在.NET中探测U盘的插入/拔出-蒲公英云

在.NET中探测U盘的插入/拔出

快来打我* 2022-09-28 14:29 254阅读 0赞

有同学向我问这个问题，于是就Google了一下找到答案，不过是C下的，我将其改编成了C#的。
　　当设备被插入/拔出的时候，WINDOWS会向每个窗体发送WM_DEVICECHANGE 消息，当消息的wParam 值等于 DBT_DEVICEARRIVAL 时，表示Media设备被插入并且已经可用；如果wParam值等于DBT_DEVICEREMOVECOMPLETE，表示Media设备已经被移出。

它们的lParam都指向一个 DEV_BROADCAST_HDR结构体，其原形如下：

1 typedef struct _DEV_BROADCAST_HDR
2 {
3 DWORD dbch_size;
4 DWORD dbch_devicetype;
5 DWORD dbch_reserved;
6 } DEV_BROADCAST_HDR, *PDEV_BROADCAST_HDR;
这个结构体仅仅是一个“头”（HDR），其后还有附加数据，dbch_size表示结构体实例的字节数，当其中的dbch_devicetype字段值等于DBT_DEVTYP_VOLUME时，表示当前设备是逻辑驱动器，且lParam实际上指向的应该是DEV_BROADCAST_VOLUME 结构体实例（真佩服这种逻辑），DEV_BROADCAST_VOLUME 结构体原形如下：

1 typedef struct _DEV_BROADCAST_VOLUME {
2 DWORD dbcv_size;
3 DWORD dbcv_devicetype;
4 DWORD dbcv_reserved;
5 DWORD dbcv_unitmask;
6 WORD dbcv_flags;
7 } DEV_BROADCAST_VOLUME, *PDEV_BROADCAST_VOLUME;其中dbcv_unitmask 字段表示当前改变的驱动器掩码，第一位表示驱动器号A，第二位表示驱动器号B，第三位表示驱动器号C，以此类推…… dbcv_flags 表示驱动器的类别，如果等于1，则是光盘驱动器；如果是2，则是网络驱动器；如果是硬盘、U盘则都等于0

　　所以，我只需要在程序中捕捉WM_DEVICECHANGE 消息，然后根据具体情况去处理即可，下面是我的测试代码：

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

namespace UDiskDetect
{
public partial class Form1 : Form
{
public Form1()

InitializeComponent();

}

private void Form1_Load(object sender, EventArgs e)
{

}

[StructLayout(LayoutKind.Sequential)]
struct DEV_BROADCAST_HDR
{
public UInt32 dbch_size;
public UInt32 dbch_devicetype;
public UInt32 dbch_reserved;
}

[StructLayout(LayoutKind.Sequential)]
struct DEV_BROADCAST_VOLUME
{
public UInt32 dbcv_size;
public UInt32 dbcv_devicetype;
public UInt32 dbcv_reserved;
public UInt32 dbcv_unitmask;
public UInt16 dbcv_flags;
}
protected override void DefWndProc(ref Message m)
{
if (m.Msg == 0x0219)//WM_DEVICECHANGE
{
switch (m.WParam.ToInt32())
{
case 0x8000://DBT_DEVICEARRIVAL
{
DEV_BROADCAST_HDR dbhdr = (DEV_BROADCAST_HDR)Marshal.PtrToStructure(m.LParam, typeof(DEV_BROADCAST_HDR));

if (dbhdr.dbch_devicetype == “COLOR: #000000”> 0x00000002)//DBT_DEVTYP_VOLUME
{
DEV_BROADCAST_VOLUME dbv = (DEV_BROADCAST_VOLUME)Marshal.PtrToStructure(m.LParam, typeof(DEV_BROADCAST_VOLUME));
if (dbv.dbcv_flags == 0)
AddVolumes(GetVolumes(dbv.dbcv_unitmask));
}
break;
}
case 0x8004://DBT_DEVICEREMOVECOMPLETE
{
DEV_BROADCAST_HDR dbhdr = (DEV_BROADCAST_HDR)Marshal.PtrToStructure(m.LParam, typeof(DEV_BROADCAST_HDR));

                        if (dbhdr.dbch\_devicetype == 0x00000002)//DBT\_DEVTYP\_VOLUME  
                        \{  
                            DEV\_BROADCAST\_VOLUME dbv = (DEV\_BROADCAST\_VOLUME)Marshal.PtrToStructure(m.LParam, typeof(DEV\_BROADCAST\_VOLUME));  
                            if (dbv.dbcv\_flags == 0)  
                                RemoveVolumes(GetVolumes(dbv.dbcv\_unitmask));  
                        \}  
                        break;  
                    \}  
            \}  
        \}  
        base.DefWndProc(ref m);  
    \}  
    /// 根据驱动器掩码返回驱动器号数组  
    /// </summary>  
    /// <param name="Mask">掩码</param>  
    /// <returns>返回驱动器号数组</returns>  
    public static char\[\] GetVolumes(UInt32 Mask)  
    \{  
        List<char> Volumes = new List<char>();
        for (int i = 0; i < 32; i++)  
        \{  
            uint p = (uint)Math.Pow(2, i);  
            if ((p | Mask) == p)

{
Volumes.Add((char)(‘’A’’ + i));
}
}

return Volumes.ToArray();
}

public void AddVolumes(char[] Volumes)
{
foreach (char volume in Volumes)
listBox1.Items.Add(volume);
}

public void RemoveVolumes(char[] Volumes)
{
foreach (char volume in Volumes)
listBox1.Items.Remove(volume);
}

}
}