//使用 OpenFile 從篩選的選擇中打開(kāi)文件
using System.Diagnostics;
using System.Security;
 
namespace WinFormsApp1
{
    public partial class OpenFileDialogForm : Form
    {
        private readonly Button selectButton;
        private readonly OpenFileDialog openFileDialog1;
 
        public OpenFileDialogForm()
        {
            InitializeComponent();
 
            //新建openFileDialog控件
            openFileDialog1 = new OpenFileDialog()
            {
                FileName = "Select a text file",      //OpenFileDialog窗體提示
                Filter = "Text files (*.txt)|*.txt",  //選擇什么擴(kuò)展名類型的文件
                Title = "Open text file"              //OpenFileDialog窗體的抬頭
            };
 
            //新建按鈕及點(diǎn)擊事件
            selectButton = new Button()
            {
                Size = new Size(100, 20),
                Location = new Point(15, 15),
                Text = "Select file"
            };
            selectButton.Click += new EventHandler(SelectButton_Click);
            Controls.Add(selectButton);
        }
 
        /// <summary>
        /// 按鈕點(diǎn)擊事件應(yīng)用
        /// 使用 Button 控件的 Click 事件處理程序打開(kāi)包含僅顯示文本文件的篩選器的 OpenFileDialog。 
        /// 用戶選擇文本文件并選擇“確定”后，可用 OpenFile 方法在記事本中打開(kāi)該文件
        /// </summary>
        private void SelectButton_Click(object? sender, EventArgs e)
        {
            if (openFileDialog1.ShowDialog() == DialogResult.OK)
            {
                try
                {
                    var filePath = openFileDialog1.FileName;
                    using Stream str = openFileDialog1.OpenFile();
                    Process.Start("notepad.exe", filePath);
                }
                catch (SecurityException ex)
                {
                    MessageBox.Show($"Security error.\n\nError message: {ex.Message}\n\n" +
                    $"Details:\n\n{ex.StackTrace}");
                }
            }
        }
    }
}

//使用 StreamReader 以流的形式讀取文件
using System.Security;
namespace _05_3
{
    public partial class Form1 : Form
    {
        private readonly Button selectButton;
        private readonly OpenFileDialog openFileDialog1;
        private readonly TextBox textBox1;
 
        public Form1()
        {
            InitializeComponent();
 
            //創(chuàng)建OpenFileDialog控件openFileDialog1
            openFileDialog1 = new OpenFileDialog();
 
            //創(chuàng)建按鈕控件selectButton及添加點(diǎn)擊事件
            selectButton = new Button
            {
                Size = new Size(100, 20),
                Location = new Point(15, 15),
                Text = "Select file"
            };
            selectButton.Click += new EventHandler(SelectButton_Click);
 
            //創(chuàng)建文本框控件textBox1
            textBox1 = new TextBox
            {
                Size = new Size(300, 300),
                Location = new Point(15, 40),
                Multiline = true,
                ScrollBars = ScrollBars.Vertical
            };
 
            //設(shè)置Form1表格大小
            ClientSize = new Size(330, 360);
 
            Controls.Add(selectButton);
            Controls.Add(textBox1);
        }
 
        //自定義方法
        private void SetText(string text)
        {
            textBox1.Text = text;
        }
 
        /// <summary>
        /// 使用 StreamReader 以流的形式讀取文件
        /// 使用 Windows 窗體 Button 控件的 Click 事件處理程序通過(guò) ShowDialog 方法打開(kāi) OpenFileDialog。
        /// 用戶選擇一個(gè)文件并選擇“確定”后，StreamReader 類的實(shí)例將讀取該文件，并在窗體的文本框中顯示文件內(nèi)容。
        /// </summary>
        private void SelectButton_Click(object? sender, EventArgs e)
        {
            if (openFileDialog1.ShowDialog() == DialogResult.OK)
            {
                try
                {
                    var sr = new StreamReader(openFileDialog1.FileName);
                    SetText(sr.ReadToEnd());
                }
                catch (SecurityException ex)
                {
                    MessageBox.Show($"Security error.\n\nError message: {ex.Message}\n\n" +
                    $"Details:\n\n{ex.StackTrace}");
                }
            }
        }
    }
}