crc校验算法java
CRC校验码的基本思想是利用线性编码理论，在发送端根据要传送的k位二进制码序列，以一定的规则产生一个校验用的监督码（既CRC码）r位，并附在信息后边，构成一个新的二进制码序列数共(k+r)位，最后发送出去。在接收端，则根据信息码和CRC码之间所遵循的规则进行检验，以确定传送中是否出错。
在数据存储和数据通讯领域，CRC无处不在:着名的通讯协议X.25的FCS(帧检错序列)采用的是CRC. CCITT，ARJ、LHA等压缩工具软件采用的是CRC32，磁盘驱动器的读写采用了CRC16，通用的图像存储格式GIF、TIFF等也都用CRC作为检错手段。
CRC的本质是模-2除法的余数，采用的除数不同，CRC的类型也就不一样。通常，CRC的除数用生成多项式来表示。最常用的CRC码的生成多项式有CRC16,CRC32.
以CRC16为例,16位的CRC码产生的规则是先将要发送的二进制序列数左移16位（既乘以2^16）后，再除以一个多项式，最后所得到的余数既是CRC码，如下式所示，其中K(X)表示n位的二进制序列数，G(X)为多项式，Q(X)为整数，R(X)是余数（既CRC码）。
K(X)>>16=G(x)Q(x)+R(x)
求CRC码所采用模2加减运算法则，既是不带进位和借位的按位加减，这种加减运算实际上就是逻辑上的异或运算，加法和减法等价，乘法和除法运算与普通代数式的乘除法运算是一样，符合同样的规律。生成CRC码的多项式如下，其中CRC-16和CRC-CCITT产生16位的CRC码，而CRC-32则产生的是32位的CRC码
接收方将接收到的二进制序列数（包括信息码和CRC码）除以多项式，如果余数为0，则说明传输中无错误发生，否则说明传输有误，关于其原理这里不再多述。用软件计算CRC码时，接收方可以将接收到的信息码求CRC码，比较结果和接收到的CRC码是否相同。
CCITT推荐的高级数据链路控制规程HDLC的帧校验序列FCS中，使用CCITT-16即CRC16,其生成多项式为G(x)=x16+x12+x5+1,CRC-32的生成多项式为G(x)=x32+x26+x23+x22+x16+x11+x10+x16+x8+x7+x5+x4+x2+x+1
2. crc校验求java到啊
public class CRC16 { public static String crc16(String src,int len){
int crc = 0x0000FFFF;
short tc;
char sbit;
for(int i=0;i<len; i++){
tc = (short)(crc >>>8);
crc = ((tc ^ src.charAt(i)) & 0x00FF); for(int r=0;r<8;r++){
sbit = (char)(crc & 0x01);
crc >>>= 1; //�1�7�1�7�1�7�0�6�1�7�1�7�1�7�1�7�1�7�1�7�1�7�0�5λ
if(sbit != 0)crc =(crc^0xA001) & 0x0000FFFF; }
}
//Integer.toHexString(crc);
return Integer.toHexString(crc);
}
}
3. 求java的 crc8算法方法
你的意思就翻译一下，是吗：
static char crc8fun ( char in, char prest)
{
int loop;
char out;
char crc_pol=0xb8; /*多项式*/
out = in^prest;
for(loop=0;loop<8;loop++){
if(out&0x01){
out=(out>>1)^crc_pol;
}else{
out=(out>>1);
}
return out;
}
}
4. CRC校验代码 c++ java都可以
不会，建议还是自己做吧。
5. 如何用java实现CRC8验证算法
/*http://www.koders.com/java/.aspx?s=Address#L34
*---------------------------------------------------------------------------
* Copyright (C) 1999,2000 Dallas Semiconctor Corporation, All Rights Reserved.
