21631级护卫舰服役数量:Qt 事件处理机制（上篇）

来源：百度文库编辑：偶看新闻时间：2024/05/05 01:33:41

本博文转载自：http://www.51cto.com/php/viewart.php?artID=272812

在Qt中，事件被封装成一个个对象，所有的事件均继承自抽象类QEvent. 接下来依次谈谈Qt中有谁来产生、分发、接受和处理事件。

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本篇来介绍Qt 事件处理机制。深入了解事件处理系统对于每个学习Qt人来说非常重要，可以说，Qt是以事件驱动的UI工具集。大家熟知Signals/Slots在多线程的实现也依赖于Qt的事件处理机制。

在Qt中，事件被封装成一个个对象，所有的事件均继承自抽象类QEvent. 接下来依次谈谈Qt中有谁来产生、分发、接受和处理事件：

1、谁来产生事件：最容易想到的是我们的输入设备，比如键盘、鼠标产生的

keyPressEvent，keyReleaseEvent，mousePressEvent，mouseReleaseEvent事件（他们被封装成QMouseEvent和QKeyEvent），这些事件来自于底层的操作系统，它们以异步的形式通知Qt事件处理系统，后文会仔细道来。当然Qt自己也会产生很多事件，比如QObject::startTimer()会触发QTimerEvent. 用户的程序可还以自己定制事件。

2、谁来接受和处理事件：答案是QObject。在Qt的内省机制剖析一文已经介绍QObject 类是整个Qt对象模型的心脏，事件处理机制是QObject三大职责（内存管理、内省(intropection)与事件处理制）之一。任何一个想要接受并处理事件的对象均须继承自QObject，可以选择重载QObject::event()函数或事件的处理权转给父类。

3、谁来负责分发事件：对于non-GUI的Qt程序，是由QCoreApplication负责将QEvent分发给QObject的子类-Receiver. 对于Qt GUI程序，由QApplication来负责。

接下来，将通过对代码的解析来看看QT是利用event loop从事件队列中获取用户输入事件，又是如何将事件转义成QEvents，并分发给相应的QObject处理。

