适配器模式

Posted 2021-02-01 linbq1911

1.定义：将一个类的接口转换成客户期望的另一个接口；使原本接口不兼容的类可以一起工作。

2.类型：结构型

3.适用场景：已经存在的类，它的方法和需求不匹配时(方法结果相同或相似)；
　　　　　   不是软件设计阶段考虑的设计模式，是随着软件维护，由于不同产品、
　　　　　   不同厂家造成功能类似而接口不相同情况下的解决方案。

4.优点：能提高类的透明性和复用，现有的类复用但不需要改变；
　　　   目标类和适配器类解耦，提高程序扩展性；符合开闭原则。

5.缺点：适配器编写过程需要全面考虑，可能会增加系统的复用性；增加系统代码可读的难度。

6.扩展：对象适配器、类适配器。

7.相关设计模式：外观模式

8.实例目录package

9.实例UML类图

10.代码

1 package com.geely.design.pattern.structural.adapter;
2 
3 public class AC220 {
4     public int outputACC220V(){
5         int output = 220;
6         System.out.println("输出交流电" + output + "V");
7         return output;
8     }
9 }

1 package com.geely.design.pattern.structural.adapter;
2 
3 public interface DC5 {
4     int outputDC5V();
5 }

 1 package com.geely.design.pattern.structural.adapter;
 2 
 3 public class PowerAdapter implements DC5{
 4     private AC220 ac220 = new AC220();
 5     @Override
 6     public int outputDC5V() {
 7         int adapterInput = ac220.outputACC220V();
 8         int adapterOutput = adapterInput / 44;
 9         System.out.println("使用PowerAdapter输入AC: " + adapterInput + "V" + "输出DC: " + adapterOutput + "V");
10         return adapterOutput;
11     }
12 }

1 package com.geely.design.pattern.structural.adapter;
2 
3 public class Test {
4     public static void main(String[] args) {
5         DC5 dc5 = new PowerAdapter();
6         dc5.outputDC5V();
7     }
8 }

类适配器

1 package com.geely.design.pattern.structural.adapter.classadapter;
2 
3 public class Adaptee {
4     public void adapterRequest(){
5         System.out.println("被适配者的方法");
6     }
7 }

1 package com.geely.design.pattern.structural.adapter.classadapter;
2 
3 public interface Target {
4     void request();
5 }

package com.geely.design.pattern.structural.adapter.classadapter;

public class Adapter extends Adaptee implements Target {

    @Override
    public void request() {
        super.adapterRequest();
    }
}

1 package com.geely.design.pattern.structural.adapter.classadapter;
2 
3 public class ConcreteTarget implements Target {
4     @Override
5     public void request() {
6         System.out.println("concreateTarget目标方法");
7     }
8 }

 1 package com.geely.design.pattern.structural.adapter.classadapter;
 2 
 3 public class Test {
 4     public static void main(String[] args) {
 5         Target target = new ConcreteTarget();
 6         target.request();
 7 
 8         Target adapterTarget = new Adapter();
 9         adapterTarget.request();
10     }
11 }

对象适配器

package com.geely.design.pattern.structural.adapter.objectadapter;

public class Adaptee {
    public void adapterRequest(){
        System.out.println("被适配者的方法");
    }
}

1 package com.geely.design.pattern.structural.adapter.objectadapter;
2 
3 public interface Target {
4     void request();
5 }

1 package com.geely.design.pattern.structural.adapter.objectadapter;
2 
3 public class Adapter implements Target {
4     private Adaptee adaptee = new Adaptee();
5     @Override
6     public void request() {
7         adaptee.adapterRequest();
8     }
9 }

1 package com.geely.design.pattern.structural.adapter.objectadapter;
2 
3 public class ConcreteTarget implements Target {
4     @Override
5     public void request() {
6         System.out.println("concreateTarget目标方法");
7     }
8 }

 1 package com.geely.design.pattern.structural.adapter.objectadapter;
 2 
 3 public class Test {
 4     public static void main(String[] args) {
 5         Target target = new ConcreteTarget();
 6         target.request();
 7 
 8         Target adapterTarget = new Adapter();
 9         adapterTarget.request();
10     }
11 }