*
* Permission is hereby granted, free of charge, to any person obtaining a
* of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, , modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above right notice and this permission notice shall be included
* in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
* OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
* IN NO EVENT SHALL DALLAS SEMICONDUCTOR BE LIABLE FOR ANY CLAIM, DAMAGES
* OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
* ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
* OTHER DEALINGS IN THE SOFTWARE.
*
* Except as contained in this notice, the name of Dallas Semiconctor
* shall not be used except as stated in the Dallas Semiconctor
* Branding Policy.
*---------------------------------------------------------------------------
*/
package com.dalsemi.onewire.utils;
/**
* CRC8 is a class to contain an implementation of the
* Cyclic-Rendency-Check CRC8 for the iButton. The CRC8 is used
* in the 1-Wire Network address of all iButtons and 1-Wire
* devices.
* <p>
* CRC8 is based on the polynomial = X^8 + X^5 + X^4 + 1.
*
* @version 0.00, 28 Aug 2000
* @author DS
*
*/
public class CRC8
{
//--------
//-------- Variables
//--------
/**
* CRC 8 lookup table
*/
private static byte dscrc_table [];
/*
* Create the lookup table
*/
static
{
//Translated from the assembly code in iButton Standards, page 129.
dscrc_table = new byte [256];
int acc;
int crc;
for (int i = 0; i < 256; i++)
{
acc = i;
crc = 0;
for (int j = 0; j < 8; j++)
{
if (((acc ^ crc) & 0x01) == 0x01)
{
crc = ((crc ^ 0x18) >> 1) | 0x80;
}
else
crc = crc >> 1;
acc = acc >> 1;
}
dscrc_table [i] = ( byte ) crc;
}
}
//--------
//-------- Constructor
//--------
/**
* Private constructor to prevent instantiation.
*/
private CRC8 ()
{
}
//--------
//-------- Methods
//--------
/**
* Perform the CRC8 on the data element based on the provided seed.
* <p>
* CRC8 is based on the polynomial = X^8 + X^5 + X^4 + 1.
*
* @param dataToCrc data element on which to perform the CRC8
* @param seed seed the CRC8 with this value
* @return CRC8 value
*/
public static int compute (int dataToCRC, int seed)
{
return (dscrc_table [(seed ^ dataToCRC) & 0x0FF] & 0x0FF);
}
/**
* Perform the CRC8 on the data element based on a zero seed.
* <p>
* CRC8 is based on the polynomial = X^8 + X^5 + X^4 + 1.
*
* @param dataToCrc data element on which to perform the CRC8
* @return CRC8 value
*/
public static int compute (int dataToCRC)
{
return (dscrc_table [dataToCRC & 0x0FF] & 0x0FF);
}
/**
* Perform the CRC8 on an array of data elements based on a
* zero seed.
* <p>
* CRC8 is based on the polynomial = X^8 + X^5 + X^4 + 1.
*
* @param dataToCrc array of data elements on which to perform the CRC8
* @return CRC8 value
*/
public static int compute (byte dataToCrc [])
{
return compute(dataToCrc, 0, dataToCrc.length);
}
/**
* Perform the CRC8 on an array of data elements based on a
* zero seed.
* <p>
* CRC8 is based on the polynomial = X^8 + X^5 + X^4 + 1.
*
* @param dataToCrc array of data elements on which to perform the CRC8
* @param off offset into array
* @param len length of data to crc
* @return CRC8 value
*/
public static int compute (byte dataToCrc [], int off, int len)
{
return compute(dataToCrc, off, len, 0);
}
/**
* Perform the CRC8 on an array of data elements based on the
* provided seed.
* <p>
* CRC8 is based on the polynomial = X^8 + X^5 + X^4 + 1.
