package com.tiangua.star.util;

import java.security.MessageDigest;

/**
 * The type Md 5 util.
 */
public abstract class MD5Util {
    /**
     * Md 5 string.
     *
     * @param pwd the pwd
     * @return the string
     */
    public final static String MD5(String pwd) {
        //用于加密的字符  
        char md5String[] = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',  
                'A', 'B', 'C', 'D', 'E', 'F' };  
        try {  
            //使用平台的默认字符集将此 String 编码为 byte序列，并将结果存储到一个新的 byte数组中  
            byte[] btInput = pwd.getBytes();  
               
            //信息摘要是安全的单向哈希函数，它接收任意大小的数据，并输出固定长度的哈希值。  
            MessageDigest mdInst = MessageDigest.getInstance("MD5");  
               
            //MessageDigest对象通过使用 update方法处理数据， 使用指定的byte数组更新摘要  
            mdInst.update(btInput);  
               
            // 摘要更新之后，通过调用digest（）执行哈希计算，获得密文  
            byte[] md = mdInst.digest();  
               
            // 把密文转换成十六进制的字符串形式  
            int j = md.length;  
            char str[] = new char[j * 2];  
            int k = 0;  
            for (int i = 0; i < j; i++) {   //  i = 0  
                byte byte0 = md[i];  //95  
                str[k++] = md5String[byte0 >>> 4 & 0xf];    //    5   
                str[k++] = md5String[byte0 & 0xf];   //   F  
            }  
               
            //返回经过加密后的字符串  
            return new String(str);  
               
        } catch (Exception e) {  
            return null;  
        }  
    }

    private static String byteArrayToHexString(byte b[]) {
        StringBuffer resultSb = new StringBuffer();
        for (int i = 0; i < b.length; i++)
            resultSb.append(byteToHexString(b[i]));

        return resultSb.toString();
    }

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

    /**
     * Md 5 encode string.
     *
     * @param origin      the origin
     * @param charsetname the charsetname
     * @return the string
     */
    public static String MD5Encode(String origin, String charsetname) {
        String resultString = null;
        try {
            resultString = new String(origin);
            MessageDigest md = MessageDigest.getInstance("MD5");
            if (charsetname == null || "".equals(charsetname))
                resultString = byteArrayToHexString(md.digest(resultString
                        .getBytes()));
            else
                resultString = byteArrayToHexString(md.digest(resultString
                        .getBytes(charsetname)));
        } catch (Exception exception) {
        }
        return resultString;
    }

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

    public static void main(String[] a) {
        System.out.println(MD5Encode("13758525535NsArzbOcYie4XMW5iGrkA","UTF-8"));
    }
}