2.结构性模式
2.2 BRIDGE模式
别名：handle/body
这个模式体现了组合相对于继承的优势。
2.2.1动机
当一个抽象可能有多个实现时，通常用继承来协调它们。抽象类定义对该抽象的接口，而具体的子类则用不同方式加以实现。但是此方法有时不够灵活。继承机制将抽象部分与它的实现部分固定在一起，使得难以对抽象部分和实现部分独立地进行修改、扩充和重用。而组合方式可以使得通过抽象部分与实现部分进行独立的修改。
2.2.2结构
Client
― Bridge模式的使用者
Abstraction
― 定义抽象类的接口。
― 维护一个指向Im p l e m e n t o r 类型对象的指针。< http://www.2cto.com/kf/ware/vc/" target="_blank" class="keylink">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"Abstraction.h"
#include"AbstractionImp.h"
#include
using namespace std;
Abstraction::Abstraction()
{
}
Abstraction::~Abstraction()
{
}
RefinedAbstraction::RefinedAbstraction(Abstra
ctionImp* imp)
{
_imp = imp;
}
RefinedAbstraction::~RefinedAbstraction()
{
}
void RefinedAbstraction::Operation()
{
_imp->Operation();
}
代码片断3：AbstractionImp.h
//AbstractionImp.h
#ifndef _ABSTRACTIONIMP_H_
#define _ABSTRACTIONIMP_H_
class AbstractionImp
{
public:
virtual ~AbstractionImp();
virtual voidOperation() = 0;
protected:
AbstractionImp();
private:
};
class ConcreteAbstractionImpA :public
AbstractionImp
{
public:
ConcreteAbstractionImpA();
~ConcreteAbstractionImpA();
virtual voidOperation();
protected:
private:
};
class ConcreteAbstractionImpB :public
AbstractionImp
{
public:
ConcreteAbstractionImpB();
~ConcreteAbstractionImpB();
virtual voidOperation();
protected:
private:
};
#endif //~_ABSTRACTIONIMP_H_
代码片断4：AbstractionImp.cpp
//AbstractionImp.cpp
#include"AbstractionImp.h"
#include
using namespace std;
AbstractionImp::AbstractionImp()
{
}
AbstractionImp::~AbstractionImp()
{
}
void AbstractionImp::Operation()
{
cout << "AbstractionImp....imp..." << endl;
}
ConcreteAbstractionImpA::ConcreteAbstractio
nImpA()
{
}
ConcreteAbstractionImpA::~ConcreteAbstracti
onImpA()
{
}
void ConcreteAbstractionImpA::Operation()
{
cout << "ConcreteAbstractionImpA...." << e
ndl;
}
ConcreteAbstractionImpB::ConcreteAbstractio
nImpB()
{
}
ConcreteAbstractionImpB::~ConcreteAbstracti
onImpB()
{
}
void ConcreteAbstractionImpB::Operation()
{
cout << "ConcreteAbstractionImpB...." << e
ndl;
}
代码片断5：main.cpp
//main.cpp
#include"Abstraction.h"
#include"AbstractionImp.h"
#include
using namespace std;
int main(int argc, char*argv[])
{
AbstractionImp*imp = new
ConcreteAbstractionImpA();
Abstraction*abs = new
RefinedAbstraction(imp);
abs->Operation();
return 0;
}
2.2.5 例子-JAVA
Implementor类：
1. package com.qianyan.bridge;
2.
3. public interface Engine {
4.
5. /**
6. * 安装发动引擎
7. */
8. public void installEngine();
9. }
ConcreteImplementor类：
1. package com.qianyan.bridge;
2.
3. public class Engine2000 implements Engine {
4.
5. @Override
6. public void installEngine() {
7. System.out.println("安装2000CC发动引擎");
8. }
9.
10.}
1. package com.qianyan.bridge;
2.
3. public class Engine2200 implements Engine {
4.
5. @Override
6. public void installEngine() {
7. System.out.println("安装2200CC发动引擎");
8. }
9.
10.}
Abstraction类：
1. package com.qianyan.bridge;
2.
3. public abstract class Vehicle {
4.
5. private Engine engine;
6.
7. public Vehicle(Engine engine) {
8. this.engine = engine;
9. }
10.
11. public Engine getEngine() {
12. return engine;
13. }
14.
15. public void setEngine(Engine engine) {
16. this.engine = engine;
17. }
18.
19. public abstract void installEngine();
20.}
Refined Abstraction类：
1. package com.qianyan.bridge;
2.
3. public class Bus extends Vehicle {
4.
5. public Bus(Engine engine) {
6. super(engine);
7. }
8.
9. @Override
10. public void installEngine() {
11. System.out.print("Bus:");
12. this.getEngine().installEngine();
13. }
14.
15.}
1. package com.qianyan.bridge;
2.
3. public class Jeep extends Vehicle {
4.
5. public Jeep(Engine engine) {
6. super(engine);
7. }
8. @Override
9. public void installEngine() {
10. System.out.print("Jeep:");
11. this.getEngine().installEngine();
12. }
13.
14.}
1. package com.qianyan.bridge;
2.
3. public class MainClass {
4. public static void main(String[] args) {
5. Engine engine2000 = new Engine2000();
6. Engine engine2200 = new Engine2200();
7.
8. Vehicle bus = new Bus(engine2000);
9. bus.installEngine();
10.
11. Vehicle jeep = new Jeep(engine2200);
12. jeep.installEngine();
13. }
14.}
Result：
1. Bus:安装2000CC发动引擎
Jeep:安装2200CC发动引擎