Stream myStream = null;

            OpenFileDialog openFileDialog1 = new OpenFileDialog();

            openFileDialog1.InitialDirectory = "d:\\";

            openFileDialog1.Filter = "ext files (*.txt)|*.txt|All files(*.*)|*>**";

            openFileDialog1.FilterIndex = 2;

            openFileDialog1.RestoreDirectory = true;

            if (openFileDialog1.ShowDialog() == DialogResult.OK)

            {

                try

                {

                    if ((myStream = openFileDialog1.OpenFile()) != null)

                    {

                        StreamReader st = new StreamReader(openFileDialog1.FileName, Encoding.GetEncoding("gb2312"));

                        string str = st.ReadLine();

                        while (str != null)

                        {

                            richTextBox1.AppendText(str);

                            richTextBox1.AppendText("\n");

                            str = st.ReadLine();

                        }

                    }

                }catch(Exception ex){

                    MessageBox.Show("打开文件出错："+ex.Message);

                }

SaveFileDialog saveFileDialog1 = new SaveFileDialog();

            saveFileDialog1.InitialDirectory = "d:\\";

            saveFileDialog1.Filter = "ext files (*.txt)|*.txt|All files(*.*)|*>**";

            saveFileDialog1.FilterIndex = 2;

            saveFileDialog1.RestoreDirectory = true;

            DialogResult dr = saveFileDialog1.ShowDialog();

            if (dr == DialogResult.OK && saveFileDialog1.FileName.Length > 0)

            {

                richTextBox1.SaveFile(saveFileDialog1.FileName,RichTextBoxStreamType.PlainText);

                MessageBox.Show("存储文件成功！","保存文件");

            }

 ColorDialog colorDialog1 = new ColorDialog();

            colorDialog1.AllowFullOpen = false;

            colorDialog1.Color = richTextBox1.ForeColor;

            colorDialog1.ShowHelp = true;

            if(colorDialog1.ShowDialog()==DialogResult.OK)

            {

                richTextBox1.ForeColor = colorDialog1.Color;

             }

FontDialog fontDialog = new FontDialog();

            fontDialog.Font = richTextBox1.Font;

            fontDialog.Color = richTextBox1.ForeColor;

            if (fontDialog.ShowDialog() != DialogResult.Cancel)

            {

                richTextBox1.Font = fontDialog.Font;

                richTextBox1.ForeColor = fontDialog.Color;

            }