摘要：
CRC-16 CCITT-FALSE格式校验函数 CRC-16校验产生2个字节长度的数据校验码，通过计算得到的校验码和获得的校验码比较，用于验证... CRC-16 CCITT-FALSE格式校验函数
CRC-16校验产生2个字节长度的数据校验码，通过计算得到的校验码和获得的校验码比较，用于验证获得的数据的正确性。基本的CRC-16校验算法实现。同应用规范通过对输入数据前处理和输出数据后处理的方式不同，又产生了不同的应用规范校验函数，这里介绍CCITT-FALSE格式的CRC-16校验函数。CCITT-FALSE格式对输入数据，预置值为0XFFFF（当做最初的余数）。
这里分享java实现crc_16_CCITT_False核验码算法工具类
代码：
package com.tehn.utils;
/**
* @Desc: Crc16进制工具类
* @Author：DurkBlue
* @Package：com.tehn.utils
* @Project：meteorology-six-elements
* @name：Crc16Utils
* @Date：2024/7/23 0023 15:34
* @Filename：Crc16Utils
*/
public class Crc16Utils {
/**
* CRC-16/CCITT-FALSE x16+x12+x5+1 算法
*
* info
* Name:CRC-16/CCITT-FAI
* Width:16
* Poly:0x1021
* Init:0xFFFF
* RefIn:False
* RefOut:False
* XorOut:0x0000
*
* @param hexString
* @param
* @return
*/
public static String crc_16_CCITT_False(String hexString) {
byte[] destByte = new byte[hexString.length()/2];
int j=0;
for(int i=0;i<destByte.length;i++) {
byte high = (byte) (Character.digit(hexString.charAt(j), 16) & 0xff);
byte low = (byte) (Character.digit(hexString.charAt(j + 1), 16) & 0xff);
destByte[i] = (byte) (high << 4 | low);
j+=2;
}
int crc = 0xffff; // 初始值
int polynomial = 0x1021; // 聚合值
for (int index = 0; index < destByte.length; index++) {
byte b = destByte[index];
for (int i = 0; i < 8; i++) {
boolean bit = ((b >> (7 - i) & 1) == 1);
boolean c15 = ((crc >> 15 & 1) == 1);
crc <<= 1;
if (c15 ^ bit)
crc ^= polynomial;
}
}
crc &= 0xffff;
String strCrc = Integer.toHexString(crc).toUpperCase();
return strCrc;
}
}
java实现modbus CRC的计算方法一
package cn.tehn.util;
public class CrcUtil {
private static char[] HEX_VOCABLE = new char[]{'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F'};
public static void main(String[] args) {
String hexString = "020358449118d14492c004448d6c604492139a4496da2e449683f9447eddb8447aa437364c83a835af507535af507535af507535af507535af507535af50754e8834a94d8e60744a8b70344bd9cbf04d99c2fe4a2a13ef41bdb935";
String hex = "02030A00002C";
System.out.println(crc_16_CCITT_False(hexString));
System.out.println(crc16B(hexToBytes(hexString)));
System.out.println(crc_16_modbus(hex));
System.out.println(crc_16_modbus(hexString));
}
private static int indexOf(String input, char c) {
for(int i = 0; i < HEX_VOCABLE.length; ++i) {
if (c == HEX_VOCABLE[i]) {
return i;
}
}
throw new IllegalArgumentException("err input:" + input);
}
public static byte[] hexToBytes(String hex) {
if (hex.length() % 2 != 0) {
throw new IllegalArgumentException("input string should be any multiple of 2!");
} else {
hex.toUpperCase();
byte[] byteBuffer = new byte[hex.length() / 2];
byte padding = 0;
boolean paddingTurning = false;
for(int i = 0; i < hex.length(); ++i) {
char c;
int index;
if (paddingTurning) {
c = hex.charAt(i);
index = indexOf(hex, c);
padding = (byte)(padding << 4 | index);
byteBuffer[i / 2] = padding;
padding = 0;
paddingTurning = false;
