多态练习：
- 一、设计一个绘图系统:支持画矩形，圆，等边三角形。
功能：计算周长，面积，画图
package org.mobiletrain;
import java.awt.Color;
import java.awt.Graphics;
/**
* 图形(抽象类)
* @author apple
*
*/
public abstract class Shape{
protected Color color;
protected int centerX;
protected int centerY;
/**
* 构造器
* @param centerX 中心点的横坐标
* @param centerY 中心点的纵坐标
* @param color 画笔颜色
*/
public Shape(int centerX,int centerY,Color color) {
this.centerX = centerX;
this.centerY = centerY;
this.color = color;
}
/**
* 计算周长
* @return 图形的周长
*/
public abstract double perimeter();
/**
* 计算面积
* @return 图形的面积
*/
public abstract double area();
/**
* 绘图
* @param g 画笔(绘图的上下文环境)
*/
public void draw(Graphics g){
g.setColor(color);
g.drawString(String.format("周长：%.2f", perimeter()), centerX, centerY);
g.drawString(String.format("面积：%.2f", area()), centerX, centerY + 20);
}
}
package org.mobiletrain;
import java.awt.Color;
import java.awt.Graphics;
/**
* 矩形
* @author apple
*
*/
public class Rectangle extends Shape{
protected int height;
protected int width;
public Rectangle(int centerX,int centerY,Color color,int width,int height) {
super(centerX, centerY, color);
this.width = width;
this.height = height;
}
@Override
public double perimeter() {
return (height + width) * 2;
}
@Override
public double area() {
return height * width;
}
@Override
public void draw(Graphics g) {
super.draw(g);
g.drawRect(centerX - width / 2 - 40, centerY - height / 2 - 40, width, height);
}
}
package org.mobiletrain;
import java.awt.Color;
import java.awt.Graphics;
/**
* 圆
*/
public class Circle extends Shape{
private int radius;
public Circle(int centerX,int centerY,Color color,int radius) {
super(centerX, centerY, color);
this.radius = radius;
}
@Override
public double perimeter() {
return 2 * Math.PI * radius;
}
@Override
public double area() {
return Math.PI * radius * radius;
}
@Override
public void draw(Graphics g) {
super.draw(g);
g.drawOval(centerX - radius, centerY - radius, 2 * radius, 2 * radius);
}
}
package org.mobiletrain;
import java.awt.Color;
import java.awt.Graphics;
public class Triangle extends Shape{
private int length;
public Triangle(int centerX,int centerY,Color color,int length) {
super(centerX, centerY, color);
this.length = length;
}
@Override
public double perimeter() {
return length * 3;
}
@Override
public double area() {
return Math.sqrt(perimeter() / 2 * (perimeter() - length) *
(perimeter() - length) * (perimeter() - length));
}
@Override
public void draw(Graphics g) {
super.draw(g);
int x1 = centerX;
int y1 = (int) (centerY - length / 2 / Math.cos(Math.PI / 6));
int x2 = centerX - length / 2;
int y2 = (int) (centerY + Math.tan(Math.PI / 6) * length / 2);
int x3 = centerX + length / 2;
int y3 = y2;
g.setColor(color);
g.drawLine(x1, y1, x2, y2);
g.drawLine(x2, y2, x3, y3);
g.drawLine(x3, y3, x1, y1);
}
}
package org.mobiletrain.ui;
import java.awt.Color;
import java.awt.Graphics;
import javax.swing.JFrame;
import org.mobiletrain.Circle;
import org.mobiletrain.Rectangle;
import org.mobiletrain.Triangle;;
@SuppressWarnings("serial")
public class ShapeFrame extends JFrame {
private Circle circle = new Circle(600, 300, Color.green, 100);
private Rectangle rectangle = new Rectangle(300, 450, Color.red, 300, 200);
