适配器模式

//被适配的类
public class Voltage220V {
    //输出220V的电压，不变
    public int output220V() {
        int src = 220;
        System.out.println("电压=" + src + "伏");
        return src;
    }
}

//适配接口
public interface IVoltage5V {
    public int output5V();
}

//适配器类
public class VoltageAdapter  implements IVoltage5V {

    private Voltage220V voltage220V; // 关联关系-聚合
    
    //通过构造器，传入一个 Voltage220V 实例
    public VoltageAdapter(Voltage220V voltage220v) {
        
        this.voltage220V = voltage220v;
    }

    @Override
    public int output5V() {
        
        int dst = 0;
        if(null != voltage220V) {
            int src = voltage220V.output220V();//获取220V 电压
            System.out.println("使用对象适配器，进行适配~~");
            dst = src / 44;
            System.out.println("适配完成，输出的电压为=" + dst);
        }
        return dst;
        
    }
}

public class Phone {
    //充电
    public void charging(IVoltage5V iVoltage5V) {
        if(iVoltage5V.output5V() == 5) {
            System.out.println("电压为5V, 可以充电~~");
        } else if (iVoltage5V.output5V() > 5) {
            System.out.println("电压大于5V, 不能充电~~");
        }
    }
}

public class Client {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        System.out.println(" === 对象适配器模式 ====");
        Phone phone = new Phone();
        phone.charging(new VoltageAdapter(new Voltage220V()));
    }
}

public interface Interface4 {
    public void m1();
    public void m2();
    public void m3();
    public void m4();
}

//在AbsAdapter 我们将 Interface4 的方法进行默认实现
public abstract class AbsAdapter implements Interface4 {

    //默认实现
    public void m1() {

    }

    public void m2() {

    }

    public void m3() {

    }

    public void m4() {

    }
}

public class Client {
    public static void main(String[] args) {
        
        AbsAdapter absAdapter = new AbsAdapter() {
            //只需要去覆盖我们 需要使用 接口方法
            @Override
            public void m1() {
                // TODO Auto-generated method stub
                System.out.println("使用了m1的方法");
            }
        };
        
        absAdapter.m1();
    }
}

//多种Controller实现  
public interface Controller {

}

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

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

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

///定义一个Adapter接口 
public interface HandlerAdapter {
    public boolean supports(Object handler);

    public void handle(Object handler);
}

// 多种适配器类

class SimpleHandlerAdapter implements HandlerAdapter {

    public void handle(Object handler) {
        ((SimpleController) handler).doSimplerHandler();
    }

    public boolean supports(Object handler) {
        return (handler instanceof SimpleController);
    }

}

class HttpHandlerAdapter implements HandlerAdapter {

    public void handle(Object handler) {
        ((HttpController) handler).doHttpHandler();
    }

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

}

class AnnotationHandlerAdapter implements HandlerAdapter {

    public void handle(Object handler) {
        ((AnnotationController) handler).doAnnotationHandler();
    }

    public boolean supports(Object handler) {

        return (handler instanceof AnnotationController);
    }

}

import java.util.ArrayList;
import java.util.List;

public class DispatchServlet {

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

    public DispatchServlet() {
        handlerAdapters.add(new AnnotationHandlerAdapter());
        handlerAdapters.add(new HttpHandlerAdapter());
        handlerAdapters.add(new SimpleHandlerAdapter());
    }

    public void doDispatch() {

        // 此处模拟SpringMVC从request取handler的对象，
        // 适配器可以获取到希望的Controller
         HttpController controller = new HttpController();
        // AnnotationController controller = new AnnotationController();
        //SimpleController controller = new SimpleController();
        // 得到对应适配器
        HandlerAdapter adapter = getHandler(controller);
        // 通过适配器执行对应的controller对应方法
        adapter.handle(controller);

    }

    public HandlerAdapter getHandler(Controller controller) {
        //遍历：根据得到的controller(handler), 返回对应适配器
        for (HandlerAdapter adapter : this.handlerAdapters) {
            if (adapter.supports(controller)) {
                return adapter;
            }
        }
        return null;
    }

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

}