CRC (Cyclic redundancy check) java 实现

CRC (Cyclic redundancy check) java 实现

CRC16
http://introcs.cs.princeton.edu/java/51data/CRC16.java

/**************************************************************************  Compilation:  javac CRC16.java*  Execution:    java CRC16 s*  *  Reads in a string s as a command-line argument, and prints out*  its 16-bit Cyclic Redundancy Check (CRC16). Uses a lookup table.**  Reference:  http://www.gelato.unsw.edu.au/lxr/source/lib/crc16.c**  % java CRC16 123456789*  CRC16 = bb3d** Uses irreducible polynomial:  1 + x^2 + x^15 + x^16***************************************************************************/public class CRC16 { public static void main(String[] args) { int[] table = {0x0000, 0xC0C1, 0xC181, 0x0140, 0xC301, 0x03C0, 0x0280, 0xC241,0xC601, 0x06C0, 0x0780, 0xC741, 0x0500, 0xC5C1, 0xC481, 0x0440,0xCC01, 0x0CC0, 0x0D80, 0xCD41, 0x0F00, 0xCFC1, 0xCE81, 0x0E40,0x0A00, 0xCAC1, 0xCB81, 0x0B40, 0xC901, 0x09C0, 0x0880, 0xC841,0xD801, 0x18C0, 0x1980, 0xD941, 0x1B00, 0xDBC1, 0xDA81, 0x1A40,0x1E00, 0xDEC1, 0xDF81, 0x1F40, 0xDD01, 0x1DC0, 0x1C80, 0xDC41,0x1400, 0xD4C1, 0xD581, 0x1540, 0xD701, 0x17C0, 0x1680, 0xD641,0xD201, 0x12C0, 0x1380, 0xD341, 0x1100, 0xD1C1, 0xD081, 0x1040,0xF001, 0x30C0, 0x3180, 0xF141, 0x3300, 0xF3C1, 0xF281, 0x3240,0x3600, 0xF6C1, 0xF781, 0x3740, 0xF501, 0x35C0, 0x3480, 0xF441,0x3C00, 0xFCC1, 0xFD81, 0x3D40, 0xFF01, 0x3FC0, 0x3E80, 0xFE41,0xFA01, 0x3AC0, 0x3B80, 0xFB41, 0x3900, 0xF9C1, 0xF881, 0x3840,0x2800, 0xE8C1, 0xE981, 0x2940, 0xEB01, 0x2BC0, 0x2A80, 0xEA41,0xEE01, 0x2EC0, 0x2F80, 0xEF41, 0x2D00, 0xEDC1, 0xEC81, 0x2C40,0xE401, 0x24C0, 0x2580, 0xE541, 0x2700, 0xE7C1, 0xE681, 0x2640,0x2200, 0xE2C1, 0xE381, 0x2340, 0xE101, 0x21C0, 0x2080, 0xE041,0xA001, 0x60C0, 0x6180, 0xA141, 0x6300, 0xA3C1, 0xA281, 0x6240,0x6600, 0xA6C1, 0xA781, 0x6740, 0xA501, 0x65C0, 0x6480, 0xA441,0x6C00, 0xACC1, 0xAD81, 0x6D40, 0xAF01, 0x6FC0, 0x6E80, 0xAE41,0xAA01, 0x6AC0, 0x6B80, 0xAB41, 0x6900, 0xA9C1, 0xA881, 0x6840,0x7800, 0xB8C1, 0xB981, 0x7940, 0xBB01, 0x7BC0, 0x7A80, 0xBA41,0xBE01, 0x7EC0, 0x7F80, 0xBF41, 0x7D00, 0xBDC1, 0xBC81, 0x7C40,0xB401, 0x74C0, 0x7580, 0xB541, 0x7700, 0xB7C1, 0xB681, 0x7640,0x7200, 0xB2C1, 0xB381, 0x7340, 0xB101, 0x71C0, 0x7080, 0xB041,0x5000, 0x90C1, 0x9181, 0x5140, 0x9301, 0x53C0, 0x5280, 0x9241,0x9601, 0x56C0, 0x5780, 0x9741, 0x5500, 0x95C1, 0x9481, 0x5440,0x9C01, 0x5CC0, 0x5D80, 0x9D41, 0x5F00, 0x9FC1, 0x9E81, 0x5E40,0x5A00, 0x9AC1, 0x9B81, 0x5B40, 0x9901, 0x59C0, 0x5880, 0x9841,0x8801, 0x48C0, 0x4980, 0x8941, 0x4B00, 0x8BC1, 0x8A81, 0x4A40,0x4E00, 0x8EC1, 0x8F81, 0x4F40, 0x8D01, 0x4DC0, 0x4C80, 0x8C41,0x4400, 0x84C1, 0x8581, 0x4540, 0x8701, 0x47C0, 0x4680, 0x8641,0x8201, 0x42C0, 0x4380, 0x8341, 0x4100, 0x81C1, 0x8081, 0x4040,};byte[] bytes = args[0].getBytes();int crc = 0x0000;for (byte b : bytes) {crc = (crc >>> 8) ^ table[(crc ^ b) & 0xff];}System.out.println("CRC16 = " + Integer.toHexString(crc));}}

