设计模式读书笔记：Chain of Responsibility（责任链）

2015-07-10 17:30:18

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意图：

使多个对象都有机会处理请求，从而避免请求的发送者和接收者之间的耦合关系。将这些对象连成一条链，并沿着这条链传递该请求，直到有一个对象处理它为止。

结构图：来自 《23种设计模式 - 郗晓勇》

实现：https://github.com/panshiqu/patterns/tree/master/ChainOfResponsibility

Handle

namespace NS_CHAINOFRESPONSIBILITY {

class Handle {
public:
	Handle(Handle *successor) : _successor(successor) {}
	virtual ~Handle() {}
	virtual void HandleRequest(int request) = 0;

	Handle *getSuccessor(void)	{ return _successor; }

private:
	Handle *_successor;
};

} /* namespace NS_CHAINOFRESPONSIBILITY */

ConcreteHandle1

#include <iostream>
#include "Handle.h"

namespace NS_CHAINOFRESPONSIBILITY {

class ConcreteHandle1 : public Handle
{
public:
	ConcreteHandle1(Handle *successor) : Handle(successor) {}
	virtual ~ConcreteHandle1() {}
	virtual void HandleRequest(int request)
	{
		std::cout << "HandleRequest: " << request << std::endl;
	}
};

} /* namespace NS_CHAINOFRESPONSIBILITY */

ConcreteHandle2

#include <iostream>
#include "Handle.h"

namespace NS_CHAINOFRESPONSIBILITY {

class ConcreteHandle2 : public Handle
{
public:
	ConcreteHandle2(Handle *successor) : Handle(successor) {}
	virtual ~ConcreteHandle2() {}
	virtual void HandleRequest(int request)
	{
		if (request == 100)
		{
			std::cout << "Handle 100 Request." << std::endl;
		}
		else
		{
			if (getSuccessor())
				getSuccessor()->HandleRequest(request);
		}
	}
};

} /* namespace NS_CHAINOFRESPONSIBILITY */

main

#include "ChainOfResponsibility/ConcreteHandle1.h"
#include "ChainOfResponsibility/ConcreteHandle2.h"
using namespace NS_CHAINOFRESPONSIBILITY;
int main(void)
{
	ConcreteHandle1 ch1(0);
	ConcreteHandle2 ch2(&ch1);
	ch2.HandleRequest(100);
	ch2.HandleRequest(0);
}

附加：