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#include
#include "widget.h"
//Section 1
int main(int argc, char *argv[])
{
QApplication app(argc, argv);
Widget window; // Widget 继承自QWidget
window.show();
return app.exec(); // 进入Qpplication事件循环，见section 2
}
// Section 2:
int QApplication::exec()
{
//skip codes
//简单的交给QCoreApplication来处理事件循环=〉section 3
return QCoreApplication::exec();
}
// Section 3
int QCoreApplication::exec()
{
//得到当前Thread数据
QThreadData *threadData = self->d_func()->threadData;
if (threadData != QThreadData::current()) {
qWarning("%s::exec: Must be called from the main thread", self->metaObject()->className());
return -1;
}
//检查event loop是否已经创建
if (!threadData->eventLoops.isEmpty()) {
qWarning("QCoreApplication::exec: The event loop is already running");
return -1;
}
...
QEventLoop eventLoop;
self->d_func()->in_exec = true;
self->d_func()->aboutToQuitEmitted = false;
//委任QEventLoop 处理事件队列循环 ==> Section 4
int returnCode = eventLoop.exec();
....
}
return returnCode;
}
// Section 4
int QEventLoop::exec(ProcessEventsFlags flags)
{
//这里的实现代码不少，最为重要的是以下几行
Q_D(QEventLoop); // 访问QEventloop私有类实例d
try {
//只要没有遇见exit，循环派发事件
while (!d->exit)
processEvents(flags | WaitForMoreEvents | EventLoopExec);
} catch (...) {}
}
// Section 5
bool QEventLoop::processEvents(ProcessEventsFlags flags)
{
Q_D(QEventLoop);
if (!d->threadData->eventDispatcher)
return false;
if (flags & DeferredDeletion)
QCoreApplication::sendPostedEvents(0, QEvent::DeferredDelete);
//将事件派发给与平台相关的QAbstractEventDispatcher子类 =>Section 6
return d->threadData->eventDispatcher->processEvents(flags);
}
#include
#include "widget.h"
//Section 1
int main(int argc, char *argv[])
{
QApplication app(argc, argv);
Widget window; // Widget 继承自QWidget
window.show();
return app.exec(); // 进入Qpplication事件循环，见section 2
}
// Section 2:
int QApplication::exec()
{
//skip codes
//简单的交给QCoreApplication来处理事件循环=〉section 3
return QCoreApplication::exec();
}
// Section 3
int QCoreApplication::exec()
{
//得到当前Thread数据
QThreadData *threadData = self->d_func()->threadData;
if (threadData != QThreadData::current()) {
qWarning("%s::exec: Must be called from the main thread", self->metaObject()->className());
return -1;
}
//检查event loop是否已经创建
if (!threadData->eventLoops.isEmpty()) {
qWarning("QCoreApplication::exec: The event loop is already running");
return -1;
}
...
QEventLoop eventLoop;
self->d_func()->in_exec = true;
self->d_func()->aboutToQuitEmitted = false;
//委任QEventLoop 处理事件队列循环 ==> Section 4
int returnCode = eventLoop.exec();
....
}
return returnCode;
}
// Section 4
int QEventLoop::exec(ProcessEventsFlags flags)
{
//这里的实现代码不少，最为重要的是以下几行
Q_D(QEventLoop); // 访问QEventloop私有类实例d
try {
//只要没有遇见exit，循环派发事件
while (!d->exit)
processEvents(flags | WaitForMoreEvents | EventLoopExec);
} catch (...) {}
}
// Section 5
bool QEventLoop::processEvents(ProcessEventsFlags flags)
{
Q_D(QEventLoop);
if (!d->threadData->eventDispatcher)
return false;
if (flags & DeferredDeletion)
QCoreApplication::sendPostedEvents(0, QEvent::DeferredDelete);
//将事件派发给与平台相关的QAbstractEventDispatcher子类 =>Section 6
return d->threadData->eventDispatcher->processEvents(flags);
}
// Section 6，QTDIR\src\corelib\kernel\qeventdispatcher_win.cpp
// 这段代码是完成与windows平台相关的windows c++。以跨平台著称的Qt同时也提供了对Symiban,Unix等平台的消息派发支持
// 其事现分别封装在QEventDispatcherSymbian和QEventDispatcherUNIX
// QEventDispatcherWin32派生自QAbstractEventDispatcher.
bool QEventDispatcherWin32::processEvents(QEventLoop::ProcessEventsFlags flags)
{
Q_D(QEventDispatcherWin32);
if (!d->internalHwnd)
createInternalHwnd();
d->interrupt = false;
emit awake();
bool canWait;
bool retVal = false;
bool seenWM_QT_SENDPOSTEDEVENTS = false;
bool needWM_QT_SENDPOSTEDEVENTS = false;
do {
DWORD waitRet = 0;
HANDLE pHandles[MAXIMUM_WAIT_OBJECTS - 1];
QVarLengthArray processedTimers;
while (!d->interrupt) {
DWORD nCount = d->winEventNotifierList.count();
Q_ASSERT(nCount < MAXIMUM_WAIT_OBJECTS - 1);
MSG msg;
bool haveMessage;
if (!(flags & QEventLoop::ExcludeUserInputEvents) && !d->queuedUserInputEvents.isEmpty()) {
