package tools;
import java.math.BigInteger;

public class Jiaoyan {
	
	/**获取校验码除去包头相加取反*/
	public static byte[] check(byte[] byt) {
		
		//字节数组转为16进制字符串/2后的长度
		int size=BinaryToHexString2(byt).length()/2;
		String[] hex=hex(BinaryToHexString2(byt));
		
		//求和
		int sum=0;
		for(int i=0;i<size;i++) {
			sum+=decodeHEX(hex[i]);
		}
		
		//取反转为16进制字符串
		String hex16=Integer.toHexString(~sum);
		
		//字符串的长度
		int lenth=hex16.length();		
		
		byte[] jiaoyan=hexStringToByteArray(hex16.substring(lenth-4, lenth));
		
		return jiaoyan;		
		
	}
	
	
	/**获取校验码除去包头相加取反*/
	public static String check2(String byt) {
		
		//字节数组转为16进制字符串/2后的长度
		int size=byt.length()/2;
		String[] hex=hex(byt);
		
		//求和
		int sum=0;
		for(int i=2;i<size-2;i++) {
			sum+=decodeHEX(hex[i]);
		}
		
		//取反转为16进制字符串
		String hex16=Integer.toHexString(~sum);
		
		//字符串的长度
		int lenth=hex16.length();		
		
		String jiaoyan=hex16.substring(lenth-4, lenth);
		
		return jiaoyan.toUpperCase();		
		
	}
	
	/**16进制转为10进制*/
	public static int decodeHEX(String hexs){
		BigInteger bigint=new BigInteger(hexs, 16);
		int numb=bigint.intValue();
		return numb;

	}
	
	/**将16进制字符串转为hex字符串数组2个字符串一个*/
	public static String[] hex(String message) {
		int size=message.length()/2;		
		String[] hex=new String[size];
		for(int i=0;i<size;i++) {
			hex[i]=message.substring(i*2, 2+i*2);
		}
		
		return hex;
	}
	
	
	/**将字节数组转换为16进制字符串无空格*/
	public static  String BinaryToHexString2(byte[] bytes) {
		String hexStr = "0123456789ABCDEF";
		String result = "";
		String hex = "";
		for (byte b : bytes) {
			hex = String.valueOf(hexStr.charAt((b & 0xF0) >> 4));
			hex += String.valueOf(hexStr.charAt(b & 0x0F));
			result += hex + "";
		}
		return result;
	}
	
	
	/**
     * 16进制表示的字符串转换为字节数组
    *
    * @param hexString 16进制表示的字符串
    * @return byte[] 字节数组
    */
   public static byte[] hexStringToByteArray(String hexString) {
       hexString = hexString.replaceAll(" ", "");
       int len = hexString.length();
       byte[] bytes = new byte[len / 2];
       for (int i = 0; i < len; i += 2) {
           // 两位一组，表示一个字节,把这样表示的16进制字符串，还原成一个字节
           bytes[i / 2] = (byte) ((Character.digit(hexString.charAt(i), 16) << 4) + Character
                   .digit(hexString.charAt(i+1), 16));
       }
       return bytes;
   }

}