java.awt.Graphics
线
package com.even.shape;
import java.awt.Graphics;
public class Line extends Shape {
@Override
public void draw(Graphics g) {
g.setColor(Color);
g.drawLine(starx, stary, endx, endy);
}
public int getLength(){
return (int) Math.sqrt((getStarx() - getEndx())
* (getStarx() - getEndx())
+ (getStary() - getEndy())
* (getStary() - getEndy()));
}
}
椭圆
package com.even.shape;
import java.awt.Graphics;
public class Oval extends Shape {
@Override
public void draw(Graphics g) {
g.setColor(Color);
int width = Math.abs(endx - starx); //横坐标的绝对值
int height = Math.abs(endy - stary); //纵坐标的绝对值
int x = starx < endx? starx : endx;
int y = stary < endy? stary : endy;
g.drawOval(x, y, width, height);
}
public int getArea() {
int width = Math.abs(endx - starx);
int height = Math.abs(endy - stary);
return (int) (Math.PI * width / 2 * height / 2);
}
public int getPerimeter() {
int width = Math.abs(endx - starx);
int height = Math.abs(endy - stary);
width = (width > height ? width : height);
height = (width < height ? width : height);
return (int) (2 * Math.PI * height / 2 + 4 * (width / 2 - height / 2));
}
}
长方形
package com.even.shape;
import java.awt.Graphics;
public class Rectangle extends Shape {
@Override
public void draw(Graphics g) {
g.setColor(Color);
int width = Math.abs(endx - starx); //横坐标的绝对值
int height = Math.abs(endy - stary); //纵坐标的绝对值
int x = starx < endx? starx : endx;
int y = stary < endy? stary : endy;
g.drawRect(x, y, width, height);
}
public int getArea() {
int width = Math.abs(endx - starx);
int height = Math.abs(endy - stary);
return width * height;
}
public int getPerimeter() {
int width = Math.abs(endx - starx);
int height = Math.abs(endy - stary);
return 2 * (width + height);
}
}
超类图形
package com.even.shape;
import java.awt.Color;
import java.awt.Graphics;
/** * 图形 （抽象类，不能实例化） */
public abstract class Shape {
protected int starx; //起点横坐标
protected int stary; //类推
protected int endx;
protected int endy;
protected Color Color; //颜色
public Color getColor() {
return Color;
}
public void setColor(Color color) {
Color = color;
}
/** * 抽象方法（留给子类去实现） * @param g 画笔 */
public abstract void draw(Graphics g);
public int getStarx() {
return starx;
}
public void setStarx(int starx) {
this.starx = starx;
}
public int getStary() {
return stary;
}
public void setStary(int stary) {
this.stary = stary;
}
public int getEndx() {
return endx;
}
public void setEndx(int endx) {
this.endx = endx;
}
public int getEndy() {
return endy;
}
public void setEndy(int endy) {
this.endy = endy;
}
}
我的窗口设计
package com.even.ui;
import java.awt.FlowLayout;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import com.even.shape.Line;
import com.even.shape.Oval;
import com.even.shape.Rectangle;
import com.even.shape.Shape;
import com.even.util.MyUtil;
@SuppressWarnings("serial")
public class Myframe extends JFrame {
private class ButtonHandler implements ActionListener{
@Override
public void actionPerformed(ActionEvent e) {
String command = e.getActionCommand();
if(command.equals("Line")){
shape = new Line();
}
else if(command.equalsIgnoreCase("Oval")) {
shape = new Oval();
}
else{
shape = new Rectangle();
}
shape.setStarx(MyUtil.random(1, 600));
shape.setStary(MyUtil.random(1, 600));
shape.setEndx(MyUtil.random(1, 600));
shape.setEndy(MyUtil.random(1, 600));
shape.setColor(MyUtil.randomColor());
repaint();
if (shape instanceof Line) {
str = "直线的长度" + ((Line) shape).getLength();
} else if (shape instanceof Oval) {
str = " 椭圆的面积:" + ((Oval) shape).getArea()
+ " 椭圆的周长为：" + ((Oval) shape).getPerimeter();
} else {
str = " 矩形的面积:" + ((Rectangle) shape).getArea()
+ " 矩形的周长为：" + ((Rectangle) shape).getPerimeter();
}
}
}
private JButton lineButton, ovalButton, rectButton;
private Shape shape = null;
private String str;
public Myframe() {
this.setTitle("绘制窗口"); // 窗口题目
this.setSize(1000, 800); // 窗口尺寸
this.setResizable(false); // 设置窗口大小不可改变
this.setLocationRelativeTo(null); // 设置窗口的相对位置
this.setDefaultCloseOperation(EXIT_ON_CLOSE); // 关掉窗口即结束程序
lineButton = new JButton("Line");
ovalButton = new JButton("Oval");
rectButton = new JButton("Rectangle");
ActionListener handler = new ButtonHandler();
lineButton.addActionListener(handler);
ovalButton.addActionListener(handler);
rectButton.addActionListener(handler);
this.setLayout(new FlowLayout());
this.add(lineButton);
this.add(ovalButton);
this.add(rectButton);
}
@Override
public void paint(Graphics g) {
super.paint(g);
if (shape != null) {
shape.draw(g);
g.drawString(str, 300, 300);
}
}
}
我的工具包
package com.even.util;
/** * 我的工具空间 */
import java.awt.Color;
public final class MyUtil { // 加个final，不让继承，成为终结类（断子绝孙类）
private MyUtil() { //禁止创建对象调用， 用只需类名 加“.”
}
/** * 产生指定范围的随机整数 * * @param min * 最小值（闭区间） * @param max * 最大值 （闭区间） * @return 指定范围的随机整数 */
public static int random(int min, int max) {
return (int) (Math.random() * (max - min + 1) + min);
}
/** * 生成随机颜色 * * @return Color 对象 */
public static Color randomColor() {
int r = random(0, 255);
int g = random(0, 255);
int b = random(0, 255);
return new Color(r, g, b);
}
}
我的窗口测试运行
package com.even.test;
import com.even.ui.Myframe;
public class MyFrameTest {
public static void main(String[] args) {
new Myframe().setVisible(true);
}
}