【C#】获取文件编码格式 与 转换成UTF-8-BOM编码

1，获取文件编码格式

        private static Encoding getEncoding( string filePath)
        {

            using (var reader = new StreamReader(filePath, Encoding.Default, true))
            {
                if (reader.Peek() >= 0) // you need this!
                    reader.Read();

                Encoding encoding = reader.CurrentEncoding;
                reader.Close();
                return encoding;
            }
        }

2，转换成UTF-8-BOM编码格式

（实测结果是，对日文转换编码格式后会乱码，德文则正常，有待继续研究）

        public static void changeFileEncodingToUTF8BOM(string filePath)
        {
            //用到了上面的函数getEncoding()
            Encoding oldEndcoding = getEncoding(filePath);


            //读取文件内容
            string str = string.Empty;
            using (StreamReader sr = new StreamReader(filePath, oldEndcoding))
            {
                str = sr.ReadToEnd();
                sr.Close();
            }
            //以UTF-8带BOM格式重新写入文件
            Encoding newEncoding = new UTF8Encoding(true);
            using (StreamWriter sw = new StreamWriter(filePath, false, newEncoding ))
            {
                sw.Write(str);
                sw.Close();
            }        
        }