DP上的定義:適配器模式將一個類的接口轉換成客戶希望的另外一個接口,使得原本由於接口不兼容而不能一起工作的那些類可以一起工作。它包括類適配器和對象適配器,本文針對的是對象適配器。舉個例子,在STL中就用到了適配器模式。STL實現了一種數據結構,稱爲雙端隊列(deque),支持前後兩段的插入與刪除。STL實現棧和隊列時,沒有從頭開始定義它們,而是直接使用雙端隊列實現的。這裏雙端隊列就扮演了適配器的角色。隊列用到了它的後端插入,前端刪除。而棧用到了它的後端插入,後端刪除。假設棧和隊列都是一種順序容器,有兩種操作:壓入和彈出。下面給出相應的UML圖,與DP上的圖差不多。
根據上面的UML圖,很容易給出實現。
- //雙端隊列
- class Deque
- {
- public:
- void push_back(int x) { cout<<"Deque push_back"<<endl; }
- void push_front(int x) { cout<<"Deque push_front"<<endl; }
- void pop_back() { cout<<"Deque pop_back"<<endl; }
- void pop_front() { cout<<"Deque pop_front"<<endl; }
- };
- //順序容器
- class Sequence
- {
- public:
- virtual void push(int x) = 0;
- virtual void pop() = 0;
- };
- //棧
- class Stack: public Sequence
- {
- public:
- void push(int x) { deque.push_back(x); }
- void pop() { deque.pop_back(); }
- private:
- Deque deque; //雙端隊列
- };
- //隊列
- class Queue: public Sequence
- {
- public:
- void push(int x) { deque.push_back(x); }
- void pop() { deque.pop_front(); }
- private:
- Deque deque; //雙端隊列
- };
- //雙端隊列
- class Deque
- {
- public:
- void push_back(int x) { cout<<"Deque push_back"<<endl; }
- void push_front(int x) { cout<<"Deque push_front"<<endl; }
- void pop_back() { cout<<"Deque pop_back"<<endl; }
- void pop_front() { cout<<"Deque pop_front"<<endl; }
- };
- //順序容器
- class Sequence
- {
- public:
- virtual void push(int x) = 0;
- virtual void pop() = 0;
- };
- //棧
- class Stack: public Sequence
- {
- public:
- void push(int x) { deque.push_back(x); }
- void pop() { deque.pop_back(); }
- private:
- Deque deque; //雙端隊列
- };
- //隊列
- class Queue: public Sequence
- {
- public:
- void push(int x) { deque.push_back(x); }
- void pop() { deque.pop_front(); }
- private:
- Deque deque; //雙端隊列
- };
使用方式如下:
- int main()
- {
- Sequence *s1 = new Stack();
- Sequence *s2 = new Queue();
- s1->push(1); s1->pop();
- s2->push(1); s2->pop();
- delete s1; delete s2;
- return 0;
- }
- int main()
- {
- Sequence *s1 = new Stack();
- Sequence *s2 = new Queue();
- s1->push(1); s1->pop();
- s2->push(1); s2->pop();
- delete s1; delete s2;
- return 0;
- }
本人享有博客文章的版權,轉載請標明出處 http://blog.csdn.net/wuzhekai1985