bcd 8421码

bcd码表：

比如一个字符串 String s = "0200"
按对照表转换成二进制
02 : 0000 0010
00 : 0000 0000
s转换为字节的时候
02和00分别转换为一个字节
也就是说字符串"0200"bcd编码之后会是2个字节
代码：

public static byte[] str2bcdOne(String s) {
        //如果不是2的倍数,则补0
        if (s.length() % 2 != 0) {
            s = s + "0";
        }
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        //获得字符数组
        char[] cs = s.toCharArray();
        int high = 0;
        int low = 0;
        for (int i = 0; i < cs.length; i += 2) {
            if ((cs[i] >= '0') && (cs[i] <= '9'))
                //得到高位的十进制表示
                high = cs[i] - '0';
            else {
                //溢出
                high = cs[i] - '0' - 7;
            }

            if ((cs[(i + 1)] >= '0') && (cs[(i + 1)] <= '9'))
                //得到低位的十进制表示
                low = cs[(i + 1)] - '0';
            else {
                low = cs[(i + 1)] - '0' - 7;
            }
            System.out.println("high:" +high);
            System.out.println("high2:" +DataConverter.intToBinary(high));
            System.out.println("low:" + DataConverter.intToBinary(low));
            System.out.println("high << 4 | low:" + DataConverter.intToBinary(high << 4 | low));
            baos.write(high << 4 | low);
        }
        return baos.toByteArray();
    }