private Triangle triangle = new Triangle(300, 200, Color.blue, 200);
/**
* 构造器，设置窗口
*/
public ShapeFrame(){
this.setTitle("我的绘图应用");
this.setSize(800, 600);
//窗口大小是否可以改变
this.setResizable(false);
this.setLocationRelativeTo(null);
this.setDefaultCloseOperation(EXIT_ON_CLOSE);
}
//系统自动调用的方法，对窗口进行渲染
@Override
public void paint(Graphics g) {
super.paint(g);//相当于先画出了窗口，如果删除，窗口会出现残影
circle.draw(g);
rectangle.draw(g);
triangle.draw(g);
}
public static void main(String[] args) {
new ShapeFrame().setVisible(true);
}
}
package org.mobiletrain;
/**
* 车类(抽象类)
* @author apple
*
*/
public abstract class Vehicle {
protected String brand;//车的品牌
public Vehicle(String brand){
this.brand = brand;
}
/**
* 获得车的品牌
* @return 品牌
*/
public String getBrand() {
return brand;
}
//模板方法模式(GoF设计模式 - 23种)
/**
* 获得日租金(抽象方法)
* @return 日租金
*/
public abstract int rentPerDay();
/**
* 计算总租金
* @param days 天数
* @return 总租金
*/
public int calcRent(int days){
return days * rentPerDay();
}
}
package org.mobiletrain;
/**
* 汽车类
* @author apple
*
*/
public class Car extends Vehicle {
private boolean nomal;//判断是普通车还是商务车
/**
* 构造器
* @param brand 品牌
* @param normal 判断是普通车还是商务车
*/
public Car(String brand,boolean normal) {
super(brand);
this.nomal = normal;
}
@Override
public int rentPerDay() {
return nomal ? 400 : 600;
}
}
package org.mobiletrain;
/**
* 卡车类
* @author apple
*
*/
public class Truck extends Vehicle {
private double load;//载重
/**
* 构造器
* @param brand 品牌
* @param load 载重
*/
public Truck(String brand,double load) {
super(brand);
this.load = load;
}
@Override
public int rentPerDay() {
if (load < 10) {
return 1200;
}
else if (load < 20) {
return 2000;
}
else {
return 2500;
}
}
}
package org.mobiletrain.ui;
import org.mobiletrain.Car;
import org.mobiletrain.Truck;
import org.mobiletrain.Vehicle;
public class CarRentTest {
public static void main(String[] args) {
Vehicle v1 = new Car("奔驰", false);
System.out.println(v1.calcRent(5));
Vehicle v2 = new Truck("东风", 8);
System.out.println(v2.calcRent(1));
}
}
package org.mobiletrain.ui;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Image;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.JFrame;
@SuppressWarnings("serial")
public class Chess extends JFrame{
private Image knightImage;//骑士
private Image rookImage;//城堡
public Chess() {
this.setTitle("国际象棋");
this.setSize(800, 800);
this.setResizable(false);
this.setLocationRelativeTo(null);
this.setDefaultCloseOperation(EXIT_ON_CLOSE);
try {
knightImage = ImageIO.read(this.getClass().getClassLoader().getResource("22.png"));
rookImage = ImageIO.read(this.getClass().getClassLoader().getResource("21.png"));
}
catch (IOException e) {
e.printStackTrace();
}
}
@Override
public void paint(Graphics g) {
super.paint(g);
g.setColor(Color.gray);
g.fillRect(0, 0, 800, 800);
for (int i = 0; i < 8; i++) {
for (int j = 0; j < 8; j++) {
g.setColor((i + j) % 2 == 0 ? new Color(210, 220, 162) : new Color(179, 56, 89));
g.fillRect(40 + j * 90, 60 + i * 90, 90, 90);
}
}
g.drawImage(knightImage, 130, 60, 90, 90,null);
g.drawImage(rookImage, 40, 60, 90, 90,null);
}
}
package org.mobiletrain;
import org.mobiletrain.ui.Chess;
public class ChessTest{
public static void main(String[] args) {
new Chess().setVisible(true);
}
}
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