private void btnSave_Click(object sender, EventArgs e)
        {
            if (rTxt.Text.Trim() != "")
            {
                SaveToTxtFile();
            }
            else
            {
                MessageBox.Show("请选择需要保持的txt文件！");
            }
        }

        /// <summary>
        /// 保存文件
        /// </summary>
        private void SaveToTxtFile()
        {
            try
            {
                 * 例如：new StreamWriter(fs, true, Encoding.GetEncoding("GB2312"));是错误的*/
                StreamWriter m_streamWriter = new StreamWriter(txtPath.Text, false, Encoding.GetEncoding("GB2312"));    //要保存文本文件的位置

                m_streamWriter.Flush();

                // 使用StreamWriter来往文件中写入内容

                m_streamWriter.BaseStream.Seek(0, SeekOrigin.Begin);

                // 把richTextBox1中的内容写入文件

                m_streamWriter.Write(rTxt.Text);   //将需要保存的内容写入到文件中

                //关闭此文件

                m_streamWriter.Flush();

                m_streamWriter.Close();

                MessageBox.Show("保存成功！");
            }
            catch (Exception ex)
            {
                MessageBox.Show("保存错误！请重试！错误信息：" + ex.Message); return;
            }
        }