Java设计模式之七大设计原则

/**
 * 视频用户接口
 */
public interface IVideoUserService {

    void definition();

    void advertisement();
}

/**
 * 访客用户
 */
public class GuestVideoUserService implements IVideoUserService {

    public void definition() {
        System.out.println("访客用户，视频480P高清");
    }

    public void advertisement() {
        System.out.println("访客用户，视频有广告");
    }

}

/**
 * 普通用户
 */
public class OrdinaryVideoUserService implements IVideoUserService {

    public void definition() {
        System.out.println("普通用户，视频720P超清");
    }

    public void advertisement() {
        System.out.println("普通用户，视频有广告");
    }
}

/**
 * VIP用户
 */
public class VipVideoUserService implements IVideoUserService {

    public void definition() {
        System.out.println("VIP用户，视频1080P蓝光");
    }

    public void advertisement() {
        System.out.println("VIP会员，视频无广告");
    }
}

public class Client {

    public static void main(String[] args) {
        // 访客用户
        GuestVideoUserService guest = new GuestVideoUserService();
        guest.definition();
        guest.advertisement();

        // 普通用户
        OrdinaryVideoUserService ordinary = new OrdinaryVideoUserService();
        ordinary.definition();
        ordinary.advertisement();

        //VIP用户
        VipVideoUserService vip = new VipVideoUserService();
        vip.definition();
        vip.advertisement();

    }

}

/**
 * 面积计算实现
 */
public class CalculationArea implements ICalculationArea {

    private final static double π = 3.14D;

    public double rectangle(double x, double y) {
        return x * y;
    }

    public double triangle(double x, double y, double z) {
        double p = (x + y + z) / 2;
        return Math.sqrt(p * (p - x) * (p - y) * (p - z));
    }

    public double circular(double r) {
        return π * r * r;
    }

}

/**
 * 扩展继承，实现自己的需求
 */
public class CalculationAreaExt extends CalculationArea {

    private final static double π = 3.141592653D;

    @Override
    public double circular(double r) {
        return π * r * r;
    }

}

/**
 *  面积计算接口
 */
public interface ICalculationArea {

    /**
     * 计算面积，长方形
     *
     * @param x 长
     * @param y 宽
     * @return 面积
     */
    double rectangle(double x, double y);

    /**
     * 计算面积，三角形
     * @param x 边长x
     * @param y 边长y
     * @param z 边长z
     * @return  面积
     *
     * 海伦公式：S=√[p(p-a)(p-b)(p-c)] 其中：p=(a+b+c)/2
     */
    double triangle(double x, double y, double z);

    /**
     * 计算面积，圆形
     * @param r 半径
     * @return 面积
     *
     * 圆面积公式：S=πr²
     */
    double circular(double r);

}

public class Client {

    public static void main(String[] args) {
        CalculationAreaExt calculationAreaExt = new CalculationAreaExt();
        double res = calculationAreaExt.circular(10);
        System.out.println(res);
    }
}