主动依据文本文件的字符集编码加载文件内容字符串，并反对按原始编码格局再次写入。
using System;using System.IO;using System.Linq;using System.Text;/// <summary> /// 获取文件的编码格局 /// </summary> public class TextEncode{ public Encoding Encoding { get; private set; } public byte[] BOM { get; private set; } public string ReadText(string fileName, out Encoding enc) { var r = ReadText(fileName); enc = Encoding; return r; } public string ReadText(string fileName) { Encoding encoding = null; byte[] bytes = File.ReadAllBytes(fileName); int bomLen = 0; if (bytes.Length > 1) { if (bytes[0] == 0xFE && bytes[1] == 0xFF) //UTF-16（大端序） { encoding = new UnicodeEncoding(true, true); bomLen = 2; } else if (bytes[0] == 0xFF && bytes[1] == 0xFE) //UTF-16（小端序） { encoding = new UnicodeEncoding(false, true); bomLen = 2; } } if (encoding == null && bytes.Length > 2) { if ((bytes[0] == 0xEF && bytes[1] == 0xBB && bytes[2] == 0xBF)) //UTF-8 { encoding = new UTF8Encoding(true); bomLen = 3; } } if (encoding == null && bytes.Length > 3) { if (bytes[0] == 0x00 && bytes[1] == 0x00 && bytes[2] == 0xFE && bytes[3] == 0xFF) //UTF-32（大端序） { encoding = new UTF32Encoding(true, true); bomLen = 4; } else if (bytes[0] == 0xFF && bytes[1] == 0xFE && bytes[2] == 0x00 && bytes[3] == 0x00) //UTF-32（小端序） { encoding = new UTF32Encoding(false, true); bomLen = 4; } } if (encoding == null && IsUTF8Bytes(bytes)) { encoding = Encoding.UTF8; //UTF8无BOM } if (encoding == null) encoding = Encoding.Default; Encoding = encoding; BOM = new byte[bomLen]; Array.Copy(bytes, BOM, bomLen); return encoding.GetString(bytes, bomLen, bytes.Length - bomLen); } /// <summary> /// 判断是否是不带 BOM 的 UTF8 格局 /// </summary> /// <param name="data"></param> /// <returns></returns> private bool IsUTF8Bytes(byte[] data) { int charByteCounter = 1; //计算以后正剖析的字符应还有的字节数 byte curByte; //以后剖析的字节. for (int i = 0; i < data.Length; i++) { curByte = data[i]; if (curByte == 0) throw new FormatException("非预期的byte格局"); if (charByteCounter == 1) { if (curByte >= 0x80) { //判断以后 while (((curByte <<= 1) & 0x80) != 0) { charByteCounter++; } //标记位首位若为非0 则至多以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 FormatException("非预期的byte格局"); } return true; } /// <summary> /// 已雷同的Encoding和BOM再次写入 /// </summary> public void WriteBySameEncoding(string fileName, string content) { if (BOM == null) { throw new Exception("须要先调用ReadText办法"); } using (var file = File.Create(fileName)) { file.Write(BOM, 0, BOM.Length); var bytes = Encoding.GetBytes(content); file.Write(bytes, 0, bytes.Length); } }}