在.NET中探测U盘的插入/拔出

快来打我* 2022-09-28 14:29 157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();  
![ExpandedSubBlockEnd.gif][]        \}  
![InBlock.gif][]  
![InBlock.gif][]        private void Form1\_Load(object sender, EventArgs e)  
![ExpandedSubBlockStart.gif][]![ContractedSubBlock.gif][]        ![dot.gif][]\{  
![InBlock.gif][]  
![ExpandedSubBlockEnd.gif][]        \}  
![InBlock.gif][]  
![InBlock.gif][]        \[StructLayout(LayoutKind.Sequential)\]  
![InBlock.gif][]        struct DEV\_BROADCAST\_HDR  
![ExpandedSubBlockStart.gif][]![ContractedSubBlock.gif][]        ![dot.gif][]\{  
![InBlock.gif][]            public UInt32 dbch\_size;  
![InBlock.gif][]            public UInt32 dbch\_devicetype;  
![InBlock.gif][]            public UInt32 dbch\_reserved;  
![ExpandedSubBlockEnd.gif][]        \}  
![InBlock.gif][]  
![InBlock.gif][]        \[StructLayout(LayoutKind.Sequential)\]  
![InBlock.gif][]        struct DEV\_BROADCAST\_VOLUME  
![ExpandedSubBlockStart.gif][]![ContractedSubBlock.gif][]        ![dot.gif][]\{  
![InBlock.gif][]            public UInt32 dbcv\_size;  
![InBlock.gif][]            public UInt32 dbcv\_devicetype;  
![InBlock.gif][]            public UInt32 dbcv\_reserved;  
![InBlock.gif][]            public UInt32 dbcv\_unitmask;  
![InBlock.gif][]            public UInt16 dbcv\_flags;  
![ExpandedSubBlockEnd.gif][]        \}  
 protected override void DefWndProc(ref Message m)  
![ExpandedSubBlockStart.gif][]![ContractedSubBlock.gif][]        ![dot.gif][]\{  
![InBlock.gif][]            if (m.Msg == 0x0219)//WM\_DEVICECHANGE  
![ExpandedSubBlockStart.gif][]![ContractedSubBlock.gif][]            ![dot.gif][]\{  
![InBlock.gif][]                switch (m.WParam.ToInt32())  
![ExpandedSubBlockStart.gif][]![ContractedSubBlock.gif][]                ![dot.gif][]\{  
![InBlock.gif][]                    case 0x8000://DBT\_DEVICEARRIVAL  
![ExpandedSubBlockStart.gif][]![ContractedSubBlock.gif][]                        ![dot.gif][]\{  
![InBlock.gif][]                            DEV\_BROADCAST\_HDR dbhdr = (DEV\_BROADCAST\_HDR)Marshal.PtrToStructure(m.LParam, typeof(DEV\_BROADCAST\_HDR));  
![InBlock.gif][]  
![InBlock.gif][]                            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)

\{  
![InBlock.gif][]                    Volumes.Add((char)(''A'' \+ i));  
![ExpandedSubBlockEnd.gif][]                \}  
![ExpandedSubBlockEnd.gif][]            \}  
![InBlock.gif][]  
![InBlock.gif][]            return Volumes.ToArray();  
![ExpandedSubBlockEnd.gif][]        \}  
![InBlock.gif][]  
![InBlock.gif][]        public void AddVolumes(char\[\] Volumes)  
![ExpandedSubBlockStart.gif][]![ContractedSubBlock.gif][]        ![dot.gif][]\{  
![InBlock.gif][]            foreach (char volume in Volumes)  
![InBlock.gif][]                listBox1.Items.Add(volume);  
![ExpandedSubBlockEnd.gif][]        \}  
![InBlock.gif][]  
![InBlock.gif][]        public void RemoveVolumes(char\[\] Volumes)  
![ExpandedSubBlockStart.gif][]![ContractedSubBlock.gif][]        ![dot.gif][]\{  
![InBlock.gif][]            foreach (char volume in Volumes)  
![InBlock.gif][]                listBox1.Items.Remove(volume);  
![ExpandedSubBlockEnd.gif][]        \}  
![InBlock.gif][]  
![ExpandedSubBlockEnd.gif][]    \}  
![ExpandedBlockEnd.gif][]\}

[ExpandedSubBlockEnd.gif]: /images/20220708/b71eaf6e8b074b61a63755262cf7504e.png
[InBlock.gif]: /images/20220708/5368e2d1c3f147879d00996e9af31ea2.png
[ExpandedSubBlockStart.gif]: http://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockStart.gif
[ContractedSubBlock.gif]: http://www.cnblogs.com/Images/OutliningIndicators/ContractedSubBlock.gif
[dot.gif]: /images/20220708/95f349d021924487bf1ac691f1d1a114.png
[ExpandedBlockEnd.gif]: /images/20220708/0b1ac19c52f543dba03cb195707dbbc7.png