} else {
c = hex.charAt(i);
index = indexOf(hex, c);
padding = (byte)(padding | index);
paddingTurning = true;
}
}
return byteBuffer;
}
}
/**
* 增加modbus的CRC低位在前高位在后的校验位后发送
*
* @param message
* @return
*/
public static String addModbusCrc(String message) {
String messageToSend = message + CrcUtil.crc_16_modbus(message);
return messageToSend;
}
/**
* 计算Modbus CRC-16
*
* @param hexString
* @return
*/
public static String crc_16_modbus(String hexString) {
// Modbus CRC-16生成多项式，x^16 + x^15 + x^2 + 1
int POLYNOMIAL = 0xA001;
// 将十六进制字符串转换为字节数组
byte[] bytes = hexToBytes(hexString);
// 初始CRC寄存器值
int crc = 0xFFFF;
// 对每个字节进行处理
for (byte b : bytes) {
crc ^= b & 0xFF; // 字节与CRC寄存器进行异或
for (int i = 8; i != 0; i--) {
if ((crc & 0x0001) != 0) { // 如果最低位为1
crc >>= 1; // 右移一位
crc ^= POLYNOMIAL; // 与多项式进行异或
} else { // 如果最低位为0
crc >>= 1; // 右移一位
}
}
}
// 返回CRC的十六进制字符串表示，不带前缀"0x"
String crcString = String.format("%04x", crc & 0xFFFF);
//处理大小端翻转的情况,CRC校验码低位在前，高位在后
crcString = flipCRC(crcString);
return crcString;
}
/**
* 处理大小端翻转的情况,CRC校验码低位在前，高位在后
*
* @param crc
* @return
*/
private static String flipCRC(String crc) {
// 检查输入的CRC长度，假设为4位，可以根据实际情况进行调整
if (crc.length() != 4) {
throw new IllegalArgumentException("CRC应为4位长度");
}
// 翻转CRC码
StringBuilder flipped = new StringBuilder();
flipped.append(crc.charAt(2)).append(crc.charAt(3)).append(crc.charAt(0)).append(crc.charAt(1));
return flipped.toString();
}
private static int[] table = {
0x0000, 0x1021, 0x2042, 0x3063, 0x4084, 0x50A5, 0x60C6, 0x70E7,
0x8108, 0x9129, 0xA14A, 0xB16B, 0xC18C, 0xD1AD, 0xE1CE, 0xF1EF,
0x1231, 0x0210, 0x3273, 0x2252, 0x52B5, 0x4294, 0x72F7, 0x62D6,
0x9339, 0x8318, 0xB37B, 0xA35A, 0xD3BD, 0xC39C, 0xF3FF, 0xE3DE,
0x2462, 0x3443, 0x0420, 0x1401, 0x64E6, 0x74C7, 0x44A4, 0x5485,
0xA56A, 0xB54B, 0x8528, 0x9509, 0xE5EE, 0xF5CF, 0xC5AC, 0xD58D,
0x3653, 0x2672, 0x1611, 0x0630, 0x76D7, 0x66F6, 0x5695, 0x46B4,
0xB75B, 0xA77A, 0x9719, 0x8738, 0xF7DF, 0xE7FE, 0xD79D, 0xC7BC,
0x48C4, 0x58E5, 0x6886, 0x78A7, 0x0840, 0x1861, 0x2802, 0x3823,
0xC9CC, 0xD9ED, 0xE98E, 0xF9AF, 0x8948, 0x9969, 0xA90A, 0xB92B,
0x5AF5, 0x4AD4, 0x7AB7, 0x6A96, 0x1A71, 0x0A50, 0x3A33, 0x2A12,
0xDBFD, 0xCBDC, 0xFBBF, 0xEB9E, 0x9B79, 0x8B58, 0xBB3B, 0xAB1A,
0x6CA6, 0x7C87, 0x4CE4, 0x5CC5, 0x2C22, 0x3C03, 0x0C60, 0x1C41,
0xEDAE, 0xFD8F, 0xCDEC, 0xDDCD, 0xAD2A, 0xBD0B, 0x8D68, 0x9D49,
0x7E97, 0x6EB6, 0x5ED5, 0x4EF4, 0x3E13, 0x2E32, 0x1E51, 0x0E70,
0xFF9F, 0xEFBE, 0xDFDD, 0xCFFC, 0xBF1B, 0xAF3A, 0x9F59, 0x8F78,
0x9188, 0x81A9, 0xB1CA, 0xA1EB, 0xD10C, 0xC12D, 0xF14E, 0xE16F,
0x1080, 0x00A1, 0x30C2, 0x20E3, 0x5004, 0x4025, 0x7046, 0x6067,
0x83B9, 0x9398, 0xA3FB, 0xB3DA, 0xC33D, 0xD31C, 0xE37F, 0xF35E,
0x02B1, 0x1290, 0x22F3, 0x32D2, 0x4235, 0x5214, 0x6277, 0x7256,
0xB5EA, 0xA5CB, 0x95A8, 0x8589, 0xF56E, 0xE54F, 0xD52C, 0xC50D,
0x34E2, 0x24C3, 0x14A0, 0x0481, 0x7466, 0x6447, 0x5424, 0x4405,
