外观模式-Car(最少知识原则)

偏执的太偏执、 2022-07-12 12:20 75阅读 0赞

package H\_Appearance;

/\*\*  
\* 外观模式：提供一个统一的接口，用来访问子系统中的一群接口。外观定义了一个高层接口，让子系统更容易使用  
\* 简化接口时，依然将系统完整的功能暴露出来，供给需要的人用。将客户从组件的子系统中解耦  
\* 如果变得复杂，有太多的朋友牵涉其中，可以增加更多的外观，将子系统分成几个层次  
\* 设计原则：最少知识原则，只和你的密友谈话(减少对象之间交互，只留下几个”密友”)  
\* 要求：在该对象的方法内，只应该调用属于如下范围的方法  
\* 如果某对象是调用其他方法返回结果，不要调用该对象的方法  
\* 1：该对象本身  
\* 2：被当做方法的参数所传递的对象  
\* 3：此方法所创建或实例化的任何对象  
\* 4：对象的任何组件(被实例引用的任何对象，想象成has-a关系)  
\* 缺点：导致更多包装类被制造出来，已处理和其他组件的沟通  
\*  
\*  
\*/  
public class Main \{  
public static void main(String\[\] args) \{  
Amplifier amp = new Amplifier();  
Tuner tuner = new Tuner();  
DvdPlayer dvd = new DvdPlayer();  
CdPlayer cd = new CdPlayer();  
Projector projector = new Projector();  
TheaterLights lights = new TheaterLights();  
Screen screen = new Screen();  
PopcornPopper popper = new PopcornPopper();

HomeTheaterFacade homeTheaterFacade = new HomeTheaterFacade(amp, tuner,
                dvd, cd, projector, lights, screen, popper);
        homeTheaterFacade.watchMovie("看电影");
        homeTheaterFacade.endMovie();
    
    }

\}  
package H\_Appearance;

import java.util.ArrayList;

/\*\*  
\* 遵守最少知识原则，案例  
\*/  
public class Car \{  
Engine engine;

public void start(Key key) {
        Doors doors = new Doors();
        boolean authorized = key.turns();// 被当做参数传递进来的对象，其方法可以被调用
        if (authorized) {
            engine.start();// 调用组件方法
            updateDashboardDisplay();// 调用同一个对象内的本地方法
            doors.lock();// 调用所创建或实例化的对象的方法
        }
        // 这样不行，没有遵守最小知识原则，因为在此调用的方法属于另一次调用的返回对象
        // key.getObject().size();
        // 但是可以再key里面添加一个显示size()结果的方法，这样可以减少所依赖的类的数目
        int size = key.getSize();
    }
    
    private void updateDashboardDisplay() {
    
    }

class Engine \{  
public void start() \{  
\}  
\}

class Doors \{  
public void lock() \{  
\}  
\}

class Key \{  
public boolean turns() \{  
return false;  
\}

public ArrayList getObject() {
        return new ArrayList();
    }
    
    public int getSize() {
        return new ArrayList().size();
    }

\}  
package H\_Appearance;

class Amplifier \{

public void on() {
        // TODO Auto-generated method stub
    
    }
    
    public void setDvd(DvdPlayer dvd) {
        // TODO Auto-generated method stub
    
    }
    
    public void setSurroundSound() {
        // TODO Auto-generated method stub
    
    }
    
    public void setVolume(int i) {
        // TODO Auto-generated method stub
    
    }
    
    public void off() {
        // TODO Auto-generated method stub
    
    }

class Tuner \{

class DvdPlayer \{

public void play(String movie) {
        // TODO Auto-generated method stub
    
    }
    
    public void on() {
        // TODO Auto-generated method stub
    
    }
    
    public void sto() {
        // TODO Auto-generated method stub
    
    }
    
    public void eject() {
        // TODO Auto-generated method stub
    
    }
    
    public void off() {
        // TODO Auto-generated method stub
    
    }

class CdPlayer \{

class Projector \{

public void on() {
        // TODO Auto-generated method stub
    
    }
    
    public void wideScreenMode() {
        // TODO Auto-generated method stub
    
    }
    
    public void off() {
        // TODO Auto-generated method stub
    
    }

class TheaterLights \{

public void dim(int i) {
        // TODO Auto-generated method stub
    
    }
    
    public void on(int i) {
        // TODO Auto-generated method stub
    
    }

class Screen \{

public void down() {
        // TODO Auto-generated method stub
    
    }
    
    public void up() {
        // TODO Auto-generated method stub
    
    }

class PopcornPopper \{

public void on() {
        // TODO Auto-generated method stub
    
    }
    
    public void pop() {
        // TODO Auto-generated method stub
    
    }
    
    public void off() {
        // TODO Auto-generated method stub
    
    }

public class HomeTheaterFacade \{  
// 组合  
Amplifier amp;  
Tuner tuner;  
DvdPlayer dvd;  
CdPlayer cd;  
Projector projector;  
TheaterLights lights;  
Screen screen;  
PopcornPopper popper;

public HomeTheaterFacade(Amplifier amp, Tuner tuner, DvdPlayer dvd,
            CdPlayer cd, Projector projector, TheaterLights lights,
            Screen screen, PopcornPopper popper) {
        this.amp = amp;
        this.tuner = tuner;
        this.dvd = dvd;
        this.cd = cd;
        this.projector = projector;
        this.lights = lights;
        this.screen = screen;
        this.popper = popper;
    }
    
    public void watchMovie(String movie) {
        popper.on();
        popper.pop();
        lights.dim(10);
        screen.down();
        projector.on();
        projector.wideScreenMode();
        amp.on();
        amp.setDvd(dvd);
        amp.setSurroundSound();
        amp.setVolume(5);
        dvd.on();
        dvd.play(movie);
    }
    
    public void endMovie() {
        popper.off();
        lights.on(10);
        screen.up();
        projector.off();
        amp.off();
        dvd.sto();
        dvd.eject();
        dvd.off();
    }