读写文件示例代码

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;

namespace study
{
    public partial class Form3 : Form
    {
        public Form3()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            String editingFileName = "";
            Boolean saveAllowed = true;

            // Displays the OpenFileDialog.
            if (openFileDialog1.ShowDialog() == DialogResult.OK)
            {
                // Opens the file stream for the file selected by the user.
                using (System.IO.Stream userStream = openFileDialog1.OpenFile())
                {
                    this.RtfBoxMain.LoadFile(userStream,
                        RichTextBoxStreamType.PlainText);
                    userStream.Close();
                }

                // Tries to get the file name selected by the user.
                // Failure means that the application does not have
                // unrestricted permission to the file.
                try
                {
                    editingFileName = openFileDialog1.FileName;
                }
                catch (Exception ex)
                {
                    if (ex is System.Security.SecurityException)
                    {
                        // The application does not have unrestricted permission 
                        // to the file so the save feature will be disabled.
                        saveAllowed = false;
                    }
                    else
                    {
                        throw ex;
                    }
                }
            }

        }

        private void button2_Click(object sender, EventArgs e)
        {
            String editingFileName = "";
            Boolean saveAllowed = true;

            // Displays the OpenFileDialog.
            if (saveFileDialog1.ShowDialog() == DialogResult.OK)
            {
                // Opens the file stream for the file selected by the user.
                using (System.IO.Stream userStream = saveFileDialog1.OpenFile())
                {
                    this.RtfBoxMain.SaveFile(userStream,
                        RichTextBoxStreamType.PlainText);
                    userStream.Close();
                }
            }
        }
    }
}