窗体生命周期

参考链接：https://www.cnblogs.com/animal/articles/3506113.html

在整个窗体生命周期中，有以下6个重要的事件：

1.Load：窗体加载时触发，主要用于加载初始数据

2.Shown：窗体显示时触发

3.Activated：窗体获取焦点时触发

4.Deactivate：窗体失去焦点时触发

5.FormClosing：窗体关闭过程中触发

6.FormClosed：窗体关闭完成触发

我们打开上一章的解决方案，在MainForm.cs里面键入如下代码：

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace WinFrom
{
	public class MainForm : Form//继承Form
	{
		private int index = 0;//判断执行顺序
		private string msg = string.Empty;//用于记录事件触发顺序
		public MainForm()
		{
			#region 加载事件
			this.Activated += new System.EventHandler(this.MainForm_Activated);
			this.Deactivate += new System.EventHandler(this.MainForm_Deactivate);
			this.FormClosing += new System.Windows.Forms.FormClosingEventHandler(this.MainForm_FormClosing);
			this.FormClosed += new System.Windows.Forms.FormClosedEventHandler(this.MainForm_FormClosed);
			this.Load += new System.EventHandler(this.MainForm_Load);
			this.Shown += new System.EventHandler(this.MainForm_Shown);
			#endregion

		}

		/// <summary>
		/// 窗体加载时事件，主要用于加载初始化数据
		/// </summary>
		/// <param name="sender"></param>
		/// <param name="e"></param>
		private void MainForm_Load(object sender, EventArgs e)
		{
			msg = msg + "Load事件，执行顺序" + (++index) + "\r\n";
		}
		/// <summary>
		/// 窗体显示时事件
		/// </summary>
		/// <param name="sender"></param>
		/// <param name="e"></param>
		private void MainForm_Shown(object sender, EventArgs e)
		{
			msg = msg + "Shown事件，执行顺序" + (++index) + "\r\n";
		}
		/// <summary>
		/// 窗体获得焦点事件
		/// </summary>
		/// <param name="sender"></param>
		/// <param name="e"></param>
		private void MainForm_Activated(object sender, EventArgs e)
		{
			msg = msg + "Activated事件，执行顺序" + (++index) + "\r\n";
		}
		/// <summary>
		/// 窗体失去焦点事件
		/// </summary>
		/// <param name="sender"></param>
		/// <param name="e"></param>
		private void MainForm_Deactivate(object sender, EventArgs e)
		{
			msg = msg + "Deactivate事件，执行顺序" + (++index) + "\r\n";

		}
		/// <summary>
		/// 窗体关闭完成事件
		/// </summary>
		/// <param name="sender"></param>
		/// <param name="e"></param>
		private void MainForm_FormClosed(object sender, FormClosedEventArgs e)
		{
			msg = msg + "Closed事件，执行顺序" + (++index) + "\r\n";
			File.WriteAllText(@"d:\1.txt", msg);
		}
		/// <summary>
		/// 窗体关闭进行中事件
		/// </summary>
		/// <param name="sender"></param>
		/// <param name="e"></param>
		private void MainForm_FormClosing(object sender, FormClosingEventArgs e)
		{
			msg = msg + "Closing事件，执行顺序" + (++index) + "\r\n";
		}
	}
}

执行，单击桌面，在单击窗体，实现窗体的“失去/获得”焦点的过程，打开D:\1.txt