C# -采用npoi对excel进行生僻字与繁体字查找

因工作需要对批量发工资业务进行加密，但加密码后有好多乱码，后分晰原因是加密程序只能“GB2312”编程的字符进行加密，其它的会产生乱码。需要把生僻字与繁体字找出来，现依excel 文件，找出里面不是"GB2312"的字符。代码见下面：

using System;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.IO;
using NPOI.XSSF.UserModel;
using NPOI.HSSF.UserModel;
using Microsoft.Win32;
using NPOI.SS.UserModel;
namespace 代发工资检查工具
{
    /// <summary>
    /// MainWindow.xaml 的交互逻辑
    /// </summary>
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
        }
        private void button1_Click(object sender, RoutedEventArgs e)
        {
            OpenFileDialog openFileDialog = new OpenFileDialog();
            openFileDialog.Filter = "excel文件(xls,xlsx)|*.xls;*.xlsx";
            openFileDialog.ShowDialog();
            textbox1.Text = openFileDialog.FileName;
            if (openFileDialog.FileName.Length == 0)
            {
                MessageBox.Show("请选择文件", "提示", MessageBoxButton.OK, MessageBoxImage.Error);
                return;
            }
            try
            {
                using (FileStream fileStream = new FileStream(openFileDialog.FileName, FileMode.Open, FileAccess.Read))
                {
                    ISheet sheet = null;
                    if (System.IO.Path.GetExtension(openFileDialog.FileName) == ".xls")
                    {
                        HSSFWorkbook workbook = new HSSFWorkbook(fileStream);
                        sheet = workbook.GetSheetAt(0);
                    }
                    else
                    {
                        MessageBox.Show("你的文件扩展名是.xlsx，正确因另存为.xls，但程序照样帮您检查生僻字");
                        XSSFWorkbook workbook = new XSSFWorkbook(fileStream);
                        sheet = workbook.GetSheetAt(0);
                    }
                    textbox2.Text = "正在检测中...";
                    for (int i = 0; i <= sheet.LastRowNum; i++)
                    {
                        var row = sheet.GetRow(i);
                        textbox2.AppendText($"
正在检查表格第{i + 1}行......表格共{sheet.LastRowNum + 1}行");
                        if (row != null)
                        {
                            for (int j = 0; j < row.LastCellNum; j++)
                            {
                                for (int k = 0; k <= row.GetCell(j).ToString().Length - 1; k++)
                                {
                                    // MessageBox.Show($"k的值是：{k}.它的当前值是：{row.GetCell(j)},它当前的长度是：{row.GetCell(j).ToString().Length},它的当前测试值是:{row.GetCell(j).ToString()[k].ToString()}");
                                    byte[] bytes = Encoding.GetEncoding("GB2312").GetBytes(row.GetCell(j).ToString()[k].ToString());
                                    if (bytes.Length <= 1)
                                    {
                                        byte byte1 = bytes[0];
                                        if (byte1 == 32)
                                        {
                                            MessageBox.Show($"
 第{i + 1}行的：{row.GetCell(j).ToString()[k]} 有空格会造成乱码的字符");
                                            textbox2.AppendText($"
 第{i + 1}行的：{row.GetCell(j).ToString()[k]} 有空格会造成乱码的字符");
                                        }
                                        continue;
                                    }
                                    else
                                    {
                                        byte byte1 = bytes[0];
                                        byte byte2 = bytes[1];
                                        if (byte1 >= 176 && byte1 <= 247 && byte2 >= 160 && byte2 <= 254)   //判断是否是GB2312编码
                                        {
                                            continue;
                                        }
                                        else
                                        {
                                            MessageBox.Show($"
 第{i + 1}行的：{row.GetCell(j).ToString()[k]} 是生僻字或繁体字或会造成乱码的字符");
                                            textbox2.AppendText($"
 第{i + 1}行的：{row.GetCell(j).ToString()[k]} 是生僻字或繁体字或会造成乱码的字符");
                                        }
                                    }
                                }
                            }
                        }
                    }
                }
                textbox2.AppendText("
检测完成...");
            }
            catch (Exception)
            {
                // MessageBox.Show("excel表格数据有误，请检查excel表格再试" + "

" + ea);
                MessageBox.Show("excel表格数据有误，是否只改了文件扩展名，正确因打开文件，另存为*.xls");
                return;
            }
        }
    }
}