java学习之Swing篇（三）——简单画板的实现v1.0

画板功能实现：

1、直线、矩形、椭圆、多边形、曲线等基本图形的绘制；

2、多种颜色可选；

3、橡皮檫采用加粗画笔，另添加一键清屏功能；

4、重绘功能；

5、多边形采用两种方式自动闭合：一种鼠标双击闭合，一种为切换其它图形自动闭合；

6、采用边界布局。

图形效果：

具体代码如下：

主界面程序

package paint0701;

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;

public class PainterUI extends JPanel {
	private static final long serialVersionUID = 1L;
	private Shape[] shapeParameter = new Shape[20000];

	public void initUI() {
		// 新建窗体并命名
		JFrame jf = new JFrame("画板");
		// 设置窗体大小
		jf.setSize(1100, 700);
		// 窗体设置居中
		jf.setLocationRelativeTo(null);
		// 设置窗体关闭
		jf.setDefaultCloseOperation(3);
		// 设置窗体边界布局
		jf.setLayout(new BorderLayout());

		// 添加3个JPanel容器
		JPanel jp2 = new JPanel();
		JPanel jp3 = new JPanel();
		// 将JPanel布局到窗体中
		jf.add(this, BorderLayout.CENTER);
		jf.add(jp2, BorderLayout.WEST);
		jf.add(jp3, BorderLayout.EAST);

		// 设置jp1
		this.setPreferredSize(new Dimension(900, 700));
		this.setBackground(Color.white);

		// 创建事件监听器对象
		DrawListener dl = new DrawListener();
		// 给画布添加监听器
		this.addMouseListener(dl);
		this.addMouseMotionListener(dl);

		// 设置jp2
		jp2.setPreferredSize(new Dimension(100, 700));
		jp2.setBackground(Color.LIGHT_GRAY);
		// 设置jp3
		jp3.setPreferredSize(new Dimension(100, 700));
		jp3.setBackground(Color.LIGHT_GRAY);

		// 添加图形按钮
		String[] shapeArray = { "直线", "矩形", "椭圆", "多边形", "画笔", "橡皮檫", "清屏" };
		for (int i = 0; i < shapeArray.length; i++) {
			// 创建图形按钮
			JButton jbu1 = new JButton(shapeArray[i]);
			// 设置按钮大小
			jbu1.setPreferredSize(new Dimension(100, 40));
			// 将按钮添加到jp2容器中
			jp2.add(jbu1);
			// 给按钮注册监听器
			jbu1.addActionListener(dl);
		}

		// 设置颜色按钮
		Color[] colorArray = { Color.red, Color.pink, Color.orange, Color.yellow, Color.green, Color.blue, Color.cyan,
				Color.black, Color.gray, Color.white };
		for (int i = 0; i < colorArray.length; i++) {
			JButton jbu2 = new JButton();
			jbu2.setBackground(colorArray[i]);
			jbu2.setPreferredSize(new Dimension(100, 40));
			jp3.add(jbu2);
			jbu2.addActionListener(dl);
		}

		// 设置窗体可见
		jf.setVisible(true);
		// 获取画笔
		Graphics g = this.getGraphics();
		// 将画笔传递过去
		dl.setGr(g);
		// 将图形数组传递过去
		dl.setSp(shapeParameter);
	}

	// 重写父类方法
	public void paint(Graphics g) {
		super.paint(g);
                //遍历图形数组，重绘图形
		for (int i = 0; i < shapeParameter.length; i++) {
			Shape shape = shapeParameter[i];
			if (shapeParameter[i] != null) {
				shape.drawShape(g);
			}
		}
	}
        //主函数
	public static void main(String[] args) {
		PainterUI pui = new PainterUI();
		pui.initUI();
	}
}

 

 

监听器

 

 

package paint0701;

import java.awt.BasicStroke;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseListener;
import java.awt.event.MouseMotionListener;
import javax.swing.JButton;

public class DrawListener implements MouseListener, MouseMotionListener, ActionListener {

	private int x1, y1, x2, y2, x3, y3, x4, y4, x5, y5;
	private Boolean flag1 = true, flag2 = false;
	private String name;
	private Color color;
	private Graphics g;
	private Shape[] shapeArray;
	private int index = 0;

