private void button1_Click(object sender, System.EventArgs e)
  {
   openFileDialog1.Filter ="所有文件*.*|*.*|文本文件*.txt|*.txt";
   openFileDialog1.FilterIndex =2;
   if(openFileDialog1.ShowDialog ()==DialogResult.OK )
   {
    FileStream fr=new FileStream(openFileDialog1.FileName ,FileMode.OpenOrCreate ,FileAccess.Read);
    byte []  filebtye=new byte[fr.Length ];
    fr.Read(filebtye,0,Convert.ToInt32 (fr.Length) );
    char [] filechar=new char [fr.Length ];
    Encoding myencode=Encoding.GetEncoding (932);
    myencode.GetChars (filebtye,0,Convert.ToInt32 (fr.Length) ,filechar,0);
    string s= new string (filechar);
    fr.Close ();
    richTextBox1.Text =s;
   }
  }

  private void button2_Click(object sender, System.EventArgs e)
  {
   saveFileDialog1.Filter ="所有文件*.*|*.*|文本文件*.txt|*.txt";
   saveFileDialog1.FilterIndex =2;
   if(saveFileDialog1.ShowDialog ()==DialogResult.OK )
   {
    FileStream fs=new FileStream (saveFileDialog1.FileName ,FileMode.OpenOrCreate,FileAccess.Write );
    Encoding wencode=Encoding.GetEncoding(932);
    byte [] filewrite=wencode.GetBytes (richTextBox1.Text );
    fs.Write(filewrite,0,filewrite.Length );
    fs.Close ();
   }
  }