CRC16CCITT
http://introcs.cs.princeton.edu/java/51data/CRC16CCITT.java

/**************************************************************************  Compilation:  javac CRC16CCITT.java*  Execution:    java CRC16CCITT s*  Dependencies: *  *  Reads in a sequence of bytes and prints out its 16 bit*  Cylcic Redundancy Check (CRC-CCIIT 0xFFFF).**  1 + x + x^5 + x^12 + x^16 is irreducible polynomial.**  % java CRC16-CCITT 123456789*  CRC16-CCITT = 29b1**************************************************************************/public class CRC16CCITT { public static void main(String[] args) { int crc = 0xFFFF;          // initial valueint polynomial = 0x1021;   // 0001 0000 0010 0001  (0, 5, 12) // byte[] testBytes = "123456789".getBytes("ASCII");byte[] bytes = args[0].getBytes();for (byte b : bytes) {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;System.out.println("CRC16-CCITT = " + Integer.toHexString(crc));}}

CRC32
http://introcs.cs.princeton.edu/java/51data/CRC32.java

/**************************************************************************  Compilation:  javac CRC32.java*  Execution:    java CRC32 s*  *  Reads in a string s as a command-line argument, and prints out*  its 32 bit Cyclic Redundancy Check (CRC32 or Ethernet / AAL5 or ITU-TSS).**  Uses direct table lookup, calculation, and Java library.**  % java CRC32 123456789*  CRC32 (via table lookup)       = cbf43926*  CRC32 (via direct calculation) = cbf43926*  CRC32 (via Java's library)     = cbf43926****  Uses irreducible polynomial:*     1    + x    + x^2  + x^4  + x^5  + x^7  + x^8  +*     x^10 + x^11 + x^12 + x^16 + x^22 + x^23 + x^26 **  0000 0100 1100 0001 0001 1101 1011 0111                 *   0    4    C    1    1    D    B    7**  The reverse of this polynomial is**   0    2    3    8    8    B    D    E****************************************************************************/public class CRC32 { public static void main(String[] args) { /***************************************************************************  Using table lookup*  Reference: http://snippets.dzone.com/tag/crc32**************************************************************************/int[] table = {0x00000000, 0x77073096, 0xee0e612c, 0x990951ba, 0x076dc419, 0x706af48f, 0xe963a535, 0x9e6495a3,0x0edb8832, 0x79dcb8a4, 0xe0d5e91e, 0x97d2d988, 0x09b64c2b, 0x7eb17cbd, 0xe7b82d07, 0x90bf1d91,0x1db71064, 0x6ab020f2, 0xf3b97148, 0x84be41de, 0x1adad47d, 0x6ddde4eb, 0xf4d4b551, 0x83d385c7,0x136c9856, 0x646ba8c0, 0xfd62f97a, 0x8a65c9ec, 0x14015c4f, 0x63066cd9, 0xfa0f3d63, 0x8d080df5,0x3b6e20c8, 0x4c69105e, 0xd56041e4, 0xa2677172, 0x3c03e4d1, 0x4b04d447, 0xd20d85fd, 0xa50ab56b,0x35b5a8fa, 0x42b2986c, 0xdbbbc9d6, 0xacbcf940, 0x32d86ce3, 0x45df5c75, 0xdcd60dcf, 0xabd13d59,0x26d930ac, 0x51de003a, 0xc8d75180, 0xbfd06116, 0x21b4f4b5, 0x56b3c423, 0xcfba9599, 0xb8bda50f,0x2802b89e, 0x5f058808, 0xc60cd9b2, 0xb10be924, 0x2f6f7c87, 0x58684c11, 0xc1611dab, 0xb6662d3d,0x76dc4190, 0x01db7106, 0x98d220bc, 0xefd5102a, 0x71b18589, 0x06b6b51f, 0x9fbfe4a5, 0xe8b8d433,0x7807c9a2, 0x0f00f934, 0x9609a88e, 0xe10e9818, 0x7f6a0dbb, 0x086d3d2d, 0x91646c97, 0xe6635c01,0x6b6b51f4, 0x1c6c6162, 0x856530d8, 0xf262004e, 0x6c0695ed, 0x1b01a57b, 0x8208f4c1, 