QT 创建共享动态库和使用动态库

目录

 

1.创建共享动态库

1.1 新建工程，选择"Library"->C++库，点击"Choose"

1.2 选择类型"共享库"，下拉列表里有“共享库”，“静态链接库”，“Qt plugin”，本文选择“共享库”。然后输入动态库名称，此例我使用“Library”，点击"下一步"

1.3 选择构建套件，本例选择mingw 32bit，点击"下一步"

1.4 选择动态库需要的模块，本例中默认选择，点击"下一步"

1.5 详情提示，这里可以修改类名和头文件源文件名，点击"下一步"

1.6 项目管理界面，保持默认即可，点击"完成"按钮

1.7 上一步点击"完成后",会生成动态库程序

1.8 点击编译按钮

2.使用共享动态库

2.1 创建可执行程序

2.2 设置头文件路径和lib库路径

2.2.1 生成工程后，我们首先把动态库的头文件copy过来。

2.2.2 把lib库和动态库也要copy过来

2.2.3 打开testdll.pro,设置动态库头文件和lib库的路径

2.3 使用函数接口

2.4 将动态库copy到可执行文件路径下

end

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1.创建共享动态库

1.1 新建工程，选择"Library"->C++库，点击"Choose"

1.2 选择类型"共享库"，下拉列表里有“共享库”，“静态链接库”，“Qt plugin”，本文选择“共享库”。然后输入动态库名称，此例我使用“Library”，点击"下一步"

1.3 选择构建套件，本例选择mingw 32bit，点击"下一步"

1.4 选择动态库需要的模块，本例中默认选择，点击"下一步"

1.5 详情提示，这里可以修改类名和头文件源文件名，点击"下一步"

1.6 项目管理界面，保持默认即可，点击"完成"按钮

1.7 上一步点击"完成后",会生成动态库程序

生成的目录结构如下图：

其中library.h和library_global.h为头文件，我们可以把library_global.h文件的内容copy到library.h中，这样我们在使用动态库时只需要包含library.h即可。

library.pro

#-------------------------------------------------
#
# Project created by QtCreator 2019-08-21T12:56:02
#
#-------------------------------------------------

QT       -= gui

TARGET = library
TEMPLATE = lib

DEFINES += LIBRARY_LIBRARY

# The following define makes your compiler emit warnings if you use
# any feature of Qt which as been marked as deprecated (the exact warnings
# depend on your compiler). Please consult the documentation of the
# deprecated API in order to know how to port your code away from it.
DEFINES += QT_DEPRECATED_WARNINGS

# You can also make your code fail to compile if you use deprecated APIs.
# In order to do so, uncomment the following line.
# You can also select to disable deprecated APIs only up to a certain version of Qt.
#DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0x060000    # disables all the APIs deprecated before Qt 6.0.0

SOURCES += library.cpp

HEADERS += library.h\
        library_global.h

unix {
    target.path = /usr/lib
    INSTALLS += target
}

library_global.h

#ifndef LIBRARY_GLOBAL_H
#define LIBRARY_GLOBAL_H

#include <QtCore/qglobal.h>

#if defined(LIBRARY_LIBRARY)
#  define LIBRARYSHARED_EXPORT Q_DECL_EXPORT
#else
#  define LIBRARYSHARED_EXPORT Q_DECL_IMPORT
#endif

#endif // LIBRARY_GLOBAL_H

library.h

原始的library.h中只有一个空的类，我在这个文件中添加了几个方法，有普通函数接口

double LIBRARYSHARED_EXPORT Divide(int a,int b);

有成员函数接口 

int Multi(int a ,int b);

静态成员函数接口

 static int Add(int a,int b);

    static int Del(int a,int b);

#ifndef LIBRARY_H
#define LIBRARY_H

#include "library_global.h"

//函数接口
double LIBRARYSHARED_EXPORT Divide(int a,int b);

//类接口
class LIBRARYSHARED_EXPORT Library
{

public:
    Library();
    //类静态成员函数接口
    static int Add(int a,int b);
    static int Del(int a,int b);
    //类成员函数接口
    int Multi(int a ,int b);
};

#endif // LIBRARY_H

library.cpp

#include "library.h"

Library::Library()
{
}

int Library::Add(int a, int b)
{
    return a+b;
}

int Library::Del(int a, int b)
{
    return a - b;
}

int Library::Multi(int a, int b)
{
    return a*b;
}

double Divide(int a,int b)
{
    return (double)a/(double)b;
}

1.8 点击编译按钮

生成了三个文件liblibrary.a，liblibrary.dll,liblibrary.o，其中liblibrary.a，liblibrary.dll是使用动态库需要用到的。到此完成了共享动态库的创建。下面开始介绍共享动态库的使用。

2.使用共享动态库

2.1 创建可执行程序

点击完成，生成工程。

2.2 设置头文件路径和lib库路径

2.2.1 生成工程后，我们首先把动态库的头文件copy过来。

2.2.2 把lib库和动态库也要copy过来

2.2.3 打开testdll.pro,设置动态库头文件和lib库的路径

QT += core
QT -= gui

CONFIG += c++11

TARGET = dlltest
CONFIG += console
CONFIG -= app_bundle

TEMPLATE = app

SOURCES += main.cpp

# The following define makes your compiler emit warnings if you use
# any feature of Qt which as been marked deprecated (the exact warnings
# depend on your compiler). Please consult the documentation of the
# deprecated API in order to know how to port your code away from it.
DEFINES += QT_DEPRECATED_WARNINGS

# You can also make your code fail to compile if you use deprecated APIs.
# In order to do so, uncomment the following line.
# You can also select to disable deprecated APIs only up to a certain version of Qt.
#DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0x060000    # disables all the APIs deprecated before Qt 6.0.0
HEADERS += $$PWD/library/include/library_global.h \
            $$PWD/library/include/library.h

LIBS += $$PWD/library/lib/win32/release/liblibrary.a

 

2.3 使用函数接口

main.cpp

#include <QCoreApplication>
#include <QDebug>
#include "library/include/library.h"
int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);
    int num1 = 10;
    int num2 = 3;
    qDebug()<<"类静态成员函数接口"<<Library::Add(num1,num2);
    qDebug()<<"类静态成员函数接口"<<Library::Del(num1,num2);
    Library library;
    qDebug()<<"类成员函数接口"<<library.Multi(num1,num2);
    qDebug()<<"普通函数接口"<<Divide(num1,num2);
    return a.exec();
}

 

2.4 将动态库copy到可执行文件路径下

2.5 动态加载动态库，需要注意导出的函数名，可使用dumpbin查看

#include <QCoreApplication>
#include <QDebug>
#include <QString>
#include <QLibrary>
typedef int (*myfun)(int,int);//定义函数形式
typedef double (*myfun2)(int,int);
int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);

    QLibrary test_dll("library.dll");//加载动态库
    if(test_dll.load())
    {
        myfun2 fun2 = (myfun2)test_dll.resolve("Divide");//获取dll的函数
        if(fun2)
        {
            double result = fun2(10,3);
            qDebug()<<result;
        }
    }
    test_dll.unload();
    return a.exec();
}