带有留言功能的java实例

package com.cn.util; 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, 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 }; /* 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 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)); } /* FF,GG,HH和II将调用F,G,H,I进行近一步变换 FF, GG, 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 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; } /* 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, 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); } /* 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, 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,