0xf50fc457,0x65b0d9c6, 0x12b7e950, 0x8bbeb8ea, 0xfcb9887c, 0x62dd1ddf, 0x15da2d49, 0x8cd37cf3, 0xfbd44c65,0x4db26158, 0x3ab551ce, 0xa3bc0074, 0xd4bb30e2, 0x4adfa541, 0x3dd895d7, 0xa4d1c46d, 0xd3d6f4fb,0x4369e96a, 0x346ed9fc, 0xad678846, 0xda60b8d0, 0x44042d73, 0x33031de5, 0xaa0a4c5f, 0xdd0d7cc9,0x5005713c, 0x270241aa, 0xbe0b1010, 0xc90c2086, 0x5768b525, 0x206f85b3, 0xb966d409, 0xce61e49f,0x5edef90e, 0x29d9c998, 0xb0d09822, 0xc7d7a8b4, 0x59b33d17, 0x2eb40d81, 0xb7bd5c3b, 0xc0ba6cad,0xedb88320, 0x9abfb3b6, 0x03b6e20c, 0x74b1d29a, 0xead54739, 0x9dd277af, 0x04db2615, 0x73dc1683,0xe3630b12, 0x94643b84, 0x0d6d6a3e, 0x7a6a5aa8, 0xe40ecf0b, 0x9309ff9d, 0x0a00ae27, 0x7d079eb1,0xf00f9344, 0x8708a3d2, 0x1e01f268, 0x6906c2fe, 0xf762575d, 0x806567cb, 0x196c3671, 0x6e6b06e7,0xfed41b76, 0x89d32be0, 0x10da7a5a, 0x67dd4acc, 0xf9b9df6f, 0x8ebeeff9, 0x17b7be43, 0x60b08ed5,0xd6d6a3e8, 0xa1d1937e, 0x38d8c2c4, 0x4fdff252, 0xd1bb67f1, 0xa6bc5767, 0x3fb506dd, 0x48b2364b,0xd80d2bda, 0xaf0a1b4c, 0x36034af6, 0x41047a60, 0xdf60efc3, 0xa867df55, 0x316e8eef, 0x4669be79,0xcb61b38c, 0xbc66831a, 0x256fd2a0, 0x5268e236, 0xcc0c7795, 0xbb0b4703, 0x220216b9, 0x5505262f,0xc5ba3bbe, 0xb2bd0b28, 0x2bb45a92, 0x5cb36a04, 0xc2d7ffa7, 0xb5d0cf31, 0x2cd99e8b, 0x5bdeae1d,0x9b64c2b0, 0xec63f226, 0x756aa39c, 0x026d930a, 0x9c0906a9, 0xeb0e363f, 0x72076785, 0x05005713,0x95bf4a82, 0xe2b87a14, 0x7bb12bae, 0x0cb61b38, 0x92d28e9b, 0xe5d5be0d, 0x7cdcefb7, 0x0bdbdf21,0x86d3d2d4, 0xf1d4e242, 0x68ddb3f8, 0x1fda836e, 0x81be16cd, 0xf6b9265b, 0x6fb077e1, 0x18b74777,0x88085ae6, 0xff0f6a70, 0x66063bca, 0x11010b5c, 0x8f659eff, 0xf862ae69, 0x616bffd3, 0x166ccf45,0xa00ae278, 0xd70dd2ee, 0x4e048354, 0x3903b3c2, 0xa7672661, 0xd06016f7, 0x4969474d, 0x3e6e77db,0xaed16a4a, 0xd9d65adc, 0x40df0b66, 0x37d83bf0, 0xa9bcae53, 0xdebb9ec5, 0x47b2cf7f, 0x30b5ffe9,0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6, 0xbad03605, 0xcdd70693, 0x54de5729, 0x23d967bf,0xb3667a2e, 0xc4614ab8, 0x5d681b02, 0x2a6f2b94, 0xb40bbe37, 0xc30c8ea1, 0x5a05df1b, 0x2d02ef8d,};byte[] bytes = args[0].getBytes();int crc = 0xffffffff;for (byte b : bytes) {crc = (crc >>> 8) ^ table[(crc ^ b) & 0xff];}// flip bitscrc = crc ^ 0xffffffff;System.out.println("CRC32 (via table lookup)       = " + Integer.toHexString(crc));/***************************************************************************  Using direct calculation**************************************************************************/crc  = 0xFFFFFFFF;       // initial contents of LFBSRint poly = 0xEDB88320;   // reverse polynomialfor (byte b : bytes) {int temp = (crc ^ b) & 0xff;// read 8 bits one at a timefor (int i = 0; i < 8; i++) {if ((temp & 1) == 1) temp = (temp >>> 1) ^ poly;else                 temp = (temp >>> 1);}crc = (crc >>> 8) ^ temp;}// flip bitscrc = crc ^ 0xffffffff;System.out.println("CRC32 (via direct calculation) = " + Integer.toHexString(crc));/***************************************************************************  Using Java's java.util.zip.CRC32 library**************************************************************************/java.util.zip.CRC32 x = new java.util.zip.CRC32();x.update(bytes);System.out.println("CRC32 (via Java's library)     = " + Long.toHexString(x.getValue()));}}

