.getMD5ofStr("admin"));    
        }    
    }