.Net 获取文件的CRC32标识

public class FileToCRC32 {

        private static UInt32[] Crc32Table = { 
                                  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};

        /// <summary>
        /// 获取文件的CRC32标识
        /// </summary>
        /// <param name="filePath"></param>
        /// <returns></returns>
        public static String GetFileCRC32(String filePath) {
	        const string FOO = "-";
	        if (string.IsNullOrEmpty(filePath)) {
	        	return FOO;
	        }
			if (!File.Exists(filePath)) {
				return FOO;
			}

            // 最大50M
			const int MAX_SIZE = 50 * 1024 * 1024;
			var f = new FileInfo(filePath);
			if (f.Length >= MAX_SIZE) {
				return FOO;
			}

            UInt32 crc = 0xFFFFFFFF;
            var bin = File.ReadAllBytes(filePath);
            foreach(byte b in bin) {
                crc = ((crc >> 8) & 0x00FFFFFF) ^ Crc32Table[(crc ^ b) & 0xFF];
            }
            crc = crc ^ 0xFFFFFFFF;
            return crc.ToString("X");
        }
    }