文件CRC 32
http://www.javafaq.nu/java-example-code-230.html

// -----------------------------------------------------------------------------
// ChecksumCRC32.java
// -----------------------------------------------------------------------------/** =============================================================================* Copyright (c) 1998-2005 Jeffrey M. Hunter. All rights reserved.** All source code and material located at the Internet address of* http://www.idevelopment.info is the copyright of Jeffrey M. Hunter, 2005 and* is protected under copyright laws of the United States. This source code may* not be hosted on any other site without my express, prior, written* permission. Application to host any of the material elsewhere can be made by* contacting me at jhunter@idevelopment.info.** I have made every effort and taken great care in making sure that the source* code and other content included on my web site is technically accurate, but I* disclaim any and all responsibility for any loss, damage or destruction of* data or any other property which may arise from relying on it. I will in no* case be liable for any monetary damages arising from such loss, damage or* destruction.** As with any code, ensure to test this code in a development environment* before attempting to run it in production.* =============================================================================*/import java.util.zip.CheckedInputStream;
import java.util.zip.CRC32;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;/*** -----------------------------------------------------------------------------* Used to provide an example of how to calculate the checksum of a file using* the CRC-32 checksum engine.** @version 1.0* @author  Jeffrey M. Hunter  (jhunter@idevelopment.info)* @author  http://www.idevelopment.info* -----------------------------------------------------------------------------*/public class ChecksumCRC32 {private static void doChecksum(String fileName) {try {CheckedInputStream cis = null;long fileSize = 0;try {// Computer CRC32 checksumcis = new CheckedInputStream(new FileInputStream(fileName), new CRC32());fileSize = new File(fileName).length();} catch (FileNotFoundException e) {System.err.println("File not found.");System.exit(1);}byte[] buf = new byte[128];while(cis.read(buf) >= 0) {}long checksum = cis.getChecksum().getValue();System.out.println(checksum + " " + fileSize + " " + fileName);} catch (IOException e) {e.printStackTrace();System.exit(1);}}/*** Sole entry point to the class and application.* @param args Array of String arguments.*/public static void main(String[] args) {if (args.length != 1) {System.err.println("Usage: java ChecksumCRC32 filename");} else {doChecksum(args[0]);}}}

