自动感知窗体的关闭事件

有些时候当程序退出时，可能需要做一些善后处理工作。.Net框架为我们提供了非常丰富及方便的窗体关闭检测手段，我们只要捕获这些相关事件，然后对应处理即可，从而达到不同原因关闭窗体采取不同操作的目的。
首先，创建一个默认的Window Form. Application，我们需要重载Form基类的OnClosing事件，然后获取窗体关闭事件的参数信息，即FormClosingEventArgs类的实例，根据关闭窗体的不同原因，即FormClosingEventArgs类的CloseReason属性，提示用户作出相应处理。Form1.cs的全部源码如下：
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.DataL;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
namespace WindowsFormsApplication1
{
 public partial class Form1 : Form
{
      public Form1()
{
 InitializeComponent();
}
public static bool ShowMessage(string s)
{
DialogResult result = MessageBox.Show(s + "\n\n确定要关闭窗体吗？", "提示", MessageBoxButtons.YesNo, MessageBoxIcon.Question);
return result == DialogResult.No;
}

protected override void OnClosing(CancelEventArgs e)
{
FormClosingEventArgs fce = e as FormClosingEventArgs;
 if (fce != null)
{
                switch (fce.CloseReason)
                {      case CloseReason.ApplicationExitCall:ITPUB个人空间a u9v3V9}'OwF
                        e.Cancel = Form1.ShowMessage("程序正准备退出！");
                        break;
                        case CloseReason.FormOwnerClosing:
                        e.Cancel = Form1.ShowMessage("主窗体正在关闭！");
                        break;
                        case CloseReason.MdiFormClosing:
                        e.Cancel = Form1.ShowMessage("MDI主窗体正在试图关闭！");
                        break;
                        case CloseReason.None:
                        e.Cancel = Form1.ShowMessage("正在关闭窗体，但原因未知！");
                        break;
                        case CloseReason.TaskManagerClosing:ITPUB个人空间 R WJO E
                        e.Cancel = Form1.ShowMessage("任务管理器正在试图关闭窗体并终止程序！");
                        break;
                        case CloseReason.UserClosing:
                       e.Cancel = Form1.ShowMessage("用户正在试图关闭窗体！");
                        break;
                       case CloseReason.WindowsShutDown:
                        e.Cancel = Form1.ShowMessage("Windows 正在关闭，并尝试关闭窗体！");
                        break;
                }
   }
            base.OnClosing(e);ITPUB个人空间?1\6m;wEp
               }
           }
       }
   }
}
在事件结尾不要忘记添加对基类的OnClosing()的调用，以保证类的完整性！