c 写文件编码（文本文件编码识别）

前言

C#中识别文件的编码是一个头疼的问题，最近在做导入微信商户后台退款数据时，无论怎么设置编码导出来都是乱码，后来在网上找了这个识别文件编码的代码，感觉不错。最后识别出来是gb2312，看来我还是太渣了，只能吃土了，竟然忘记了这个编码。

下面话不多说，上代码。

123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187 /// <summary> /// 用于取得一个文本文件的编码方式(Encoding)。 /// </summary> public class TxtFileEncoder{public TxtFileEncoder(){// // TODO: 在此处添加构造函数逻辑 // }/// <summary> /// 取得一个文本文件的编码方式。如果无法在文件头部找到有效的前导符，Encoding.Default将被返回。 /// </summary> /// <param name="fileName">文件名。</param> /// <returns></returns> public static Encoding GetEncoding(string fileName){return GetEncoding(fileName, Encoding.Default);}/// <summary> /// 取得一个文本文件流的编码方式。 /// </summary> /// <param name="stream">文本文件流。</param> /// <returns></returns> public static Encoding GetEncoding(FileStream stream){return GetEncoding(stream, Encoding.Default);}/// <summary> /// 取得一个文本文件的编码方式。 /// </summary> /// <param name="fileName">文件名。</param> /// <param name="defaultEncoding">默认编码方式。当该方法无法从文件的头部取得有效的前导符时，将返回该编码方式。</param> /// <returns></returns> public static Encoding GetEncoding(string fileName, Encoding defaultEncoding){FileStream fs = new FileStream(fileName, FileMode.Open);Encoding targetEncoding = GetEncoding(fs, defaultEncoding);fs.Close();return targetEncoding;}/// <summary> /// 取得一个文本文件流的编码方式。 /// </summary> /// <param name="stream">文本文件流。</param> /// <param name="defaultEncoding">默认编码方式。当该方法无法从文件的头部取得有效的前导符时，将返回该编码方式。</param> /// <returns></returns> public static Encoding GetEncoding(FileStream stream, Encoding defaultEncoding){Encoding targetEncoding = defaultEncoding;if (stream != null && stream.Length >= 2){//保存文件流的前4个字节 byte byte1 = 0;byte byte2 = 0;byte byte3 = 0;byte byte4 = 0;//保存当前Seek位置 long origPos = stream.Seek(0, SeekOrigin.Begin);stream.Seek(0, SeekOrigin.Begin);int nByte = stream.ReadByte();byte1 = Convert.ToByte(nByte);byte2 = Convert.ToByte(stream.ReadByte());if (stream.Length >= 3){byte3 = Convert.ToByte(stream.ReadByte());}if (stream.Length >= 4){byte4 = Convert.ToByte(stream.ReadByte());}//根据文件流的前4个字节判断Encoding //Unicode {0xFF, 0xFE}; //BE-Unicode {0xFE, 0xFF}; //UTF8 = {0xEF, 0xBB, 0xBF}; if (byte1 == 0xFE && byte2 == 0xFF)//UnicodeBe {targetEncoding = Encoding.BigEndianUnicode;}if (byte1 == 0xFF && byte2 == 0xFE && byte3 != 0xFF)//Unicode {targetEncoding = Encoding.Unicode;}if (byte1 == 0xEF && byte2 == 0xBB && byte3 == 0xBF)//UTF8 {targetEncoding = Encoding.UTF8;}//恢复Seek位置 stream.Seek(origPos, SeekOrigin.Begin);}return targetEncoding;}// 新增加一个方法，解决了不带BOM的 UTF8 编码问题 /// <summary> /// 通过给定的文件流，判断文件的编码类型 /// </summary> /// <param name="fs">文件流</param> /// <returns>文件的编码类型</returns> public static System.Text.Encoding GetEncoding(Stream fs){byte[] Unicode = new byte[] { 0xFF, 0xFE, 0x41 };byte[] UnicodeBIG = new byte[] { 0xFE, 0xFF, 0x00 };byte[] UTF8 = new byte[] { 0xEF, 0xBB, 0xBF }; //带BOM Encoding reVal = Encoding.Default;BinaryReader r = new BinaryReader(fs, System.Text.Encoding.Default);byte[] ss = r.ReadBytes(4);if (ss[0] == 0xFE && ss[1] == 0xFF && ss[2] == 0x00){reVal = Encoding.BigEndianUnicode;}else if (ss[0] == 0xFF && ss[1] == 0xFE && ss[2] == 0x41){reVal = Encoding.Unicode;}else{if (ss[0] == 0xEF && ss[1] == 0xBB && ss[2] == 0xBF){reVal = Encoding.UTF8;}else{int i;int.TryParse(fs.Length.ToString(), out i);ss = r.ReadBytes(i);if (IsUTF8Bytes(ss))reVal = Encoding.UTF8;}}r.Close();return reVal;}/// <summary> /// 判断是否是不带 BOM 的 UTF8 格式 /// </summary> /// <param name="data"></param> /// <returns></returns> private static bool IsUTF8Bytes(byte[] data){int charByteCounter = 1;　 //计算当前正分析的字符应还有的字节数 byte curByte; //当前分析的字节. for (int i = 0; i < data.Length; i++){curByte = data[i];if (charByteCounter == 1){if (curByte >= 0x80){//判断当前 while (((curByte <<= 1) & 0x80) != 0){charByteCounter++;}//标记位首位若为非0 则至少以2个1开始如:110XXXXX...........1111110X　 if (charByteCounter == 1 || charByteCounter > 6){return false;}}}else{//若是UTF-8 此时第一位必须为1 if ((curByte & 0xC0) != 0x80){return false;}charByteCounter--;}}if (charByteCounter > 1){throw new Exception("非预期的byte格式!");}return true;}}