文件CRC查表方式，效率高于CheckedInputStream

import java.io.BufferedInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;/*** file crc32* * @author berry*/
public class FileCRC32 {/*** @param args*/public static void main(String[] args) {/*************************************************************************** Using table lookup Reference: http://snippets.dzone.com/tag/crc32**************************************************************************/int[] table = { 0x00000000, 0x77073096, 0xee0e612c, 0x990951ba,0x076dc419, 0x706af48f, 0xe963a535, 0x9e6495a3, 0x0edb8832,0x79dcb8a4, 0xe0d5e91e, 0x97d2d988, 0x09b64c2b, 0x7eb17cbd,0xe7b82d07, 0x90bf1d91, 0x1db71064, 0x6ab020f2, 0xf3b97148,0x84be41de, 0x1adad47d, 0x6ddde4eb, 0xf4d4b551, 0x83d385c7,0x136c9856, 0x646ba8c0, 0xfd62f97a, 0x8a65c9ec, 0x14015c4f,0x63066cd9, 0xfa0f3d63, 0x8d080df5, 0x3b6e20c8, 0x4c69105e,0xd56041e4, 0xa2677172, 0x3c03e4d1, 0x4b04d447, 0xd20d85fd,0xa50ab56b, 0x35b5a8fa, 0x42b2986c, 0xdbbbc9d6, 0xacbcf940,0x32d86ce3, 0x45df5c75, 0xdcd60dcf, 0xabd13d59, 0x26d930ac,0x51de003a, 0xc8d75180, 0xbfd06116, 0x21b4f4b5, 0x56b3c423,0xcfba9599, 0xb8bda50f, 0x2802b89e, 0x5f058808, 0xc60cd9b2,0xb10be924, 0x2f6f7c87, 0x58684c11, 0xc1611dab, 0xb6662d3d,0x76dc4190, 0x01db7106, 0x98d220bc, 0xefd5102a, 0x71b18589,0x06b6b51f, 0x9fbfe4a5, 0xe8b8d433, 0x7807c9a2, 0x0f00f934,0x9609a88e, 0xe10e9818, 0x7f6a0dbb, 0x086d3d2d, 0x91646c97,0xe6635c01, 0x6b6b51f4, 0x1c6c6162, 0x856530d8, 0xf262004e,0x6c0695ed, 0x1b01a57b, 0x8208f4c1, 0xf50fc457, 0x65b0d9c6,0x12b7e950, 0x8bbeb8ea, 0xfcb9887c, 0x62dd1ddf, 0x15da2d49,0x8cd37cf3, 0xfbd44c65, 0x4db26158, 0x3ab551ce, 0xa3bc0074,0xd4bb30e2, 0x4adfa541, 0x3dd895d7, 0xa4d1c46d, 0xd3d6f4fb,0x4369e96a, 0x346ed9fc, 0xad678846, 0xda60b8d0, 0x44042d73,0x33031de5, 0xaa0a4c5f, 0xdd0d7cc9, 0x5005713c, 0x270241aa,0xbe0b1010, 0xc90c2086, 0x5768b525, 0x206f85b3, 0xb966d409,0xce61e49f, 0x5edef90e, 0x29d9c998, 0xb0d09822, 0xc7d7a8b4,0x59b33d17, 0x2eb40d81, 0xb7bd5c3b, 0xc0ba6cad, 0xedb88320,0x9abfb3b6, 0x03b6e20c, 0x74b1d29a, 0xead54739, 0x9dd277af,0x04db2615, 0x73dc1683, 0xe3630b12, 0x94643b84, 0x0d6d6a3e,0x7a6a5aa8, 0xe40ecf0b, 0x9309ff9d, 0x0a00ae27, 0x7d079eb1,0xf00f9344, 0x8708a3d2, 0x1e01f268, 0x6906c2fe, 0xf762575d,0x806567cb, 0x196c3671, 0x6e6b06e7, 0xfed41b76, 0x89d32be0,0x10da7a5a, 0x67dd4acc, 0xf9b9df6f, 0x8ebeeff9, 0x17b7be43,0x60b08ed5, 0xd6d6a3e8, 0xa1d1937e, 0x38d8c2c4, 0x4fdff252,0xd1bb67f1, 0xa6bc5767, 0x3fb506dd, 0x48b2364b, 0xd80d2bda,0xaf0a1b4c, 0x36034af6, 0x41047a60, 0xdf60efc3, 0xa867df55,0x316e8eef, 0x4669be79, 0xcb61b38c, 0xbc66831a, 0x256fd2a0,0x5268e236, 0xcc0c7795, 0xbb0b4703, 0x220216b9, 0x5505262f,0xc5ba3bbe, 0xb2bd0b28, 0x2bb45a92, 0x5cb36a04, 0xc2d7ffa7,0xb5d0cf31, 0x2cd99e8b, 0x5bdeae1d, 0x9b64c2b0, 0xec63f226,0x756aa39c, 0x026d930a, 0x9c0906a9, 0xeb0e363f, 0x72076785,0x05005713, 0x95bf4a82, 0xe2b87a14, 0x7bb12bae, 0x0cb61b38,0x92d28e9b, 0xe5d5be0d, 0x7cdcefb7, 0x0bdbdf21, 0x86d3d2d4,0xf1d4e242, 0x68ddb3f8, 0x1fda836e, 0x81be16cd, 0xf6b9265b,0x6fb077e1, 0x18b74777, 0x88085ae6, 0xff0f6a70, 0x66063bca,0x11010b5c, 0x8f659eff, 0xf862ae69, 0x616bffd3, 0x166ccf45,0xa00ae278, 0xd70dd2ee, 0x4e048354, 0x3903b3c2, 0xa7672661,0xd06016f7, 0x4969474d, 0x3e6e77db, 0xaed16a4a, 0xd9d65adc,0x40df0b66, 0x37d83bf0, 0xa9bcae53, 0xdebb9ec5, 0x47b2cf7f,0x30b5ffe9, 0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6,0xbad03605, 0xcdd70693, 0x54de5729, 0x23d967bf, 0xb3667a2e,0xc4614ab8, 0x5d681b02, 0x2a6f2b94, 0xb40bbe37, 0xc30c8ea1,0x5a05df1b, 0x2d02ef8d, };FileInputStream fis = null;BufferedInputStream bis = null;int BUFFER_SIZE = 1024;byte[] buf = new byte[BUFFER_SIZE];int crc = 0xffffffff;try {File file = new File("crc32.txt");fis = new FileInputStream(file);bis = new BufferedInputStream(fis);int num;byte b;while ((num = bis.read(buf)) >= 0) {for (int i = 0; i < num; i++) {b = buf[i];crc = (crc >>> 8) ^ table[(crc ^ b) & 0xff];}}} catch (FileNotFoundException e) {e.printStackTrace();} catch (IOException e) {e.printStackTrace();} finally {if (fis != null) {try {fis.close();} catch (IOException e) {e.printStackTrace();}}if (bis != null) {try {bis.close();} catch (IOException e) {e.printStackTrace();}}}// flip bitscrc = crc ^ 0xffffffff;System.out.println("file CRC32 (via table lookup)       = "+ Integer.toHexString(crc));}}

