读取英文和数字是没问题的，
一但有了中文就出现乱码，怎么解决？
关键代码：
try
            {
                FileStream fs = File.OpenRead(this.txtFilename.Text);
                if(File.Exists(this.txtFilename.Text))
                {
                    byte[] arr = new byte[1024];
                    UTF8Encoding data = new UTF8Encoding(true);
                    while(fs.Read(arr,0,arr.Length) > 0)
                    {
                        this.txtContent.Text = data.GetString(arr);
                    }
                }
                else
                {
                    MessageBox.Show("文件不存在");
                }
            }
            catch(Exception ex)
            {
                MessageBox.Show(ex.Message);
            }