// process queued user input events
haveMessage = true;
//从处理用户输入队列中取出一条事件
msg = d->queuedUserInputEvents.takeFirst();
} else if(!(flags & QEventLoop::ExcludeSocketNotifiers) && !d->queuedSocketEvents.isEmpty()) {
// 从处理socket队列中取出一条事件
haveMessage = true;
msg = d->queuedSocketEvents.takeFirst();
} else {
haveMessage = PeekMessage(&msg, 0, 0, 0, PM_REMOVE);
if (haveMessage && (flags & QEventLoop::ExcludeUserInputEvents)
&& ((msg.message >= WM_KEYFIRST
&& msg.message <= WM_KEYLAST)
|| (msg.message >= WM_MOUSEFIRST
&& msg.message <= WM_MOUSELAST)
|| msg.message == WM_MOUSEWHEEL
|| msg.message == WM_MOUSEHWHEEL
|| msg.message == WM_TOUCH
#ifndef QT_NO_GESTURES
|| msg.message == WM_GESTURE
|| msg.message == WM_GESTURENOTIFY
#endif
|| msg.message == WM_CLOSE)) {
// 用户输入事件入队列，待以后处理
haveMessage = false;
d->queuedUserInputEvents.append(msg);
}
if (haveMessage && (flags & QEventLoop::ExcludeSocketNotifiers)
&& (msg.message == WM_QT_SOCKETNOTIFIER && msg.hwnd == d->internalHwnd)) {
// socket 事件入队列，待以后处理
haveMessage = false;
d->queuedSocketEvents.append(msg);
}
}
....
if (!filterEvent(&msg)) {
TranslateMessage(&msg);
//将事件打包成message调用Windows API派发出去
//分发一个消息给窗口程序。消息被分发到回调函数，将消息传递给windows系统，windows处理完毕，会调用回调函数 => section 7
DispatchMessage(&msg);
}
}
}
} while (canWait);
...
return retVal;
}
// Section 6，QTDIR\src\corelib\kernel\qeventdispatcher_win.cpp
// 这段代码是完成与windows平台相关的windows c++。以跨平台著称的Qt同时也提供了对Symiban,Unix等平台的消息派发支持
// 其事现分别封装在QEventDispatcherSymbian和QEventDispatcherUNIX
// QEventDispatcherWin32派生自QAbstractEventDispatcher.
bool QEventDispatcherWin32::processEvents(QEventLoop::ProcessEventsFlags flags)
{
Q_D(QEventDispatcherWin32);
if (!d->internalHwnd)
createInternalHwnd();
d->interrupt = false;
emit awake();
bool canWait;
bool retVal = false;
bool seenWM_QT_SENDPOSTEDEVENTS = false;
bool needWM_QT_SENDPOSTEDEVENTS = false;
do {
DWORD waitRet = 0;
HANDLE pHandles[MAXIMUM_WAIT_OBJECTS - 1];
QVarLengthArray processedTimers;
while (!d->interrupt) {
DWORD nCount = d->winEventNotifierList.count();
Q_ASSERT(nCount < MAXIMUM_WAIT_OBJECTS - 1);
MSG msg;
bool haveMessage;
if (!(flags & QEventLoop::ExcludeUserInputEvents) && !d->queuedUserInputEvents.isEmpty()) {
// process queued user input events
haveMessage = true;
//从处理用户输入队列中取出一条事件
msg = d->queuedUserInputEvents.takeFirst();
} else if(!(flags & QEventLoop::ExcludeSocketNotifiers) && !d->queuedSocketEvents.isEmpty()) {
// 从处理socket队列中取出一条事件
haveMessage = true;
msg = d->queuedSocketEvents.takeFirst();
} else {
haveMessage = PeekMessage(&msg, 0, 0, 0, PM_REMOVE);
if (haveMessage && (flags & QEventLoop::ExcludeUserInputEvents)
&& ((msg.message >= WM_KEYFIRST
&& msg.message <= WM_KEYLAST)
|| (msg.message >= WM_MOUSEFIRST
&& msg.message <= WM_MOUSELAST)
|| msg.message == WM_MOUSEWHEEL
|| msg.message == WM_MOUSEHWHEEL
|| msg.message == WM_TOUCH
#ifndef QT_NO_GESTURES
|| msg.message == WM_GESTURE
|| msg.message == WM_GESTURENOTIFY
#endif
|| msg.message == WM_CLOSE)) {
// 用户输入事件入队列，待以后处理
haveMessage = false;
d->queuedUserInputEvents.append(msg);
}
if (haveMessage && (flags & QEventLoop::ExcludeSocketNotifiers)
&& (msg.message == WM_QT_SOCKETNOTIFIER && msg.hwnd == d->internalHwnd)) {
// socket 事件入队列，待以后处理
haveMessage = false;
d->queuedSocketEvents.append(msg);
}
}
....
if (!filterEvent(&msg)) {
TranslateMessage(&msg);
//将事件打包成message调用Windows API派发出去
//分发一个消息给窗口程序。消息被分发到回调函数，将消息传递给windows系统，windows处理完毕，会调用回调函数 => section 7
DispatchMessage(&msg);
}
}
}
} while (canWait);
...
return retVal;
}
// Section 7 windows窗口回调函数定义在QTDIR\src\gui\kernel\qapplication_win.cpp
extern "C" LRESULT QT_WIN_CALLBACK QtWndProc(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
...
//将消息重新封装成QEvent的子类QMouseEvent ==> Section 8
result = widget->translateMouseEvent(msg);
...
}
// Section 7 windows窗口回调函数定义在QTDIR\src\gui\kernel\qapplication_win.cpp
extern "C" LRESULT QT_WIN_CALLBACK QtWndProc(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
...
//将消息重新封装成QEvent的子类QMouseEvent ==> Section 8
result = widget->translateMouseEvent(msg);
...
}

