Java大数据平台开发 学习笔记（36）—— java设计模式（适配器模式）知识汇总

一、前言：

主要分为三类：类适配器模式、对象的适配器模式、接口的适配器模式。

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二、类适配器模式：

2.1、UML图：

2.2、代码实现：

Step 1) 创建 Phone 类：

public class Phone {
    
    
    public void charging(Voltage5V voltage5V){
    
    
        if(voltage5V.output5V() == 5){
    
    
            System.out.println("电压为 5V 可以充电 ！");
        }else if(voltage5V.output5V() > 5) {
    
    
            System.out.println("电压大于 5V 不能充电 ！");
        }
    }
}

Step 2) 创建 Voltage5V 接口：

public interface Voltage5V {
    
    
    public int output5V();
}

Step 3) 创建 Voltage220V 类：

public class Voltage220V {
    
    
    public int output220V(){
    
    
        int src = 220;
        System.out.println("电压为：" + src + "伏");
        return src;
    }
}

Step 4) 创建 VoltageAdapter 类：

public class VoltageAdapter extends Voltage220V implements Voltage5V{
    
    
    @Override
    public int output5V() {
    
    
        int srcV = output220V();
        int dstV = srcV/44;
        return dstV;
    }
}

Step 5) 创建 main 方法：

public class Client {
    
    
    public static void main(String[] args) {
    
    
        System.out.println("== 类适配器 ===");
        Phone phone = new Phone();
        phone.charging(new VoltageAdapter());
    }
}

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三、对象适配器模式：

3.1、UML图：

3.2、代码实现：

Step 1) 创建 Phone 类：

public class Phone {
    
    
    public void charging(Voltage5V voltage5V){
    
    
        if(voltage5V.output5V() == 5){
    
    
            System.out.println("电压为 5V 可以充电 ！");
        }else if(voltage5V.output5V() > 5) {
    
    
            System.out.println("电压大于 5V 不能充电 ！");
        }
    }
}

Step 2) 创建 Voltage5V 接口：

public interface Voltage5V {
    
    
    public int output5V();
}

Step 3) 创建 Voltage220V 类：

public class Voltage220V {
    
    
    public int output220V(){
    
    
        int src = 220;
        System.out.println("电压为：" + src + "伏");
        return src;
    }
}

Step 4) 创建 VoltageAdapter 类：

public class VoltageAdapter implements Voltage5V {
    
    

    private Voltage220V voltage220V;

    public VoltageAdapter(Voltage220V voltage220V){
    
    
        this.voltage220V = voltage220V;
    }

    @Override
    public int output5V() {
    
    
        int dst = 0;
        if(null != voltage220V){
    
    
            int src = voltage220V.output220V();
            System.out.println("使用对象适配器，进行适配！");
            dst = src / 44;
            System.out.println("适配器完成！");
        }
        return dst;
    }
}

Step 5) 创建 main 方法：

public class Client {
    
    
    public static void main(String[] args) {
    
    
        System.out.println("== 对象适配器 ===");
        Phone phone = new Phone();
        phone.charging(new VoltageAdapter(new Voltage220V()));
    }
}

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四、接口适配器模式：

4.1、UML图：

4.2、代码实现：

Step 1) 创建 Controller 接口、及其 HttpController、SimleController、AnnotationController 实现类：

public interface Controller {
    
    
}

class HttpController implements Controller {
    
    
    public void doHttpHandler() {
    
    
        System.out.println("http...");
    }
}

class SimleController implements Controller {
    
    
    public void doSimplerHandler() {
    
    
        System.out.println("simple...");
    }
}

class AnnotationController implements Controller {
    
    
    public void doAnnotationController() {
    
    
        System.out.println("annotation");
    }
}

Step 2) 创建 HandlerAdapter 接口、及其 SimpleHanderAdaper、HttpHandlerAdaper、AnnotationHandlerAdaper 实现类：

public interface HandlerAdapter {
    
    
    public boolean supports(Object handler);
    public void handle(Object hander);
}

class SimpleHanderAdaper implements HandlerAdapter{
    
    

    @Override
    public boolean supports(Object handler) {
    
    
        return (handler instanceof SimleController);
    }

    @Override
    public void handle(Object hander) {
    
    
        ((SimleController) hander).doSimplerHandler();
    }
}

class HttpHandlerAdaper implements HandlerAdapter{
    
    

    @Override
    public boolean supports(Object handler) {
    
    
        return (handler instanceof HttpController);
    }

    @Override
    public void handle(Object hander) {
    
    
        ((HttpController) hander).doHttpHandler();
    }
}

class AnnotationHandlerAdaper implements HandlerAdapter{
    
    

    @Override
    public boolean supports(Object handler) {
    
    
        return (handler instanceof AnnotationController);
    }

    @Override
    public void handle(Object hander) {
    
    
        ((AnnotationController) hander).doAnnotationController();;
    }
}

Step 3) 创建 DispatchServlet 类、且与 main 方法：

public class DispatchServlet {
    
    
    public static List<HandlerAdapter> handlerAdapters  = new ArrayList<>();

    public DispatchServlet(){
    
    
        handlerAdapters.add(new AnnotationHandlerAdaper());
        handlerAdapters.add(new HttpHandlerAdaper());
        handlerAdapters.add(new SimpleHanderAdaper());
    }

    public void doDisptch(){
    
    
        SimleController controller = new SimleController();
//        HttpController controller = new HttpController();
//        AnnotationController controller = new AnnotationController();
        HandlerAdapter adapter = getHandler(controller);
        adapter.handle(controller);
    }

    public HandlerAdapter getHandler(Controller controller){
    
    
        for(HandlerAdapter adapter : this.handlerAdapters){
    
    
            if(adapter.supports(controller)){
    
    
                return adapter;
            }
        }
        return null;
    }

    public static void main(String[] args) {
    
    
        new DispatchServlet().doDisptch();
    }
}

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• 由 ChiKong_Tam 写于 2020 年 10 月 18 日