Qt 一步一步实现dll调用（附源码）

#ifndef MYSHOWTEST_H
#define MYSHOWTEST_H

#include <QDialog>

namespace Ui {
    class MyShowTest;
}

class MyShowTest : public QDialog
{
    Q_OBJECT

public:
    explicit MyShowTest(QWidget *parent = 0);
    ~MyShowTest();

private:
    Ui::MyShowTest *ui;
};

#endif // MYSHOWTEST_H

#ifndef MYTESTDLL_H
#define MYTESTDLL_H

#include "MyTestDll_global.h"
#include "qdialog.h"
class MYTESTDLLSHARED_EXPORT MyTestDll {
public:
    MyTestDll();
};
extern "C" Q_DECL_EXPORT int add(int a,int b);
extern "C" Q_DECL_EXPORT QDialog *showDialog();
#endif // MYTESTDLL_H

#include "myshowtest.h"
#include "ui_myshowtest.h"

MyShowTest::MyShowTest(QWidget *parent) :
    QDialog(parent),
    ui(new Ui::MyShowTest)
{
    ui->setupUi(this);
}

MyShowTest::~MyShowTest()
{
    delete ui;
}

#include "mytestdll.h"
#include "MyShowTest.h"

MyTestDll::MyTestDll()
{
}
int add(int a,int b)
{
  return a+b;
}
QDialog *showDialog()
{
    MyShowTest *ss=new MyShowTest();
    return ss;
}

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>

namespace Ui {
    class MainWindow;
}

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    explicit MainWindow(QWidget *parent = 0);
    ~MainWindow();

private:
    Ui::MainWindow *ui;

private slots:
    void on_pushButton_2_clicked();
    void on_pushButton_clicked();
};

#endif // MAINWINDOW_H

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include "qlibrary.h"
#include "qmessagebox.h"
#include "string.h"

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
}

MainWindow::~MainWindow()
{
    delete ui;
}
typedef int (*Fun)(int,int); //定义函数指针，以备调用
void MainWindow::on_pushButton_clicked()
{
   QLibrary mylib("MyTestDll.dll");   //声明所用到的dll文件
   int result;
   QString sresult;
   if (mylib.load())              //判断是否正确加载
   {
       Fun open=(Fun)mylib.resolve("add");    //援引 add() 函数
       if (open)                  //是否成功连接上 add() 函数
       {
            int s1=this->ui->lineEdit->text().toInt();
            int s2=this->ui->lineEdit_2->text().toInt();
            result=open(s1,s2);      //这里函数指针调用dll中的 add() 函数
            sresult=QString::number(result);
            this->ui->lineEdit_3->setText(sresult);
       }
   }
   else
   {
       QMessageBox::information(NULL,"NO","DLL is not loaded!");
   }

}
typedef QDialog *(*Funs)(); //定义函数指针，以备调用
void MainWindow::on_pushButton_2_clicked()
{
   //加载插件
   QLibrary mylib("MyTestDll.dll");   //声明所用到的dll文件
   if (mylib.load())              //判断是否正确加载
   {
       Funs open=(Funs)mylib.resolve("showDialog");    //援引 add() 函数
       if (open)                  //是否成功连接上 add() 函数
       {
           QDialog *form1= open();
           form1->show();
        }
    }
}