    #include <QApplication>         #include "widget.h"         //Section 1         int main(int argc, char *argv[])         {             QApplication app(argc, argv);             Widget window;  // Widget 继承自QWidget             window.show();             return app.exec(); // 进入Qpplication事件循环，见section 2         }         // Section 2:          int QApplication::exec()         {            //skip codes            //简单的交给QCoreApplication来处理事件循环=〉section 3            return QCoreApplication::exec();         }         // Section 3         int QCoreApplication::exec()         {             //得到当前Thread数据             QThreadData *threadData = self->d_func()->threadData;             if (threadData != QThreadData::current()) {                 qWarning("%s::exec: Must be called from the main thread", self->metaObject()->className());                 return -1;             }             //检查event loop是否已经创建             if (!threadData->eventLoops.isEmpty()) {                 qWarning("QCoreApplication::exec: The event loop is already running");                 return -1;             }             ...             QEventLoop eventLoop;             self->d_func()->in_exec = true;             self->d_func()->aboutToQuitEmitted = false;             //委任QEventLoop 处理事件队列循环 ==> Section 4             int returnCode = eventLoop.exec();             ....             }             return returnCode;         }         // Section 4         int QEventLoop::exec(ProcessEventsFlags flags)         {            //这里的实现代码不少，最为重要的是以下几行            Q_D(QEventLoop); // 访问QEventloop私有类实例d                 try {                 //只要没有遇见exit，循环派发事件                 while (!d->exit)                     processEvents(flags | WaitForMoreEvents | EventLoopExec);             } catch (...) {}         }         // Section 5         bool QEventLoop::processEvents(ProcessEventsFlags flags)         {             Q_D(QEventLoop);             if (!d->threadData->eventDispatcher)                 return false;             if (flags & DeferredDeletion)                 QCoreApplication::sendPostedEvents(0, QEvent::DeferredDelete);             //将事件派发给与平台相关的QAbstractEventDispatcher子类 =>Section 6             return d->threadData->eventDispatcher->processEvents(flags);         }        #include <QApplication>     #include "widget.h"      //Section 1      int main(int argc, char *argv[])      {          QApplication app(argc, argv);          Widget window;  // Widget 继承自QWidget          window.show();          return app.exec(); // 进入Qpplication事件循环，见section 2      }      // Section 2:       int QApplication::exec()      {         //skip codes         //简单的交给QCoreApplication来处理事件循环=〉section 3         return QCoreApplication::exec();      }      // Section 3      int QCoreApplication::exec()      {          //得到当前Thread数据          QThreadData *threadData = self->d_func()->threadData;          if (threadData != QThreadData::current()) {              qWarning("%s::exec: Must be called from the main thread", self->metaObject()->className());              return -1;          }          //检查event loop是否已经创建          if (!threadData->eventLoops.isEmpty()) {              qWarning("QCoreApplication::exec: The event loop is already running");              return -1;          }          ...          QEventLoop eventLoop;          self->d_func()->in_exec = true;          self->d_func()->aboutToQuitEmitted = false;          //委任QEventLoop 处理事件队列循环 ==> Section 4          int returnCode = eventLoop.exec();          ....          }          return returnCode;      }      // Section 4      int QEventLoop::exec(ProcessEventsFlags flags)      {         //这里的实现代码不少，最为重要的是以下几行         Q_D(QEventLoop); // 访问QEventloop私有类实例d              try {              //只要没有遇见exit，循环派发事件              while (!d->exit)                  processEvents(flags | WaitForMoreEvents | EventLoopExec);          } catch (...) {}      }      // Section 5      bool QEventLoop::processEvents(ProcessEventsFlags flags)      {          Q_D(QEventLoop);          if (!d->threadData->eventDispatcher)              return false;          if (flags & DeferredDeletion)              QCoreApplication::sendPostedEvents(0, QEvent::DeferredDelete);          //将事件派发给与平台相关的QAbstractEventDispatcher子类 =>Section 6          return d->threadData->eventDispatcher->processEvents(flags);      }             // Section 6，QTDIR\src\corelib\kernel\qeventdispatcher_win.cpp         // 这段代码是完成与windows平台相关的windows c++。 