*
* @param dataToCrc array of data elements on which to perform the CRC8
* @param off offset into array
* @param len length of data to crc
* @param seed seed to use for CRC8
* @return CRC8 value
*/
public static int compute (byte dataToCrc [], int off, int len, int seed)
{
// loop to do the crc on each data element
int CRC8 = seed;
for (int i = 0; i < len; i++)
CRC8 = dscrc_table [(CRC8 ^ dataToCrc [i + off]) & 0x0FF];
return (CRC8 & 0x0FF);
}
/**
* Perform the CRC8 on an array of data elements based on the
* provided seed.
* <p>
* CRC8 is based on the polynomial = X^8 + X^5 + X^4 + 1.
*
* @param dataToCrc array of data elements on which to perform the CRC8
* @param seed seed to use for CRC8
* @return CRC8 value
*/
public static int compute (byte dataToCrc [], int seed)
{
return compute(dataToCrc, 0, dataToCrc.length, seed);
}
}
6. java 实现crc16校验算法的问题
貌似CRC算法循环求余时减法是不带借位的。
7. 求助，一段C的CRC校验算法，需要翻译成JAVA，感谢
publicstaticshortCRC16_WifiAllBtye(Numberdata,shortlen){
intcksum=0;
inttmp_32=0;
shorttmp_8=0;
shortp=data.shortValue();
if(data!=null){
while(len>1){
tmp_8=p++;
tmp_32=(int)(p++);
cksum+=tmp_32<<8;
cksum+=(int)tmp_8;
len-=2;
}
if(len>=0){
cksum+=(int)p;
}
cksum=(cksum>>16)+(cksum&0xFFFF);
cksum+=(cksum>>16);
}
return(short)(~cksum);
}
8. 用java实现一个CRC程序
强力围观，坐等高手回答！
9. 用java编写一个获得CRC校验码的javabean
private static String mkCrc16(String str) {
CRC16 crc16 = new CRC16();
byte[] b = str.getBytes();
for (int i = 0; i < b.length; i++)
crc16.update(b[i]);
return Integer.toHexString(crc16.value);
}
private static String mkCrc(String string) throws Exception {
CRC32 crc32 = new CRC32();
crc32.update(string.getBytes());
return Long.toHexString(crc32.getValue());
}
public class CRCUtil {
public static final int evalCRC16(byte[] data) {
int crc = 0xFFFF;
for (int i = 0; i < data.length; i++) {
crc = (data[i] << 8) ^ crc;
for (int j = 0; j < 8; ++j)
if ((crc & 0x8000) != 0)
crc = (crc << 1) ^ 0x1021;
else
crc <<= 1;
}
return (crc ^ 0xFFFF) & 0xFFFF;
}
}
10. JAVA怎么做CRC校验的程序
实现方法：最简单的校验就是把原始数据和待比较数据直接进行比较，看是否完全一样这种方法是最安全最准确的。同时也是效率最低的。
应用例子：龙珠cpu在线调试工具bbug.exe。它和龙珠cpu间通讯时，bbug发送一个字节cpu返回收到的字节，bbug确认是刚才发送字节后才继续发送下一个字节的。 实现方法：在数据存储和传输中，字节中额外增加一个比特位，用来检验错误。校验位可以通过数据位异或计算出来。
应用例子：单片机串口通讯有一模式就是8位数据通讯，另加第9位用于放校验值。
bcc异或校验法(block check character)
实现方法：很多基于串口的通讯都用这种既简单又相当准确的方法。它就是把所有数据都和一个指定的初始值（通常是0）异或一次，最后的结果就是校验值，通常把它附在通讯数据的最后一起发送出去。接收方收到数据后自己也计算一次异或和校验值，如果和收到的校验值一致就说明收到的数据是完整的。
校验值计算的代码类似于：
unsigned uCRC=0;//校验初始值
for(int i=0;i<DataLenth;i++) uCRC^=Data[i];
适用范围：适用于大多数要求不高的数据通讯。
应用例子：ic卡接口通讯、很多单片机系统的串口通讯都使用。 (Cyclic Rendancy Check)
实现方法：这是利用除法及余数的原理来进行错误检测的