Java的String数字和BCD码相互转换

题目：例如将String="1234567890ABCDEF"转换为byte[]={0x12,0x34,0x56,0x78,0x90,0xAB,0xCD,0xEF}
代码如下：

public class javaHexStr
{
    public static byte[] str2Bcd(String asc) {
        int len = asc.length();
        int mod = len % 2;
        if (mod != 0) {
            asc = "0" + asc;
            len = asc.length();
        }
        byte abt[] = new byte[len];
        if (len >= 2) {
            len = len / 2;
        }
        byte bbt[] = new byte[len];
        abt = asc.getBytes();
        int j, k;
        for (int p = 0; p < asc.length() / 2; p++) {
            if ((abt[2 * p] >= '0') && (abt[2 * p] <= '9')) {
                j = abt[2 * p] - '0';
            } else if ((abt[2 * p] >= 'a') && (abt[2 * p] <= 'z')) {
                j = abt[2 * p] - 'a' + 0x0a;
            } else {
                j = abt[2 * p] - 'A' + 0x0a;
            }
            if ((abt[2 * p + 1] >= '0') && (abt[2 * p + 1] <= '9')) {
                k = abt[2 * p + 1] - '0';
            } else if ((abt[2 * p + 1] >= 'a') && (abt[2 * p + 1] <= 'z')) {
                k = abt[2 * p + 1] - 'a' + 0x0a;
            } else {
                k = abt[2 * p + 1] - 'A' + 0x0a;
            }
            int a = (j << 4) + k;
            byte b = (byte) a;
            bbt[p] = b;
            System.out.format("%02X\n", bbt[p]);
        }
        return bbt;
    }
     private static byte asc_to_bcd(byte asc) {
     byte bcd;

     if ((asc >= '0') && (asc <= '9'))
                bcd = (byte) (asc - '0');
     else if ((asc >= 'A') && (asc <= 'F'))
                bcd = (byte) (asc - 'A' + 10);
     else if ((asc >= 'a') && (asc <= 'f'))
                bcd = (byte) (asc - 'a' + 10);
     else
                bcd = (byte) (asc - 48);
     return bcd;
     }

     private static byte[] ASCII_To_BCD(byte[] ascii, int asc_len) {
     byte[] bcd = new byte[asc_len / 2];
     int j = 0;
     for (int i = 0; i < (asc_len + 1) / 2; i++) {
                bcd[i] = asc_to_bcd(ascii[j++]);
                bcd[i] = (byte) (((j >= asc_len) ? 0x00 : asc_to_bcd(ascii[j++])) + (bcd[i] << 4));
     System.out.format("%02X\n", bcd[i]);
     }
     return bcd;
     }

     public static String bcd2Str(byte[] bytes) {
     char temp[] = new char[bytes.length * 2], val;

     for (int i = 0; i < bytes.length; i++) {
                val = (char) (((bytes[i] & 0xf0) >> 4) & 0x0f);
                temp[i * 2] = (char) (val > 9 ? val + 'A' - 10 : val + '0');

                val = (char) (bytes[i] & 0x0f);
                temp[i * 2 + 1] = (char) (val > 9 ? val + 'A' - 10 : val + '0');
     }
     return new String(temp);
     }
    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        //System.out.print("Hello,World!");
         String s = "12345678123456781234567812345678";
     byte[] bcd = ASCII_To_BCD(s.getBytes(), s.length());
         //byte[] bcd = str2Bcd(s);
     // String s1 = bcd2Str(bcd);
     //System.out.print(s1);
    }


}