0xA7DB, 0xB7FA, 0x8799, 0x97B8, 0xE75F, 0xF77E, 0xC71D, 0xD73C,
0x26D3, 0x36F2, 0x0691, 0x16B0, 0x6657, 0x7676, 0x4615, 0x5634,
0xD94C, 0xC96D, 0xF90E, 0xE92F, 0x99C8, 0x89E9, 0xB98A, 0xA9AB,
0x5844, 0x4865, 0x7806, 0x6827, 0x18C0, 0x08E1, 0x3882, 0x28A3,
0xCB7D, 0xDB5C, 0xEB3F, 0xFB1E, 0x8BF9, 0x9BD8, 0xABBB, 0xBB9A,
0x4A75, 0x5A54, 0x6A37, 0x7A16, 0x0AF1, 0x1AD0, 0x2AB3, 0x3A92,
0xFD2E, 0xED0F, 0xDD6C, 0xCD4D, 0xBDAA, 0xAD8B, 0x9DE8, 0x8DC9,
0x7C26, 0x6C07, 0x5C64, 0x4C45, 0x3CA2, 0x2C83, 0x1CE0, 0x0CC1,
0xEF1F, 0xFF3E, 0xCF5D, 0xDF7C, 0xAF9B, 0xBFBA, 0x8FD9, 0x9FF8,
0x6E17, 0x7E36, 0x4E55, 0x5E74, 0x2E93, 0x3EB2, 0x0ED1, 0x1EF0
};
public static String crc16B(byte[] bytes) {
int crc = 0xFFFF;
for (byte b : bytes) {
char ch = (char) (b & 0xFF);
crc = ((crc << 8) & 0xFF00) ^ table[((crc >> 8) & 0xFF) ^ ch];
}
return String.format("%04x", crc);
}
/**
* CRC-16/CCITT-FALSE x16+x12+x5+1 算法
* <p>
* info
* Name:CRC-16/CCITT-FAI
* Width:16
* Poly:0x1021
* Init:0xFFFF
* RefIn:False
* RefOut:False
* XorOut:0x0000
*
* @param hexString
* @param
* @return
*/
public static String crc_16_CCITT_False(String hexString) {
byte[] destByte = new byte[hexString.length() / 2];
int j = 0;
for (int i = 0; i < destByte.length; i++) {
byte high = (byte) (Character.digit(hexString.charAt(j), 16) & 0xff);
byte low = (byte) (Character.digit(hexString.charAt(j + 1), 16) & 0xff);
destByte[i] = (byte) (high << 4 | low);
j += 2;
}
int crc = 0xffff; // initial value
int polynomial = 0x1021; // poly value
for (int index = 0; index < destByte.length; index++) {
byte b = destByte[index];
for (int i = 0; i < 8; i++) {
boolean bit = ((b >> (7 - i) & 1) == 1);
boolean c15 = ((crc >> 15 & 1) == 1);
crc <<= 1;
if (c15 ^ bit)
crc ^= polynomial;
}
}
crc &= 0xffff;
String strCrc = Integer.toHexString(crc).toUpperCase();
return strCrc;
}
}第二种方法实现CRC_16/MODBUS 算法
package com.tehn.utils;
import org.apache.commons.lang3.StringUtils;
/**
* @Desc: Crc16进制工具类实现CRC-16/MODBUS算法
* @Author：DurkBlue
* @Package：com.tehn.utils
* @Project：meteorology-six-elements
* @name：Crc16Utils
* @Date：2024/7/23 0023 15:34
* @Filename：Crc16Utils
*/
public class Crc16Utils {
private static final Integer ONE = 1;
private static final Integer TWO = 2;
private static final Integer HEX = 16;
private static final String NUL = "";
private static final String SPACE = " ";
private static final String ASCII = "US-ASCII";
/**
* 根据报文byte数组，获取CRC-16 16进制字符串<p>
* 48 4C 01 00 01 00 00 05 00 00 >> 0xE647
*
* @param data 报文数组
* @return CRC值（16进制）
*/
public static String getCrc16HexStr(String data) {
return crcToHexStr(getCrc16(data));
}
/**
* 根据报文byte数组，获取CRC-16 int值<p>
* 48 4C 01 00 01 00 00 05 00 00 >> 58951
*
* @param data 报文数组
* @return CRC值（10进制）
*/
public static int getCrc16(String data) {
if (StringUtils.isBlank(data)) {
// ----- 校验：报文字符串不能为空，否则抛异常
