c# - 当前上下文中不存在名称“WM_DEVICECHANGE”

Question

我正在尝试检测 USB 到达事件。我试图覆盖wndproc()以获取我的消息。但我正面临 Windows 消息的错误。

错误是：

The name 'WM_DEVICECHANGE' does not exist in the current context

The name 'DBT_DEVICEARRIVAL' does not exist in the current context

这也是我尝试过的代码。

using System;
using System.Collections.Generic;
using System.Text;
using System.Windows.Forms;         
using System.IO;
using Microsoft.Win32.SafeHandles; 

namespace USBCheckerApp
{
    public partial class Form1 : Form
    {
        bool bDeviceFound = false;

        public Form1()
        {
            InitializeComponent();

        }

        private void Form1_Load(object sender, EventArgs e)
        {
            if (!bDeviceFound)
            {
                button1.Enabled = false;
            }


        }
        [System.Security.Permissions.PermissionSet(System.Security.Permissions.SecurityAction.Demand, Name = "FullTrust")]
        protected override void WndProc(ref Message m)
        {
            switch (m.Msg)
            {
                case WM_DEVICECHANGE:
                    if (m.WParam == DBT_DEVICEARRIVAL)
                    {
                        MessageBox.Show("MEDIA FOUND");
                    }
            }

        }

    }
}

添加以便您可以建议任何更新。谢谢

Answer 1

您必须声明和定义常量的值：

private const int DBT_DEVICEARRIVAL = 0x8000;
private const int WM_DEVICECHANGE = 0x0219;