C ++在Linux平台上的运行时加载共享库和提取类实现 [英] C++ load shared library and extract class implementations at runtime on linux platform

问题描述

在C ++中，是否可以在执行时加载共享库？

In C++, is it possible to load a shared library at execution time?

我希望用户选择在运行时加载哪个共享库，而不需要重新编译整个程序。

I want the user to choose which shared library to be loaded at runtime, without recompiling the whole program.

dlopen（）是C的解决方案，但是我的程序是C ++ / Qt，而且提取的符号是Qt风格的类，

dlopen() is a solution for C, but my program is written is C++/Qt, and the symbol to extract are Qt-style class, is there a more "c++" way to do that.

推荐答案

您可以使用 QLibrary 两种方式。以下示例以两种不同的方式在运行时从共享库调用函数：

You can do it in Qt using QLibrary in two ways. The following example calls a function from a shared library at runtime in two different ways:

#include <QLibrary>
#include <QDebug>

class  Dynamic_library
{
public:
    Dynamic_library();
    virtual int sum( int len, int * data );
};

typedef Dynamic_library * (*get_object_func)();
typedef int (*call_sum_func)(int len , int * data);

int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);

    QLibrary library( "./dynamic_library" );
    library.load();
    if( !library.isLoaded() )
    {
        qDebug() << "Cannot load library.";
        return 0;
    }
    call_sum_func call_sum = (call_sum_func)library.resolve( "call_sum" );
    if( call_sum )
    {
        //Dynamic_library * obj=get_object();

        int * a=new int[3];
        a[0]=2;
        a[1]=3;
        a[2]=4;
        qDebug() << "sum of 2+3+4' = " << call_sum( 3, a ) <<"\n";

        delete [] a;
    }

    get_object_func get_object = (get_object_func)library.resolve( "get_object" );
    if( get_object )
    {
        Dynamic_library * obj=get_object();

        int * a=new int[3];
        a[0]=7;
        a[1]=8;
        a[2]=9;
        qDebug() << "sum of 7+8+9' = " << obj->sum(3, a );

        delete [] a;
    }

    return a.exec();
}

共享库的代码如下：

class DYNAMIC_LIBRARYSHARED_EXPORT Dynamic_library
{
public:
    Dynamic_library();
    virtual int sum( int len, int * data );
};

extern "C" Q_DECL_EXPORT Dynamic_library * get_object()
{
     return new Dynamic_library();
}

extern "C" Q_DECL_EXPORT int call_sum(int len, int * data)
{
     return Dynamic_library().sum(len,data);
}


Dynamic_library::Dynamic_library()
{

}

int Dynamic_library::sum( int len, int *data )
{
    int sum = 0;
    for(int i=0; i<len; ++i )
        sum += data[i];

    return sum;
}

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