C#获取文本文件的编码，自动区分GB2312和UTF8

C# 获取文本文件的编码，自动区分GB2312和UTF8

以下是获取文件编码的一个类

using System; 

using System.IO; 

using System.Text; 



/// <summary> 

/// FileEncoding 的摘要说明 

/// </summary> 

namespace FileEncoding 

{ 

/// <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; 

} 



} 





} 

以下是使用示例

#region 打开按钮 

/// <summary> 

/// 打开按钮 

/// </summary> 

/// <param name=“sender“></param> 

/// <param name=“e“></param> 

private void txtMenuOpen_Click(object sender, EventArgs e) 

{ 

string fName; 

OpenFileDialog openFileDialog = new OpenFileDialog(); 

openFileDialog.InitialDirectory = "";//注意这里写路径时要用c:而不是c: 

openFileDialog.Filter = "文本文档|*.txt"; 

openFileDialog.RestoreDirectory = true; 

openFileDialog.FilterIndex = 1; 

if (openFileDialog.ShowDialog() == DialogResult.OK) 

{ 

fName = openFileDialog.FileName; 



txtBox.Text = System.IO.File.ReadAllText(fName, 

FileEncoding.EncodingType.GetType(fName)); 

} 



} 

#endregion