面向对象 (5)计算柱体体积可换底

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。

一、源程序

1、Test.java

/**计算棱柱体积可换底
 * 9个类
 */
package w29;

import java.util.Scanner;

public class Test {
    
    public static void main(String[] args) {
        while(true){
            Scanner reader = new Scanner(System.in);
            System.out.println("请输入柱体底的形状:r（矩形）；s（正方形）；t（梯形）；T（三角形）；c（圆形）。");
            char c = reader.next().charAt(0);
            Factory factory = new Factory();
            Shape shape;
            Column column = new Column(factory.getShape(c),reader.nextDouble());
            System.out.println("柱体的体积"+column.getVolume());
        }
    }
}

2、Factory.java

package w29;
//工厂类
import java.util.Scanner;

public class Factory {
    protected Shape getShape(char c){
        Scanner reader = new Scanner(System.in);
        Shape shape = null;
        switch(c){
        case 'r':System.out.println("请输入矩形底的长和宽、柱体的高");shape = new Rectangle(reader.nextDouble(),reader.nextDouble());break;
        case 's':System.out.println("请输入正方形底的边、柱体的高");shape = new Square(reader.nextDouble());break;
        case 't':System.out.println("请输入梯形底的上下底和高、柱体的高");shape = new trapezium(reader.nextDouble(),reader.nextDouble(),reader.nextDouble());break;
        case 'T':System.out.println("请输入三角形底的三边、柱体的高");shape = new Triangle(reader.nextDouble(),reader.nextDouble(),reader.nextDouble());break;
        case 'c':System.out.println("请输入圆形底的半径、柱体的高");shape = new Circle(reader.nextDouble());break;
        }
        return shape;
    }
}

3、Shape.java

package w29;
//形状接口
public interface Shape {
    double getArea();
}

4、Rectangle.java

package w29;
//矩形类
public class Rectangle implements Shape {
    double width,length;
    public Rectangle(double width,double length){
        this.width = width;
        this.length = length;
    }
    public double getArea() {
        return width*length;
    }
}

5、Square.java

package w29;
//正方形类
public class Square extends Rectangle {

    public Square(double side) {
        super(side, side);
    }
    public double getArea() {
        return width*length;
    }
}

6、trapezium.java

package w29;
//梯形类
public class trapezium extends Rectangle {
    double height;
    public trapezium(double up, double down, double height) {
        super(up, down);
        this.height = height;
    }
    public double getArea() {
        return (width+length)*height/2;
    }
}

7、Triangle.java

package w29;
//三角形类
public class Triangle implements Shape {
    double a,b,c;
    public Triangle(double a, double b, double c) {
        super();
        this.a = a;
        this.b = b;
        this.c = c;
    }
    public double getArea() {
        double sum = (a+b+c)/2;
        return Math.sqrt(sum*(sum-a)*(sum-b)*(sum-c));
    }
}

8、Circle.java

package w29;
//圆形类
public class Circle implements Shape {
    double radius;
    public Circle(double radius) {
        super();
        this.radius = radius;
    }
    public double getArea() {
        // TODO Auto-generated method stub
        return radius*radius*3.14;
    }
}

9、Column.java

package w29;
//柱体类
public class Column {
    Shape shape;
    double high;
    public Column(Shape shape, double high) {
        super();
        this.shape = shape;
        this.high = high;
    }
    public double getVolume(){
        return shape.getArea()*high;
    }
}

二、成功界面截图