以跨平台著称的Qt同时也提供了对Symiban,Unix等平台的消息派发支持         // 其事现分别封装在QEventDispatcherSymbian和QEventDispatcherUNIX         // QEventDispatcherWin32派生自QAbstractEventDispatcher.         bool QEventDispatcherWin32::processEvents(QEventLoop::ProcessEventsFlags flags)         {             Q_D(QEventDispatcherWin32);             if (!d->internalHwnd)                 createInternalHwnd();             d->interrupt = false;             emit awake();             bool canWait;             bool retVal = false;             bool seenWM_QT_SENDPOSTEDEVENTS = false;             bool needWM_QT_SENDPOSTEDEVENTS = false;             do {                 DWORD waitRet = 0;                 HANDLE pHandles[MAXIMUM_WAIT_OBJECTS - 1];                 QVarLengthArray<MSG> processedTimers;                 while (!d->interrupt) {                     DWORD nCount = d->winEventNotifierList.count();                     Q_ASSERT(nCount < MAXIMUM_WAIT_OBJECTS - 1);                     MSG msg;                     bool haveMessage;                     if (!(flags & QEventLoop::ExcludeUserInputEvents) && !d->queuedUserInputEvents.isEmpty()) {                         // process queued user input events                         haveMessage = true;                         //从处理用户输入队列中取出一条事件                         msg = d->queuedUserInputEvents.takeFirst();                     } else if(!(flags & QEventLoop::ExcludeSocketNotifiers) && !d->queuedSocketEvents.isEmpty()) {                         // 从处理socket队列中取出一条事件                         haveMessage = true;                         msg = d->queuedSocketEvents.takeFirst();                     } else {                         haveMessage = PeekMessage(&msg, 0, 0, 0, PM_REMOVE);                         if (haveMessage && (flags & QEventLoop::ExcludeUserInputEvents)                             && ((msg.message >= WM_KEYFIRST                                  && msg.message <= WM_KEYLAST)                                 || (msg.message >= WM_MOUSEFIRST                                     && msg.message <= WM_MOUSELAST)                                 || msg.message == WM_MOUSEWHEEL                                 || msg.message == WM_MOUSEHWHEEL                                 || msg.message == WM_TOUCH         #ifndef QT_NO_GESTURES                                 || msg.message == WM_GESTURE                                 || msg.message == WM_GESTURENOTIFY         #endif                                 || msg.message == WM_CLOSE)) {                             // 用户输入事件入队列，待以后处理                             haveMessage = false;                             d->queuedUserInputEvents.append(msg);                         }                         if (haveMessage && (flags & QEventLoop::ExcludeSocketNotifiers)                             && (msg.message == WM_QT_SOCKETNOTIFIER && msg.hwnd == d->internalHwnd)) {                             // socket 事件入队列，待以后处理                             haveMessage = false;                             d->queuedSocketEvents.append(msg);                         }                     }                     ....                         if (!filterEvent(&msg)) {                             TranslateMessage(&msg);                             //将事件打包成message调用Windows API派发出去                                //分发一个消息给窗口程序。消息被分发到回调函数，将消息传递给windows系统，windows处理完毕，会调用回调函数 => section 7                                               DispatchMessage(&msg);                         }                     }                              }             } while (canWait);               ...             return retVal;         }        // Section 6，QTDIR\src\corelib\kernel\qeventdispatcher_win.cpp      // 这段代码是完成与windows平台相关的windows c++。 以跨平台著称的Qt同时也提供了对Symiban,Unix等平台的消息派发支持      // 其事现分别封装在QEventDispatcherSymbian和QEventDispatcherUNIX      // QEventDispatcherWin32派生自QAbstractEventDispatcher.      