第九次作业----接口回调

一、题目

利用接口和接口回调，实现简单工厂模式，当输入不同的字符，

代表相应图形时，利用工厂类获得图形对象，再计算以该图形为底的柱体体积。

二、代码段

（1）shape类

package zcy;

public interface Shape {
    public double getArea();//定义接口求面积方法

}

（2）Rectangle类

package zcy;
//定义矩形类，调用shape接口
public class Rectangle implements Shape{
    public double length;
    public double width;
    public Rectangle(double length,double width){
        this.length=length;
        this.width=width;
    }
    public double getArea(){
        return width*length;
    }

}

（3）Triangle类

package zcy;
//定义三角形类调用Shape接口
public class Triangle implements Shape{
    double a,b,c;
    public Triangle(double a,double b,double c){
        this.a=a;
        this.b=b;
        this.c=c;
    }

    public double getArea() {
        double m=(a+b+c)/2;
        return Math.sqrt(m*(m-a)*(m-b)*(m-c));
    }

（4）TiXing类

package zcy;
//定义梯形类，调用shape接口
public class TiXing implements Shape {
    double a;
    double b;
    double h;
    public TiXing(double a,double b,double h){
        this.a=a;
        this.b=b;
        this.h=h;
    }
    public double getArea(){
        return (a+b)*h/2;
    }

}

（5）Square类

package zcy;
//定义正方形类继承矩形类
public class Square implements Shape{
    double a;
    public Square(double a){
        this.a=a;
    }
    public double getArea(){
        return a*a;
    }

}

（6）Circle类

package zcy;
//定义圆形类，调用shape接口
public class Circle implements Shape{
    double r;
    public Circle(double r){
        this.r=r;
    }
    public double getArea(){
        return 3.14*r*r;
    }

}

（7）Column类

package zcy;
//定义柱体类，柱体高，换底方法
public class Column {
    Shape shape;
    double height;
    public Column(Shape shape,double height){
        this.shape=shape;
        this.height=height;
    }
    public double getVolumn(){
        return shape.getArea()*height;
    }
    public void changeShape(Shape shape){
        this.shape=shape;
    }

}

（8）Factory类

package zcy;

import java.util.Scanner;

//工厂类 实现通过输入字符，自动创建对应类型的对象
public class Factory {
    Shape shape=null;
    Scanner reader = new Scanner(System.in);
    public Shape getShape() {
        char i=reader.next().charAt(0);
            switch(i) {
            case'y':System.out.println("以圆形为底的柱体体积是：");shape=new Circle(5);break;
            case'z':System.out.println("以正方形为底的柱体体积是：");shape=new Square(6);break;
            case't':System.out.println("以梯形为底的柱体体积是：");shape=new TiXing(4,5,2);break;
            case'j':System.out.println("以矩形为底的柱体体积是：");shape=new Rectangle(4,5);break;
            case's':System.out.println("以三角形为底的柱体体积是：");shape=new Triangle(4,5,6);break;
            }
            return shape;
    }
}
    
    

（9）Test类

package zcy;

import java.util.Scanner;

public class Test {

    /**
     * @param args
     */
    public static void main(String[] args) {
                System.out.println("请输入柱体的高：");
                double h;
                Scanner r=new Scanner(System.in);
                h=r.nextDouble();
                 for(int j=0;j<5;j++){
                System.out.println("请选择柱体以何图形为底：“y”为圆形，“z”为正方形，“t”为梯形，“j”为矩形“s”为三角形");
                Factory f=new Factory();
                Column col=new Column(f.getShape(),h);
                col.changeShape(f.shape);
                System.out.println(col.getVolumn());
        }
        }


}

三、结果运行图