usb 设备的插拔,是通过什么来通知到应用层的
时间: 2024-04-13 16:27:02 浏览: 35
USB设备的插拔是通过操作系统来通知到应用层的。当USB设备插入或拔出时,操作系统会检测到设备的变化,并向应用层发送相应的通知消息。这些通知消息可以通过操作系统提供的API或事件机制来获取,以便应用层能够进行相应的处理。具体的实现方式可能因操作系统而异,例如在Windows系统中可以使用WM_DEVICECHANGE消息或RegisterDeviceNotification函数来接收USB设备插拔的通知。
相关问题
Window监控USB设备插拔动作,C语言
要在Windows上监控USB设备的插拔动作,可以使用Windows API函数来实现。以下是一个使用C语言编写的示例代码:
```c
#include <Windows.h>
#include <Dbt.h>
#include <stdio.h>
LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
switch (message)
{
case WM_DEVICECHANGE:
{
PDEV_BROADCAST_HDR pBroadcastHdr = (PDEV_BROADCAST_HDR)lParam;
if (pBroadcastHdr != NULL)
{
switch (wParam)
{
case DBT_DEVICEARRIVAL:
{
PDEV_BROADCAST_DEVICEINTERFACE pBroadcastDevInterface = (PDEV_BROADCAST_DEVICEINTERFACE)pBroadcastHdr;
if (pBroadcastDevInterface->dbcc_devicetype == DBT_DEVTYP_DEVICEINTERFACE)
{
printf("USB device inserted\n");
// 在这里处理USB设备插入后的操作
}
break;
}
case DBT_DEVICEREMOVECOMPLETE:
{
PDEV_BROADCAST_DEVICEINTERFACE pBroadcastDevInterface = (PDEV_BROADCAST_DEVICEINTERFACE)pBroadcastHdr;
if (pBroadcastDevInterface->dbcc_devicetype == DBT_DEVTYP_DEVICEINTERFACE)
{
printf("USB device removed\n");
// 在这里处理USB设备拨出后的操作
}
break;
}
}
}
break;
}
default:
return DefWindowProc(hWnd, message, wParam, lParam);
}
return 0;
}
int main()
{
WNDCLASS wc = {0};
wc.lpfnWndProc = WndProc;
wc.hInstance = GetModuleHandle(NULL);
wc.lpszClassName = "USBDeviceMonitor";
if (!RegisterClass(&wc))
{
printf("Failed to register window class\n");
return 1;
}
HWND hWnd = CreateWindowEx(0, wc.lpszClassName, "", 0, 0, 0, 0, 0, HWND_MESSAGE, NULL, NULL, NULL);
if (hWnd == NULL)
{
printf("Failed to create window\n");
return 1;
}
DEV_BROADCAST_DEVICEINTERFACE notificationFilter = {0};
notificationFilter.dbcc_size = sizeof(DEV_BROADCAST_DEVICEINTERFACE);
notificationFilter.dbcc_devicetype = DBT_DEVTYP_DEVICEINTERFACE;
notificationFilter.dbcc_classguid = GUID_DEVINTERFACE_USB;
HDEVNOTIFY hDevNotify = RegisterDeviceNotification(hWnd, ¬ificationFilter, DEVICE_NOTIFY_WINDOW_HANDLE);
if (hDevNotify == NULL)
{
printf("Failed to register device notification\n");
return 1;
}
MSG msg;
while (GetMessage(&msg, NULL, 0, 0))
{
TranslateMessage(&msg);
DispatchMessage(&msg);
}
UnregisterDeviceNotification(hDevNotify);
DestroyWindow(hWnd);
return 0;
}
```
在上面的代码中,我们创建了一个窗口,并在窗口的回调函数`WndProc`中处理`WM_DEVICECHANGE`消息,该消息会在设备插拔时触发。通过检查`wParam`参数和设备类型,我们可以确定是设备插入还是拨出,并在相应的分支中执行相应的操作。
请注意,该示例代码是一个简化的示例,只演示了如何监控USB设备的插拔动作。在实际应用中,您可能需要根据需要进行更多的处理,例如打开和关闭设备、读取设备信息等等。
使用inotify获取usb设备插拔事件,请用C语言写出程序
以下是使用inotify获取USB设备插拔事件的C语言程序:
```c
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <sys/inotify.h>
#define EVENT_SIZE (sizeof (struct inotify_event))
#define BUF_LEN (1024 * (EVENT_SIZE + 16))
int main(int argc, char **argv)
{
int fd, wd;
char buf[BUF_LEN];
int len, i = 0;
char *p;
struct inotify_event *event;
fd = inotify_init();
if (fd < 0) {
perror("inotify_init");
return -1;
}
wd = inotify_add_watch(fd, "/dev/", IN_CREATE | IN_DELETE);
if (wd < 0) {
perror("inotify_add_watch");
return -1;
}
while (1) {
len = read(fd, buf, BUF_LEN);
if (len < 0) {
perror("read");
return -1;
}
i = 0;
while (i < len) {
event = (struct inotify_event *) &buf[i];
if (event->mask & IN_CREATE) {
if (event->mask & IN_ISDIR) {
printf("The directory %s was created.\n", event->name);
} else {
printf("The file %s was created.\n", event->name);
}
} else if (event->mask & IN_DELETE) {
if (event->mask & IN_ISDIR) {
printf("The directory %s was deleted.\n", event->name);
} else {
printf("The file %s was deleted.\n", event->name);
}
}
i += EVENT_SIZE + event->len;
}
}
inotify_rm_watch(fd, wd);
close(fd);
return 0;
}
```
该程序使用inotify机制监听/dev/目录下的IN_CREATE和IN_DELETE事件,当有USB设备插入或拔出时,会打印相应的消息。注意,该程序需要使用root权限运行。