throw new RuntimeException("The string cannot be empty!");
}
return getCrc16(hexStrToByteArr(data));
}
/**
* 根据报文byte数组，获取CRC-16 16进制字符串<p>
* {0x48, 0x4C, 0x01, 0x00, 0x01, 0x00, 0x00, 0x05, 0x00, 0x00} >> 0xE647
*
* @param data 报文数组
* @return CRC值（16进制）
*/
public static String getCrc16HexStr(byte[] data) {
return crcToHexStr(getCrc16(data));
}
/**
* 根据报文byte数组，获取CRC-16 int值<p>
* {0x48, 0x4C, 0x01, 0x00, 0x01, 0x00, 0x00, 0x05, 0x00, 0x00} >> 58951
*
* @param data 报文数组
* @return CRC值（10进制）
*/
public static int getCrc16(byte[] data) {
if (data.length == 0) {
// ----- 校验：报文数组不能为空，否则抛异常
throw new RuntimeException("The array cannot be empty!");
}
// ----- 预置一个CRC寄存器，初始值为0xFFFF
int crc = 0xFFFF;
byte byteLen;
boolean flag;
for (byte item : data) {
// ----- 循环，将每数据帧中的每个字节与CRC寄存器中的低字节进行异或运算
crc ^= ((int) item & 0x00FF);
byteLen = 8;
while (byteLen > 0) {
// ----- 判断寄存器最后一位是 1\0：[true: 1; false: 0]
flag = (crc & ONE) == ONE;
// ----- 将寄存器右移1位，最高位自动补0
crc >>= 1;
if (flag) {
// ----- 如果右移出来的位是 1：将寄存器与固定值 0xA001 异或运算
// ----- 如果右移出来的位是 0：不做处理，进行下一次右移
// ----- 直到处理完整个字节的8位
crc ^= 0xA001;
}
byteLen--;
}
}
// ----- 最终寄存器得值就是CRC的值，返回
return crc;
}
/**
* 将16进制字符串转换为16进制Byte数组<p>
* 48 4C 01 00 01 00 00 05 00 00 >> {0x48, 0x4C, 0x01, 0x00, 0x01, 0x00, 0x00, 0x05, 0x00, 0x00}
*
* @param str 报文字符串
* @return 报文数组
*/
private static byte[] hexStrToByteArr(String str) {
str = str.replaceAll(SPACE, NUL);
int strLen = str.length();
if ((strLen & ONE) == ONE) {
// ----- 报文字符串必须是以一个字节为单位（两位为一个字节），所以当去除所有空格后的报文长度为单数时说明报文错误
throw new RuntimeException("Incorrect message format!");
}
byte[] result = new byte[strLen / TWO];
// ----- 两位一个字节
for (int i = 0; i < strLen; i += TWO) {
String temp = str.substring(i, i + TWO);
result[i / TWO] = (byte) Integer.parseInt(temp, HEX);
}
return result;
}
/**
* 将CRC-16值转换成16进制字符串，且保持最小长度为4位<p>
* 58951 >> E647
*
* @param data CRC值（10进制）
* @return CRC值（16进制）
*/
private static String crcToHexStr(int data) {
String crcStr = Integer.toHexString(data).toUpperCase();
int size = 4 - crcStr.length();
StringBuilder builder = new StringBuilder();
// ---- 长度不够 4 位高位自动补0
while (size > 0) {
builder.append("0");
size--;
}
return builder.append(crcStr).toString();
}
/**
* 输出16进制与长度, 提供给 C++ CRC校验方法 测试 代码使用
*
* @param str 16进制字符串
*/
public static void printHexStr(String str) {
String[] split = str.split(SPACE);
StringBuilder builder = new StringBuilder();
builder.append(" unsigned char arr[] = {");
for (int i = 0; i < split.length; i++) {
builder.append("0x").append(split[i]);
if (i < split.length - 1) {
builder.append(", ");
}
}
builder.append("};");
System.out.println(builder.toString());
System.out.println(" int len = " + split.length + ";");
}
}
![SpringCloud 连接RabbitMQ 显示Socket Closed Attempting to connect to: [localhost:15672] 连接被拒](https://hepuhua.cn/zb_users/upload/2024/01/202401261706243723695160.png)
