C++实现简单插件机制原理解析

#ifndef    __OBJECT_HPP__
#define  　　__OBJECT_HPP__

class Object
{
public:
  Object() {}
  virtual ~Object() {}
  virtual int Dump() = 0;
};

#endif    //__OBJECT_HPP__

#ifndef    __TESTOBJECT_HPP__
#define  　　__TESTOBJECT_HPP__

#include  "Object.hpp"

class TestObject : public Object
{
public:
  virtual int Dump();
};

#endif    //__TESTOBJECT_HPP__

#include  "TestObject.hpp"
#include  <iostream>

extern "C"
{
  void *Instance()
  {
    return new TestObject;
  }
}

int TestObject::Dump()
{
  std::cout << "class name:TestObject  function name:Dump()" << std::endl;
  return 0;
}

#include  <dlfcn.h>
#include  <iostream>
#include  "Object.hpp"

typedef Object *Instance();

int main()
{
  void *handle = dlopen("./libto.so", RTLD_LAZY);
  if(!handle)
  {
    std::cout << dlerror() << std::endl;
    return 1;
  }

  Instance *GetInstance = (Instance *)dlsym(handle, "Instance");
  if(!GetInstance)
  {
    std::cout << "Error Instance function" << std::endl;
    return 1;
  }

  Object *obj = GetInstance();
  if(0 != obj)
  {
    obj->Dump();
  }

  delete obj;
  dlclose(handle);

  return 0;
}

SOURCE=TestObject.cpp
makeso:${SOURCE}
  g++ -fPIC -shared $^ -o libto.so

main:
  g++ -o main -ldl main.cpp

clean:
  rm -rf main *.o *.so

all:makeso main

[kiven@localhost plugin]$ make all
g++ -fPIC -shared TestObject.cpp -o libto.so
g++ -o main -ldl main.cpp
[kiven@localhost plugin]$ ./main
class name:TestObject  function name:Dump()
[kiven@localhost plugin]$