如何解决文本文件编码问题？在读取文件时不知道要读取的文件是什么编码，怎么获得？

Question

最近做一个文件批量处理的工具。但是碰到这样一个问题，比如有些源码文件是utf-8编码格式，假设我不知道这些编码。我就会以gb2312编码方式读取文件，那样会出乱码？？怎么获取这个文件的编码类型

Answer 1

通过前几个字节判断文本的编码格式，参考如下代码：
public string LoadTextFile(string filename)
{
    if (!File.Exists(filename)) return string.Empty;
    FileStream fs = new FileStream(filename, FileMode.Open, FileAccess.Read);
    try
    {
        byte[] buffer = new byte[3];
        int l = fs.Read(buffer, 0, buffer.Length);
        if (l >= 2 && buffer[0] == 0xff && buffer[1] == 0xfe) // unicode
        {
            buffer = new byte[fs.Length - 2];
            fs.Seek(2, SeekOrigin.Begin);
            fs.Read(buffer, 0, buffer.Length);
            return Encoding.Unicode.GetString(buffer);
        }        if (l >= 2 && buffer[0] == 0xfe && buffer[1] == 0xff) // unicodeFFFE
        {
            buffer = new byte[fs.Length - 2];
            fs.Seek(2, SeekOrigin.Begin);
            fs.Read(buffer, 0, buffer.Length);
            return Encoding.GetEncoding("unicodeFFFE").GetString(buffer);
        }        if (l >= 3 && buffer[0] == 0xef && buffer[1] == 0xbb && buffer[2] == 0xbf) // utf8
        {
            buffer = new byte[fs.Length - 3];
            fs.Seek(3, SeekOrigin.Begin);
            fs.Read(buffer, 0, buffer.Length);
            return Encoding.UTF8.GetString(buffer);
        }        // default
        fs.Seek(0, SeekOrigin.Begin);
        buffer = new byte[fs.Length];
        fs.Read(buffer, 0, buffer.Length);
        return Encoding.Default.GetString(buffer);
    }
    finally
    {
        fs.Close();
    }
}private void button1_Click(object sender, EventArgs e)
{
    Console.WriteLine(LoadTextFile(@"c:\temp\tempa.txt"));
    Console.WriteLine(LoadTextFile(@"c:\temp\tempb.txt"));
    Console.WriteLine(LoadTextFile(@"c:\temp\tempc.txt"));
    Console.WriteLine(LoadTextFile(@"c:\temp\tempd.txt"));
}

Answer 2

还是不行，，，如果是一个utf-8的php文件读出来成乱码

Answer 3

/// <summary>
 2        /// 获得文件编码
 3        /// </summary>
 4        /// <param name="content">文件流的字节数组</param>
 5        /// <returns>字符编码</returns>
 6        public static Encoding GetFileEncoding(byte[] content)
 7        {
 8            if (content.Length > 0)
 9            {
10                switch (content[0])
11                {
12                    case 104:
13                        return Encoding.Default;
14                    case 255:
15                        return Encoding.Unicode;
16                    case 254:
17                        return Encoding.BigEndianUnicode;
18                    case 239:
19                        return Encoding.UTF8;
20                    default:
21                        return Encoding.Default;
22                }
23            }
24            return Encoding.Default;
25        }<summary>
        /// 读文件流
        /// </summary>
        /// <param name="stream">文件流;如:File.OpenRead(fileCurrentPath)</param>
        /// <param name="encoding">字符编码;如:Encoding.UTF8</param>
        /// <returns>流字符串</returns>
        public static string ReadFromStream(FileStream stream, Encoding encoding)
        {
            byte[] content = new byte[stream.Length];
            stream.Read(content, 0, content.Length);
            stream.Close();
            stream = null;
            if (encoding == Encoding.Default)
            {
                encoding = GetFileEncoding(content);
            }
            return encoding.GetString(content);
        }
       
        public static string ReadFromStream(FileStream stream,out Encoding encoding)
        {
            byte[] content = new byte[stream.Length];
            stream.Read(content, 0, content.Length);
            stream.Close();
            stream = null;
            encoding = GetFileEncoding(content);
            return encoding.GetString(content);
        } 1   /**//// <summary>
 2        /// 写文件流
 3        /// </summary>
 4        /// <param name="stream">文件流;如:File.OpenWrite(fileCurrentPath)</param>
 5        /// <param name="encoding">字符编码;如:Encoding.UTF8</param>
 6        /// <param name="Text">要写的字符串</param>
 7        /// <returns>bool</returns>
 8        public static bool WriteToStream(FileStream stream, Encoding encoding, string Text)
 9        {
10            try
11            {
12
13                byte[] content = encoding.GetBytes(Text.Replace("\n", "\r\n"));
14                stream.SetLength(content.Length);
15                stream.Write(content, 0, content.Length);
16                stream.Close();
17                return true;
18            }
19            catch
20            {
21                return false;
22            }
23        }