bool QEventDispatcherWin32::processEvents(QEventLoop::ProcessEventsFlags flags)      {          Q_D(QEventDispatcherWin32);          if (!d->internalHwnd)              createInternalHwnd();          d->interrupt = false;          emit awake();          bool canWait;          bool retVal = false;          bool seenWM_QT_SENDPOSTEDEVENTS = false;          bool needWM_QT_SENDPOSTEDEVENTS = false;          do {              DWORD waitRet = 0;              HANDLE pHandles[MAXIMUM_WAIT_OBJECTS - 1];              QVarLengthArray<MSG> processedTimers;              while (!d->interrupt) {                  DWORD nCount = d->winEventNotifierList.count();                  Q_ASSERT(nCount < MAXIMUM_WAIT_OBJECTS - 1);                  MSG msg;                  bool haveMessage;                  if (!(flags & QEventLoop::ExcludeUserInputEvents) && !d->queuedUserInputEvents.isEmpty()) {                      // process queued user input events                      haveMessage = true;                      //从处理用户输入队列中取出一条事件                      msg = d->queuedUserInputEvents.takeFirst();                  } else if(!(flags & QEventLoop::ExcludeSocketNotifiers) && !d->queuedSocketEvents.isEmpty()) {                      // 从处理socket队列中取出一条事件                      haveMessage = true;                      msg = d->queuedSocketEvents.takeFirst();                  } else {                      haveMessage = PeekMessage(&msg, 0, 0, 0, PM_REMOVE);                      if (haveMessage && (flags & QEventLoop::ExcludeUserInputEvents)                          && ((msg.message >= WM_KEYFIRST                               && msg.message <= WM_KEYLAST)                              || (msg.message >= WM_MOUSEFIRST                                  && msg.message <= WM_MOUSELAST)                              || msg.message == WM_MOUSEWHEEL                              || msg.message == WM_MOUSEHWHEEL                              || msg.message == WM_TOUCH      #ifndef QT_NO_GESTURES                              || msg.message == WM_GESTURE                              || msg.message == WM_GESTURENOTIFY      #endif                              || msg.message == WM_CLOSE)) {                          // 用户输入事件入队列，待以后处理                          haveMessage = false;                          d->queuedUserInputEvents.append(msg);                      }                      if (haveMessage && (flags & QEventLoop::ExcludeSocketNotifiers)                          && (msg.message == WM_QT_SOCKETNOTIFIER && msg.hwnd == d->internalHwnd)) {                          // socket 事件入队列，待以后处理                          haveMessage = false;                          d->queuedSocketEvents.append(msg);                      }                  }                  ....                      if (!filterEvent(&msg)) {                          TranslateMessage(&msg);                          //将事件打包成message调用Windows API派发出去                             //分发一个消息给窗口程序。消息被分发到回调函数，将消息传递给windows系统，windows处理完毕，会调用回调函数 => section 7                                            DispatchMessage(&msg);                      }                  }                           }          } while (canWait);            ...          return retVal;      }            // Section 7 windows窗口回调函数 定义在QTDIR\src\gui\kernel\qapplication_win.cpp         extern "C" LRESULT QT_WIN_CALLBACK QtWndProc(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)         {            ...            //将消息重新封装成QEvent的子类QMouseEvent ==> Section 8             result = widget->translateMouseEvent(msg);                ...         }                  // Section 7 windows窗口回调函数 定义在QTDIR\src\gui\kernel\qapplication_win.cpp      extern "C" LRESULT QT_WIN_CALLBACK QtWndProc(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)      {         ...         //将消息重新封装成QEvent的子类QMouseEvent ==> Section 8          result = widget->translateMouseEvent(msg);             ...      }

从Section 1~Section7， Qt进入QApplication的event loop，经过层层委任，最终QEventloop的processEvent将通过与平台相关的QAbstractEventDispatcher的子类QEventDispatcherWin32获得用户的用户输入事件，并将其打包成message后，通过标准Windows API ，把消息传递给了Windows OS，Windows OS得到通知后回调QtWndProc, 至此事件的分发与处理完成了一半的路程。

小结：Qt 事件处理机制（上篇）的内容介绍完了，在下文中，我们将进一步讨论当我们收到来在Windows的回调后，事件又是怎么一步步打包成QEvent并通过QApplication分发给最终事件的接受和处理者QObject::event.请继续看Qt 事件处理机制（下篇）。最后希望本文能帮你解决问题！

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21631级护卫舰服役数量:Qt 事件处理机制 （上篇）

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