//实现MD5算法的类，提供一个静态的函数toMD5()供调用；
//还提供一个getMD5ofStr()函数生成一个MD5加密串；
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 char Hex[]={'0','1','2','3','4','5','6','7','8','9','A','B','C','D','E','F'};
    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[];
    private long count[];
    private byte buffer[];
    public String digestHexStr;
    private byte digest[];
    private byte test;
    public String getMD5ofStr(String s)
    {//返回MD5串；
        int i;
        md5Init();
        md5Update(s.getBytes(), s.length());
        md5Final();
        digestHexStr = "";
        for(i = 0;i<16;i++)
          digestHexStr=digestHexStr+byteHEX(digest[i]);
        return digestHexStr;
    }
    public MD5()
    {
        state = new long[4];
        count = new long[2];
        buffer = new byte[64];
        digest = new byte[16];
        md5Init();
    }
    private void md5Init()
    {//初始化部分变量；
        count[0] = 0L;
        count[1] = 0L;
        state[0] = 0x67452301L;