十七、责任链模式

有多个对象，每个对象持有对下一个对象的引用，这样就会形成一条链，请求在这条链上传递，直到某一对象决定处理该请求。但是发出者并不清楚到底最终那个对象会处理该请求，所以，责任链模式可以实现，在隐瞒客户端的情况下，对系统进行动态的调整。先看看关系图：

十七、责任链模式

java版：

package com.shuang.chain;

public abstract class AbstractHandler {
	private Handler handler;
	public Handler getHandler() {
		return handler;
	}

	public void setHandler(Handler handler){
		this.handler = handler;
	}
}

package com.shuang.chain;

public interface Handler {
	public void operator();
}

package com.shuang.chain;

public class MyHandler extends AbstractHandler implements Handler {
	private String name;

	public MyHandler(String name) {
		this.name = name;
	}

	@Override
	public void operator() {
		System.out.println(name + "deal!");
		if (getHandler() != null) {
			getHandler().operator();
		}
	}

}

package com.shuang.chain;

public class Test {
	public static void main(String[] args) {
		MyHandler h1 = new MyHandler("h1");
		MyHandler h2 = new MyHandler("h2");
		MyHandler h3 = new MyHandler("h3");
		
		h1.setHandler(h2);
		h2.setHandler(h3);
		
		h1.operator();
	}
}

c++版：

#include<iostream>
using namespace std;
class CarHandle
{
public:
	virtual void HandleCar()=0;
	void setNextHandle(CarHandle *handle)
	{
		m_handle = handle;
	}
protected:
	CarHandle *m_handle;
};
class HeadCarHandle:public CarHandle
{
public:
	virtual void HandleCar()
	{
		cout<<"造车头"<<endl;
		if (m_handle != NULL)
		{
			m_handle->HandleCar();
		}
	}
};
class BodyCarHandle:public CarHandle
{
public:
	virtual void HandleCar()
	{
		cout<<"造车身"<<endl;
		if (m_handle != NULL)
		{
			m_handle->HandleCar();
		}
	}
};
class TailCarHandle:public CarHandle
{
public:
	virtual void HandleCar()
	{
		cout<<"造车尾"<<endl;
		if (m_handle != NULL)
		{
			m_handle->HandleCar();
		}
	}
};
int main()
{
	CarHandle *headHandle = new HeadCarHandle;
	CarHandle *bodyHandle = new BodyCarHandle;
	CarHandle *tailHandle = new TailCarHandle;

	headHandle->setNextHandle(bodyHandle);
	bodyHandle->setNextHandle(tailHandle);
	tailHandle->setNextHandle(NULL);
	
	headHandle->HandleCar();

	delete headHandle;
	delete bodyHandle;
	delete tailHandle;
	system("pause");
	return 0;
}

十七、责任链模式

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