最近在学习qt国际化这一部分，现在有个问题就是动态切换。当我点击某个按钮之后，程序能够将所有需要翻译的字符串重新翻译，我现在谢了一个特别小的程序，但不知道为什么就是不翻译？求解。谢谢！！！

这个是代码：

//一个按钮****

#include "Dialog.h"

Dialog::Dialog(void)
{
button=new QPushButton(this);
updateUi();
}

Dialog::~Dialog(void)
{
}

void Dialog::updateUi()
{
button->setText(tr("change"));
this->setWindowTitle(tr("Dialog"));
}

void Dialog::Pushbutton_clicked()
{
emit SwitchLanguaged();
}

void Dialog::SwitchLanguaged()
{

}

void Dialog::changeEvent(QEvent *e)
{
QWidget::changeEvent(e);
switch(e->type())
{
case QEvent::LanguageChange:
updateUi();
break;
default:
break;
}
}

#pragma once
#include
#include
#include

class Dialog:public QDialog
{
public:
Dialog(void);
~Dialog(void);
void changeEvent(QEvent *);
void updateUi();

public:
QPushButton *button;
signals:
void SwitchLanguaged();

public slots:
//void SwitchLanguaged();
void Pushbutton_clicked();
};

# //主界面

#include
#include
#include
#include
#include
#include
#include
#include
#include
#include "mainwindow.h"
#include "Dialog.h"
MainWindow::MainWindow()
{
QWidget *widget=new QWidget;
setCentralWidget(widget);//设置中央Widget

infoLabel=new QLabel("Choose a menu option,or right-click to invoke action");
infoLabel->setAlignment(Qt::AlignCenter);//居中对齐
QVBoxLayout *layout=new QVBoxLayout;
layout->addWidget(infoLabel);

widget->setLayout(layout);

createActions();
createMenus();

QString msg="popup a menu by right-clicking.";
statusBar()->showMessage(msg);

setMinimumSize(160,160);//设置最小尺寸
resize(480,320);//设置尺寸

Dialog *d=new Dialog;
connect(d,SIGNAL(SwitchLanguaged()),this,SLOT(LanguageChanged()));
updateUi();

}

//创建Actions
void MainWindow::createActions()
{
newAct=new QAction("&New",this);
newAct->setShortcut(QKeySequence("Ctrl+N"));//设置快捷键
newAct->setStatusTip("New a file");//设置状态栏提示
connect(newAct,SIGNAL(triggered()),this,SLOT(newFile()));

     openAct = new QAction("&Open...", this); 
     openAct->setShortcut(tr("Ctrl+O")); 
     openAct->setStatusTip("Open an existing file"); 
     connect(openAct, SIGNAL(triggered()), this, SLOT(openFile()));    

     saveAct = new QAction("&Save", this); 
     saveAct->setShortcut(tr("Ctrl+S")); 
     saveAct->setStatusTip("save the    file"); 
     connect(saveAct, SIGNAL(triggered()), this, SLOT(saveFile()));             

     printAct = new QAction("&Print...", this); 
     printAct->setShortcut(tr("Ctrl+P")); 
     printAct->setStatusTip("Print the    file"); 
     connect(printAct, SIGNAL(triggered()), this, SLOT(printFile()));                     

     exitAct = new QAction("E&xit", this); 
     exitAct->setShortcut(tr("Ctrl+Q")); 
     exitAct->setStatusTip("Exit the Application."); 
     connect(exitAct, SIGNAL(triggered()), this, SLOT(close()));            

     boldAct = new QAction(tr("&Bold"), this); 
     boldAct->setCheckable(true);//可选择 
     boldAct->setShortcut(tr("Ctrl+B")); 
     boldAct->setStatusTip(tr("Make the text bold")); 
     connect(boldAct, SIGNAL(triggered()), this, SLOT(bold()));            
     QFont boldFont = boldAct->font(); 
     boldFont.setBold(true);//字体加粗 
     boldAct->setFont(boldFont);//设置字体 

     italicAct = new QAction(tr("&Italic"), this); 
     italicAct->setCheckable(true); 
     italicAct->setShortcut(tr("Ctrl+I")); 
     italicAct->setStatusTip(tr("Make the text italic")); 
     connect(italicAct, SIGNAL(triggered()), this, SLOT(italic())); 
     QFont italicFont = italicAct->font(); 
     italicFont.setItalic(true);//设置倾斜 
     italicAct->setFont(italicFont); 


     aboutAct=new QAction("&About",this); 
     aboutAct->setStatusTip("About the App"); 
     connect(aboutAct,SIGNAL(triggered()),this,SLOT(about())); 

}

//创建菜单
void MainWindow::createMenus()
{
//文件菜单
fileMenu=menuBar()->addMenu("&File");
fileMenu->addAction(newAct);
fileMenu->addAction(openAct);
fileMenu->addAction(saveAct);
fileMenu->addAction(printAct);
fileMenu->addSeparator();
fileMenu->addAction(exitAct);

//编辑菜单
editMenu=menuBar()->addMenu("&Edit");
formatMenu=editMenu->addMenu("&Format");
formatMenu->addAction(boldAct);
formatMenu->addAction(italicAct);

//帮助菜单
helpMenu=menuBar()->addMenu("&Help");
helpMenu->addAction(aboutAct);

//翻译
//tranMenu=menuBar()->addMenu(tr("Tran"));

//connect(

}

void MainWindow::newFile()
{
infoLabel->setText("InvokeFile|New");
}
void MainWindow::openFile()
{
infoLabel->setText("InvokeFile|Open");
}
void MainWindow::saveFile()
{
infoLabel->setText("InvokeFile|Save");
}

void MainWindow::printFile()
{
infoLabel->setText("InvokeFile|Print");
}

//关于对话框
void MainWindow::about()
{
infoLabel->setText("InvokeHelp|About");
QMessageBox::about(this,"About","How to createMenus");
}

void MainWindow::bold()
{
infoLabel->setText("InvokeEdit|Format|bold");
}

void MainWindow::italic()
{
infoLabel->setText("InvokeEdit|Format|italic");
}
//自定义部分
void MainWindow::LanguageChanged()
{
tran->load("cn.qm");
qApp->installTranslator(tran);
updateUi();

}
void MainWindow::updateUi()
{
setWindowTitle(tr("Menus"));
}
void MainWindow::changeEvent(QEvent *e)
{
QWidget::changeEvent(e);
switch(e->type())
{
case QEvent::LanguageChange:
updateUi();
break;
default:
break;
}
}

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include
#include
#include
#include
class QMenu;
class QAction;
class QLabel;

class MainWindow:public QMainWindow
{
Q_OBJECT
public:
MainWindow();
void changeEvent(QEvent *);
void updateUi();
public:
QTranslator *tran;//翻译文件

private slots:
void newFile();
void openFile();
void saveFile();
void printFile();
void about();
void bold();
void italic();
void LanguageChanged();
private:
QMenu* fileMenu;//文件菜单
QMenu* editMenu;//编辑菜单
QMenu* helpMenu;//帮助菜单
//QMenu* tranMenu;

QMenu* formatMenu;

QAction* newAct;//新建
QAction* openAct;//打开
QAction* saveAct;//保存
QAction* printAct;//打印
QAction* exitAct;//退出
QAction* boldAct;
QAction* italicAct;

QAction* aboutAct;//关于
QLabel* infoLabel;

void createActions();
void createMenus();

};

#endif // MAINWINDOW_H