c# 判断Txt文件的编码格式

时间：2021-06-30 17:31:08 收藏：0 阅读：0
/// <summary>
 /// 获取文件的编码格式
 /// </summary>
 public class EncodingType
 {
     /// <summary>
     /// 给定文件的路径，读取文件的二进制数据，判断文件的编码类型
     /// </summary>
     /// <param name=“FILE_NAME“>文件路径</param>
     /// <returns>文件的编码类型</returns>
     public static System.Text.Encoding GetType(string FILE_NAME)
     {
         FileStream fs = new FileStream(FILE_NAME, FileMode.Open, FileAccess.Read);
         Encoding r = GetType(fs);
         fs.Close();
         return r;
     }
 
     /// <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 GetType(FileStream 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);
         int i;
         int.TryParse(fs.Length.ToString(), out i);
         byte[] ss = r.ReadBytes(i);
         if (IsUTF8Bytes(ss) || (ss[0] == 0xEF && ss[1] == 0xBB && ss[2] == 0xBF))
         {
             reVal = Encoding.UTF8;
         }
         else 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;
         }
         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;
     }
 
 }
 
转自：https://www.cnblogs.com/cyberarmy/p/5652835.html