121 lines
3.0 KiB
Markdown
121 lines
3.0 KiB
Markdown
|
### 使用c++11开发一个轻量级的Ioc容器
|
|||
|
|
Ioc容器具备两种能力，一种是对象工厂，不仅可以创建所有的对象，还可以根据配置去创建对象；另一种能力是可以去创建依赖对象，应有不需要直接创建对象，由Ioc容器去创建，实现控制反转。<br>
|
|||
|
|
实现Ioc容器需要解决三个问题，第一个问题是创建所有类型的对象，第二个问题是类型擦除，第三个问题是如何创建依赖对象。
|
|||
|
|
|
|||
|
|
#### 类型擦除的常用方法
|
|||
|
|
类型擦除就是讲原有类型消除或者隐藏。常用的方法有：
|
|||
|
|
1. 通过多态来擦除类型
|
|||
|
|
2. 通过模板来擦除类型
|
|||
|
|
3. 通过某种类型的模板容器擦除类型(Variant)
|
|||
|
|
4. 通过某种通用类型来擦除类型(any)
|
|||
|
|
5. 通过闭包来擦除类型（通过模板函数，将数值包入函数中，再包入std::function）
|
|||
|
|
```
|
|||
|
|
#pragma once
|
|||
|
|
#include<string>
|
|||
|
|
#include<unordered_map>
|
|||
|
|
#include<memory>
|
|||
|
|
#include<functional>
|
|||
|
|
using namespace std;
|
|||
|
|
#include<Any.hpp>
|
|||
|
|
#include <NonCopyable.hpp>
|
|||
|
|
|
|||
|
|
class IocContainer : NonCopyable
|
|||
|
|
{
|
|||
|
|
public:
|
|||
|
|
IocContainer(void){}
|
|||
|
|
~IocContainer(void){}
|
|||
|
|
|
|||
|
|
template<class T, typename Depend, typename... Args>
|
|||
|
|
void RegisterType(const string& strKey)
|
|||
|
|
{
|
|||
|
|
std::function<T* (Args...)> function = [](Args... args){ return new T(new Depend(args...)); };//通过闭包擦除了参数类型
|
|||
|
|
RegisterType(strKey, function);
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
template<class T, typename... Args>
|
|||
|
|
T* Resolve(const string& strKey, Args... args)
|
|||
|
|
{
|
|||
|
|
if (m_creatorMap.find(strKey) == m_creatorMap.end())
|
|||
|
|
returnnullptr;
|
|||
|
|
|
|||
|
|
Any resolver = m_creatorMap[strKey];
|
|||
|
|
std::function<T* (Args...)> function = resolver.AnyCast<std::function<T* (Args...)>>();
|
|||
|
|
|
|||
|
|
return function(args...);
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
template<class T, typename... Args>
|
|||
|
|
std::shared_ptr<T> ResolveShared(const string& strKey, Args... args)
|
|||
|
|
{
|
|||
|
|
T* t = Resolve<T>(strKey, args...);
|
|||
|
|
|
|||
|
|
return std::shared_ptr<T>(t);
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
private:
|
|||
|
|
void RegisterType(const string& strKey, Any constructor)
|
|||
|
|
{
|
|||
|
|
if (m_creatorMap.find(strKey) != m_creatorMap.end())
|
|||
|
|
throw std::invalid_argument("this key has already exist!");
|
|||
|
|
|
|||
|
|
//通过Any擦除了不同类型的构造器
|
|||
|
|
m_creatorMap.emplace(strKey, constructor);
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
private:
|
|||
|
|
unordered_map<string, Any> m_creatorMap;
|
|||
|
|
};
|
|||
|
|
/*test code
|
|||
|
|
struct Base
|
|||
|
|
{
|
|||
|
|
virtual void Func(){}
|
|||
|
|
virtual ~Base(){}
|
|||
|
|
};
|
|||
|
|
struct DerivedB : public Base
|
|||
|
|
{
|
|||
|
|
DerivedB(int a, double b):m_a(a),m_b(b)
|
|||
|
|
{
|
|||
|
|
}
|
|||
|
|
void Func()override
|
|||
|
|
{
|
|||
|
|
cout<<m_a+m_b<<endl;
|
|||
|
|
}
|
|||
|
|
private:
|
|||
|
|
int m_a;
|
|||
|
|
double m_b;
|
|||
|
|
};
|
|||
|
|
struct DerivedC : public Base
|
|||
|
|
{
|
|||
|
|
};
|
|||
|
|
struct A
|
|||
|
|
{
|
|||
|
|
A(Base * ptr) :m_ptr(ptr)
|
|||
|
|
{
|
|||
|
|
}
|
|||
|
|
void Func()
|
|||
|
|
{
|
|||
|
|
m_ptr->Func();
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
~A()
|
|||
|
|
{
|
|||
|
|
if(m_ptr!=nullptr)
|
|||
|
|
{
|
|||
|
|
delete m_ptr;
|
|||
|
|
m_ptr = nullptr;
|
|||
|
|
}
|
|||
|
|
}
|
|||
|
|
private:
|
|||
|
|
Base * m_ptr;
|
|||
|
|
};
|
|||
|
|
void TestIoc()
|
|||
|
|
{
|
|||
|
|
IocContainer ioc;
|
|||
|
|
ioc.RegisterType<A, DerivedC>(“C”); //配置依赖关系
|
|||
|
|
auto c = ioc.ResolveShared<A>(“C”);
|
|||
|
|
ioc.RegisterType<A, DerivedB, int, double>(“C”); //注册时要注意DerivedB的参数int和double
|
|||
|
|
auto b = ioc.ResolveShared<A>(“C”, 1, 2.0); //还要传入参数
|
|||
|
|
b->Func();
|
|||
|
|
}
|
|||
|
|
*/
|
|||
|
|
```
|