MD5加密

import java.security.MessageDigest;

/**
 * md5加密 <功能详细描述>
 * 
 * @author wanglei
 * @version [版本号, Feb 28, 2011]
 * @see [相关类/方法]
 * @since WihomeV100R001C02LGDM05
*/
public class Md5Util
{
    private static final String[] HEXDIGITS = {"0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "a", "b", "c", "d",
            "e", "f"};

    private static final int NUM256 = 256;

    private static final int NUM16 = 16;

    /**
     * 对字符串进行MD5加密 <功能详细描述>
     * 
     * @param originString String
     * @return String
     * @see [类、类#方法、类#成员]
*/
    public static String generatePassword(String originString)
    {
        if (originString != null)
        {
            try
            {
                MessageDigest md = MessageDigest.getInstance("MD5");
                // 使用指定的字节数组对摘要进行最后更新，然后完成摘要计算
                byte[] results = md.digest(originString.getBytes());
                // 将得到的字节数组变成字符串返回
                String resultString = byteArrayToHexString(results);
                return resultString;
            }
            catch (Exception ex)
            {
                ex.printStackTrace();
            }
        }
        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();
    }

    /**
     * 将一个字节转化成十六进制形式的字符串 <功能详细描述>
     * 
     * @param b byte
     * @return String
     * @see [类、类#方法、类#成员]
*/
    private static String byteToHexString(byte b)
    {
        int n = b;
        if (n < 0)
        {
            n = NUM256 + n;
        }
        int d1 = n / NUM16;
        int d2 = n % NUM16;
        return HEXDIGITS[d1] + HEXDIGITS[d2];
    }
}