Hex字符串与Bytes数组互相转换(应用场景：虹软byte数组

1. 基于Bytes数据与字符串之间的互相转换；
2. 灵活的设置截取的长度，方便剔除一些标志的字节；

/**  
 * @author wangyq  
 */
public class CustomHexUtils {  
  
    /**  
     * 根据传入的字节数组，返回字符串  
     * @param length 截取指定长度的数组  
     */  
    public static String getBytes2String(byte[] b, int length) {  
        StringBuilder stringBuffer = new StringBuilder(512);  
        for (int i = 0; i < length; ++i) {  
            String hex = Integer.toHexString(b[i] & 0xFF);  
            if (hex.length() == 1) {  
                hex = '0' + hex;  
            }  
            stringBuffer.append(hex.toUpperCase());  
        }  
        return stringBuffer.toString();  
    }  
    
    /**  
     * 将字符串转化为二进制byte数组  
     * @param hex 字符串  
     */  
    public static byte[] hexStringToByte(String hex) {  
        int len = (hex.length() / 2);  
        byte[] result = new byte[len];  
        char[] singleChar = hex.toCharArray();  
        for (int i = 0; i < len; i++) {  
            int pos = i * 2;  
            result[i] = (byte) (toByte(singleChar[pos]) << 4 | toByte(singleChar[pos + 1]));  
        }  
        return result;  
    }  
    
    /**  
     * 字符转byte  
     * @param c 字符  
     * @return byte  
     */    
  private static byte toByte(char c) {
        return (byte) "0123456789ABCDEF".indexOf(c);  
    }  
}