/**

  * 测试类,包含一个主方法;

  * 调用求体积方法输出;

  */

 package cn.edu.ccut.object3;

 import java.util.Scanner;

 public class Test {

     public static void main(String[] args) {

         char c;

         while(true){

             System.out.println("请输入柱体底的形状('j'矩形、's'三角形、'z'正方形、't'梯形、'y'圆形、'F'结束程序):");

             Scanner reader = new Scanner(System.in);

             c = reader.next().charAt(0); //c接受字符型输入;

             if(c == 'F'){     //退出程序标志;

                 System.out.println("程序结束！");

                 break;

             }

             factory f = new factory();

             Cone cone = new Cone(f.ctrl_di(c) , 5); //定义矩形对象,根据用户输出控制底,高为5;

             System.out.println("柱体体积是:"+cone.getV());

         }

     }

 }

 /**

  * 工厂类,实现简单工厂模式,包含一个方法;

  * ctrl_di实现了根据用户输入换底;

  */

 package cn.edu.ccut.object3;

 public class factory {

     Shape shape = null;

     public Shape ctrl_di(char c){ //实现了根据用户输入换底;

         switch(c){

         case 'j':shape = new Rec(3,4);break;

         case 's':shape = new Triangle(3,4,5);break;

         case 'z':shape = new Zheng(2);break;

         case 't':shape = new Trapezoid(4,6,7);break;

         case 'y':shape = new Circle(3);break;

         default:System.out.println("error");

         }

         return shape;

     }

 }

 /**

  * 图形接口;

  * 定义了一个计算面积的抽象方法getArea;

  */

 package cn.edu.ccut.object3;

 public interface  Shape {

     public double getArea(); //抽象方法计算面积;

 }

 /**

  * 矩形类,使用了图形接口,包含两个成员变量一个构造方法,并重写了getArea方法;

  * 两个成员变量分别代表举行的长和宽;

  * 构造方法初始化,getArea计算面积;

  */

 package cn.edu.ccut.object3;

 public class Rec implements Shape {

     double a;

     double b;

     Rec(double a , double b){

         this.a = a;

         this.b = b;

     }

     public double getArea(){

         return (a*b);

     }

 }

 /**

  * 正方形类,继承了矩形类，包含两个方法;

  * 构造方法初始化,getArea计算面积

  */

 package cn.edu.ccut.object3;

 public class Zheng extends Rec {

     Zheng(double a){

         super(a, a); //利用super调用父类构造方法;

     }

     public double getArea(){ //方法重写;

         return (a*a);

     }

 }

 /**

  * 圆类,使用了图形接口,包含一个成员变量,两个方法;

  * 成员变量r为半径;

  * 构造方法初始化,重写了getArea方法;

  */

 package cn.edu.ccut.object3;

 public class Circle implements Shape{

     double r;

     public Circle(double r){

         this.r = r;

     }

     public double getArea(){

         return (Math.PI*r*r);

     }

 }

 /**

  * 三角形类,使用了图形接口,包含了三个成员变量,两个方法;

  * 成员变量a,b,c分别代表三角形的三个边;

  * 构造方法初始化,重写了getArea方法;

  */

 package cn.edu.ccut.object3;

 public class Triangle implements Shape{

     double a;

     double b;

     double c;

     public Triangle (double a , double b , double c){

         this.a = a;

         this.b = b;

         this.c = c;

     }

     public double getArea(){

         double p = (a + b + c) / 2;

         return Math.sqrt(p * (p - a) * (p - b) * (p - c));

     }

 }

 /**

  * 梯形类,使用了图形接口,包含三个成员变量,两个方法;

  * 成员变量a,b代表梯形的上底和下底,high代表高;

  * 构造方法,重写getArea;

  */

 package cn.edu.ccut.object3;

 public class Trapezoid implements Shape{

     double a;

     double b;

     double high;

     public Trapezoid(double a , double b , double high){

         this.a = a;

         this.b = b;

         this.high = high;

     }

     public double getArea(){

         return (((a + b) * high) / 2);

     }

 }

 /**

  * 柱体类,两个成员变量,三个方法;

  * 成员变量shape代表底,high代表高;

  * 构造方法初始化,getV计算柱体体积,setDi可用于换底;

  */

 package cn.edu.ccut.object3;

 public class Cone {

     Shape shape;

     double high;

     public Cone(Shape shape , double high){

         this.shape = shape;

         this.high = high;

     }

     public double getV(){

         return (shape.getArea()*high);

     }

     public void setDi(Shape shape){ //利用修改器换底

         this.shape = shape;

     }

 }