大话设计模式10-组合模式-2020-9-24

1.组合模式简介

组合模式：将对象组合成树形结构来表示“部分-整体”的关系，组合模式使得单个对象和组合对象使用具有一致性。UML类图如下：

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2.实例

实现一个公司的办公管理系统，父公司下面可能既有子部门也有子公司。UML类图如下：

c++代码实现如下：

#include<exception>
#include <iostream>
#include<string>
#include<list>
using namespace std;
//10.组合模式：办公管理系统
class Component
{
public:
	Component(const string &istrName) :m_strName(istrName){};
	virtual ~Component(){}
	string getName(){ return m_strName; }
	virtual void addComponent(Component* ipCom) = 0;
	virtual Component* removeComponent(const string &istrName) = 0;
	virtual void display(int depth) = 0;
protected:
	string m_strName;
};

class ConcreteComponent :public Component
{
public:
	ConcreteComponent(const string &istrName) :Component(istrName){}
	void addComponent(Component* ipCom) override
	{
		m_coms.push_back(ipCom);
	}
	Component* removeComponent(const string &istrName)override
	{
		Component *pCom = NULL;
		for (auto itr = m_coms.begin(); itr != m_coms.end();++itr)
		{
			if ((*itr)->getName()==istrName)
			{
				pCom = *itr;
				m_coms.erase(itr);
				break;
			}
		}
		return pCom;
	}
	void display(int depth) override
	{
		string line(depth,'-');
		line += m_strName;
		cout << line << endl;
		for (auto itr = m_coms.begin(); itr != m_coms.end(); ++itr)
		{
			(*itr)->display(depth + 2);
		}
	}
private:
	list<Component *>m_coms;
};

class LeafComponent :public Component
{
public:
	LeafComponent(const string &istrName) :Component(istrName){};
	void addComponent(Component* ipCom)
	{
		cout << "部门不能增加子公司！" << endl;
	}
	Component *removeComponent(const string &istrName)
	{
		cout << "部门下没有子公司！" << endl;
		return NULL;
	}
	void display(int depth)
	{
		string line(depth,'-');
		line += m_strName;
		cout << line << endl;
	}
};

int main()
{
	ConcreteComponent root("北京总公司");
	LeafComponent leaf1("hr部");
	LeafComponent leaf2("技术部");
	LeafComponent leaf3("财务部");
	root.addComponent(&leaf1);
	root.addComponent(&leaf2);
	root.addComponent(&leaf3);
	ConcreteComponent childCom("武汉办事处");
	LeafComponent leaf4("武汉办事处hr部");
	LeafComponent leaf5("武汉办事处技术部");
	childCom.addComponent(&leaf4);
	childCom.addComponent(&leaf5);
	root.addComponent(&childCom);
	root.display(1);
	system("pause");
}

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