生成码表代码

/*** build crc32 table* * @author berry*/
public class T1 {/*** @param args*/public static void main(String[] args) {// buildCrc32Table();make_crc_table();}public static void buildCrc32Table() {// This is the official polynomial used by CRC-32// in PKZip, WinZip and Ethernet.int ulPolynomial = 0x04C11DB7;int[] table = new int[0xFF + 1];// 256 values representing ASCII character codes.for (int i = 0; i <= 0xFF; i++) {table[i] = reflect(i, 8) << 24;for (int j = 0; j < 8; j++) {table[i] = (table[i] << 1)^ ((table[i] & (1 << 31)) != 0 ? ulPolynomial : 0);}table[i] = reflect(table[i], 32);System.out.println(String.format("0x%08x", table[i]));}}public static int reflect(int ref, int ch) {int value = 0;// Swap bit 0 for bit 7// bit 1 for bit 6, etc.for (int i = 1; i < (ch + 1); i++) {if ((ref & 1) != 0) {value |= 1 << (ch - i);}ref >>= 1;}return value;}public static void make_crc_table() {final int CRC32_POLYNOMIAL = 0xEDB88320;int i, j;int crc;int[] CRCTable = new int[256];for (i = 0; i <= 255; i++) {crc = i;for (j = 8; j > 0; j--) {if ((crc & 1) == 1) {crc = (crc >>> 1) ^ CRC32_POLYNOMIAL;} else {crc >>>= 1;}}System.out.println(String.format("0x%08x", crc));CRCTable[i] = crc;}}
}

参考资料：
[1] rfc1952, GZIP file format specification version 4.3. http://www.ietf.org/rfc/rfc1952
[2] ITU-T recommendation V.42. http://www.itu.int/rec/T-REC-V.42-200203-I/en
[3] Introduction to Programming in Java, 5.1 Data Representations. http://introcs.cs.princeton.edu/java/51data/
[4] CRC-32 implementation in java.util.zip.CRC32. http://stackoverflow.com/questions/9004016/crc-32-implementation-in-java-util-zip-crc32
[5] Calculating the Checksum of a File / CRC-32 Java code example. http://www.javafaq.nu/java-example-code-230.html
[6] CRC32  Algorithms. http://www.codeproject.com/Articles/1444/CRC_32
[7] CRC32 calculation. http://www.axlradius.com/freestuff/CRC32.java