11.多用组合和少继承

abstract class Shape {
    public abstract void draw();
}

class Circle extends Shape {
    public void draw() {
        System.out.println("Drawing a circle");
    }
}

class Rectangle extends Shape {
    public void draw() {
        System.out.println("Drawing a rectangle");
    }
}

class RedCircle extends Circle {
    public void draw() {
        System.out.println("Drawing a red circle");
    }
}

class BlueCircle extends Circle {
    public void draw() {
        System.out.println("Drawing a blue circle");
    }
}

class RedRectangle extends Rectangle {
    public void draw() {
        System.out.println("Drawing a red rectangle");
    }
}

class BlueRectangle extends Rectangle {
    public void draw() {
        System.out.println("Drawing a blue rectangle");
    }
}

public class Main {
    public static void main(String[] args) {
        Shape redCircle = new RedCircle();
        redCircle.draw();
        
        Shape blueRectangle = new BlueRectangle();
        blueRectangle.draw();
    }
}

// 颜色接口
interface Color {
    void applyColor();
}

class RedColor implements Color {
    public void applyColor() {
        System.out.println("Applying red color");
    }
}

class BlueColor implements Color {
    public void applyColor() {
        System.out.println("Applying blue color");
    }
}

// 形状抽象类
abstract class Shape {
    protected Color color;

    public Shape(Color color) {
        this.color = color;
    }

    abstract void draw();
}

class Circle extends Shape {
    public Circle(Color color) {
        super(color);
    }

    public void draw() {
        System.out.print("Drawing a circle with ");
        color.applyColor();
    }
}

class Rectangle extends Shape {
    public Rectangle(Color color) {
        super(color);
    }

    public void draw() {
        System.out.print("Drawing a rectangle with ");
        color.applyColor();
    }
}

public class Main {
    public static void main(String[] args) {
        Shape redCircle = new Circle(new RedColor());
        redCircle.draw();
        
        Shape blueRectangle = new Rectangle(new BlueColor());
        blueRectangle.draw();
    }
}

public abstract class AbstractBird {
    //...省略其他属性和方法...
    public void fly() {
        //...
    }

    public void eat(){
    }

    public void call(){
    }

    public void swimming(){
    }
}
public class BirdA extends AbstractBird {
    //A ， 不会飞，会叫，会游泳
    //...省略其他属性和方法...
    public void fly() {
        throw new RuntimeException("I can't fly.'");
    }

    @Override
    public void call() {
        super.call();
    }

    @Override
    public void swimming() {
        super.swimming();
    }
}

public class BirdB extends AbstractBird {
    //B， 不会飞，不会叫，会游泳
    //...省略其他属性和方法...
    public void fly() {
        throw new RuntimeException("I can't fly.'");
    }

    @Override
    public void call() {
        throw new RuntimeException("I can't call.'");
    }

    @Override
    public void swimming() {
        super.swimming();
    }
}

public class BirdC extends AbstractBird {
    //C，， 会飞，不会叫，不会游泳
    //...省略其他属性和方法...
    public void fly() {

    }

    @Override
    public void call() {
        super.call();
    }

    @Override
    public void swimming() {
        super.swimming();
    }
}

public interface Flyable {
  void fly();
}
public interface Tweetable {
  void tweet();
}
public interface EggLayable {
  void layEgg();
}
public class Ostrich implements Tweetable, EggLayable {//鸵鸟
  //... 省略其他属性和方法...
  @Override
  public void tweet() { //... }
  @Override
  public void layEgg() { //... }
}
public class Sparrow impelents Flayable, Tweetable, EggLayable {//麻雀
  //... 省略其他属性和方法...
  @Override
  public void fly() { //... }
  @Override
  public void tweet() { //... }
  @Override
  public void layEgg() { //... }
}

public interface Flyable {
  void fly()；
}
public class FlyAbility implements Flyable {
  @Override
  public void fly() { //... }
}
//省略Tweetable/TweetAbility/EggLayable/EggLayAbility
 
public class Ostrich implements Tweetable, EggLayable {//鸵鸟
  private TweetAbility tweetAbility = new TweetAbility(); //组合
  private EggLayAbility eggLayAbility = new EggLayAbility(); //组合
  //... 省略其他属性和方法...
  @Override
  public void tweet() {
    tweetAbility.tweet(); // 委托
  }
  @Override
  public void layEgg() {
    eggLayAbility.layEgg(); // 委托
  }
}

public class Url {
  //...省略属性和方法
}
 
public class Crawler {
  private Url url; // 组合
  public Crawler() {
    this.url = new Url();
  }
  //...
}
 
public class PageAnalyzer {
  private Url url; // 组合
  public PageAnalyzer() {
    this.url = new Url();
  }
  //..
}

public class FeignClient { // feign client框架代码
  //...省略其他代码...
  public void encode(String url) { //... }
}
 
public void demofunction(FeignClient feignClient) {
  //...
  feignClient.encode(url);
  //...
}
 
public class CustomizedFeignClient extends FeignClient {
  @Override
  public void encode(String url) { //...重写encode的实现...}
}
 
// 调用
FeignClient client = new CustomizedFeignClient();
demofunction(client);