MD5Util

MD5Util

/*
 * Classname       : MD5Util
 * Create Date     : Aug 15, 2006
 */

import java.security.MessageDigest;

/**
 * 
 * JAVA MD5加密
 * 
 * @author   Larry
 * 
 * @version  1.0
 */
public class MD5Util {

    public MD5Util() {
    }

    private final static String[] hexDigits = { "0", "1", "2", "3", "4", "5",
            "6", "7", "8", "9", "a", "b", "c", "d", "e", "f" };

    /**
     * 转换字节数组为16进制字串
     * @param b 字节数组
     * @return 16进制字串
     */
    public static String byteArrayToString(byte[] b) {
        StringBuffer resultSb = new StringBuffer();
        for (int i = 0; i < b.length; i++) {
            resultSb.append(byteToHexString(b[i]));//若使用本函数转换则可得到加密结果的16进制表示，即数字字母混合的形式
            //resultSb.append(byteToNumString(b[i]));//使用本函数则返回加密结果的10进制数字字串，即全数字形式
        }
        return resultSb.toString();
    }

    private static String byteToNumString(byte b) {

        int _b = b;
        if (_b < 0) {
            _b = 256 + _b;
        }
        return String.valueOf(_b);
    }

    private static String byteToHexString(byte b) {
        int n = b;
        if (n < 0) {
            n = 256 + n;
        }
        int d1 = n / 16;
        int d2 = n % 16;
        return hexDigits[d1] + hexDigits[d2];
    }

    public static String MD5Encode(String origin) {
        String resultString = null;
        try {
            resultString = new String(origin);
            MessageDigest md = MessageDigest.getInstance("MD5");
            resultString = byteArrayToString(md.digest(resultString.getBytes()));
        } catch (Exception ex) {
        }
        return resultString;
    }

    /**
     * 进行md5字符中的比较
     * @param md5a String
     * @param md5b String
     * @return boolean
     */
    public static boolean compareMD5(String md5a, String md5b) {
        boolean flag = false;
        if (md5a == md5b) {
            return true;
        }
        try {
            java.security.MessageDigest alga = java.security.MessageDigest.getInstance("MD5");
            flag = alga.isEqual(md5a.getBytes(), md5b.getBytes());
        } catch (Exception ex) {
        }
        return flag;
    }

        public static void main(String args[]) {
            String m = MD5Util.MD5Encode("aisa100");
            System.out.println(m);
    
            String m1 = MD5Util.MD5Encode("fb271113cf95966bfc917a735d065ffa");
            System.out.println(m1);
            System.out.println(MD5Util.compareMD5(m1, m));
        }
}