一个超级简单的文件流操作WINDOW应用程序

一直都没写过windows应用程序，今天写了几个操作文件的，非常简单：

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

namespace WindowsApplication1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
                this.openFileDialog1.ShowDialog();

                this.textBox1.Text = this.openFileDialog1.FileName;
        }

        private void button2_Click(object sender, EventArgs e)
        {
            this.folderBrowserDialog1.SelectedPath = Application.StartupPath;
            this.folderBrowserDialog1.ShowDialog();
            this.textBox2.Text = this.folderBrowserDialog1.SelectedPath;
        }

        private void button3_Click(object sender, EventArgs e)
        {
            if(this.textBox2.Text.Trim()!="")
            {
                System.Diagnostics.Process.Start(this.textBox2.Text);
            }

        }

        private void button4_Click(object sender, EventArgs e)
        {
            string _fileName = "\\shine.txt";
            string _text = this.textBox3.Text;
            _fileName = this.textBox2.Text+_fileName;
            System.IO.StreamWriter sw = new System.IO.StreamWriter(_fileName);
            sw.Write(_text);
            sw.Close();
            this.Close();



        }
    }
}