Qt提供了QAbstractNativeEventFilter来实现本地时间得过滤，通过对本地事件的检测，判断usb热插拔；(这里是windows 的例子);
首先，以QWidget, QAbstractNativeEventFilter为基类建立子类，重定义nativeEventFilter：
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virtual bool nativeEventFilter(const QByteArray &eventType, void *message, long *result);
譬如：建立UDisk类， class UDisk : public QWidget, public QAbstractNativeEventFilter{}
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bool UDisk::nativeEventFilter(const QByteArray &eventType, void *message, long *result)
{
MSG* msg = reinterpret_cast(message);
int msgType = msg->message;
if(msgType == WM_DEVICECHANGE) { // 消息类型， 这里是设备变动；
PDEV_BROADCAST_HDR lpdb = (PDEV_BROADCAST_HDR)msg->lParam;
switch (msg->wParam) {
case DBT_DEVICEARRIVAL:
if(lpdb->dbch_devicetype == DBT_DEVTYP_VOLUME) {
PDEV_BROADCAST_VOLUME lpdbv = (PDEV_BROADCAST_VOLUME)lpdb;
if(lpdbv->dbcv_flags ==0) {
QString USBDisk = QString(this->deviceMask(lpdbv ->dbcv_unitmask)) + ":/";
emit sigUDiskCome(USBDisk);
}
}
break;
case DBT_DEVICEREMOVECOMPLETE:
if(lpdb->dbch_devicetype == DBT_DEVTYP_VOLUME) {
PDEV_BROADCAST_VOLUME lpdbv = (PDEV_BROADCAST_VOLUME)lpdb;
if(lpdbv->dbcv_flags == 0) {
QString USBDisk = QString(this->deviceMask(lpdbv ->dbcv_unitmask)) +":/";
emit sigUDiskRemove(USBDisk);
}
}
break;
case DBT_DEVNODES_CHANGED:
break;
default:
break;
}
}
return QWidget::nativeEvent(eventType, message, result);
}
在主程序中，还需要对该nativeEventFilter进行注册才能生效：
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UDisk *pDisk = new UDisk;
qApp->installNativeEventFilter(pDisk);