	// 初始化画笔
	public void setGr(Graphics g) {
		this.g = g;
	}

	// 初始化图形数组
	public void setSp(Shape[] shapeArray) {
		this.shapeArray = shapeArray;
	}
	 //鼠标点击
	public void mouseClicked(java.awt.event.MouseEvent e) {
		flag2 = true;
		if (!flag1) {
			x5 = e.getX();
			y5 = e.getY();
			g.drawLine(x4, y4, x5, y5);
		      //将直线存入数组
			Shape line = new Line(x4, y4, x5, y5, name, color);
			shapeArray[index++] = line;

			x4 = x5;
			y4 = y5;
		}
		//双击自动完成多边形闭合
		if (e.getClickCount() == 2) {
			g.drawLine(x5, y5, x3, y3);

			Shape line = new Line(x5, y5, x3, y3, name, color);
			shapeArray[index++] = line;
			flag1 = true;
		}

	}
    //鼠标按下
	public void mousePressed(java.awt.event.MouseEvent e) {
		{
			x1 = e.getX();
			y1 = e.getY();
		}
	}
	//鼠标释放
	public void mouseReleased(java.awt.event.MouseEvent e) {

		{
			x2 = e.getX();
			y2 = e.getY();
			// 绘制直线
			if ("直线".equals(name)) {
				g.drawLine(x1, y1, x2, y2);
				Shape line = new Line(x1, y1, x2, y2, name, color);
				shapeArray[index++] = line;
			}
			if ("矩形".equals(name)) {
				g.drawRect(Math.min(x1, x2), Math.min(y1, y2), Math.abs(x2 - x1), Math.abs(y2 - y1));
				Shape rect = new Rect(x1, y1, x2, y2, name, color);
				shapeArray[index++] = rect;
			}
			if ("椭圆".equals(name)) {
				g.drawOval(Math.min(x1, x2), Math.min(y1, y2), Math.abs(x2 - x1), Math.abs(y2 - y1));
				Shape oval = new Oval(x1, y1, x2, y2, name, color);
				shapeArray[index++] = oval;
			}

			if ("多边形".equals(name) && flag1) {
				g.drawLine(x1, y1, x2, y2);

				Shape line = new Line(x1, y1, x2, y2, name, color);
				shapeArray[index++] = line;

				x3 = x1;
				y3 = y1;
				x4 = x2;
				y4 = y2;

				flag1 = false;
			}

		}

	}

	public void mouseEntered(java.awt.event.MouseEvent e) {
	}

	public void mouseExited(java.awt.event.MouseEvent e) {
	}
	//鼠标拖动
	public void mouseDragged(java.awt.event.MouseEvent e) {
		// 画笔重载需注意内存
		if ("画笔".equals(name)) {
			x2 = e.getX();
			y2 = e.getY();
			g.drawLine(x1, y1, x2, y2);
			Shape line = new Line(x1, y1, x2, y2, name, color);
			shapeArray[index++] = line;
			x1 = x2;
			y1 = y2;
		}
		if ("橡皮檫".equals(name)) {
			color = Color.white;
			g.setColor(color);
			//设置线宽
			((Graphics2D) g).setStroke(new BasicStroke(20));
			x2 = e.getX();
			y2 = e.getY();
			g.drawLine(x1, y1, x2, y2);
			Shape eraser = new Eraser(x1, y1, x2, y2, name, color);
			shapeArray[index++] = eraser;
			x1 = x2;
			y1 = y2;
			color = Color.black;
			g.setColor(color);
			((Graphics2D) g).setStroke(new BasicStroke(1));
		}
	}

	public void mouseMoved(java.awt.event.MouseEvent e) {

	}

	public void actionPerformed(ActionEvent e) {
		
		if ("".equals(e.getActionCommand())) {
			// 获取当前事件源，并强制转换
			JButton jb = (JButton) e.getSource();
			// 将按钮背景色赋值给color
			color = jb.getBackground();
			// 设置画笔背景色
			// 注意：不能直接写成g.setColor(jb.getBackground());后面重绘时需用到color参数；
			g.setColor(color);
		} else {
			name = e.getActionCommand();

			if ("清屏".equals(name)) {
				color = Color.white;
				g.setColor(color);
				x1 = 0;
				y1 = 0;
				x2 = 900;
				y2 = 700;
				g.fillRect(x1, y1, x2, y2);
				
				// 重置多边形最后一条线段数据
				x3 = 0;
				y3 = 0;
				x5 = 0;
				y5 = 0;
				

				Shape fillrect = new FillRect(x1, y1, x2, y2, name, color);
				shapeArray[index++] = fillrect;
				color = Color.black;
				g.setColor(color);
			}

		}

		// 多边形切换设置
		flag1 = true;
		// 点击非清屏按钮，先完成多边形绘制
		if (!"".equals(e.getActionCommand()) && flag2) {
			g.drawLine(x5, y5, x3, y3);

			Shape line = new Line(x5, y5, x3, y3, name, color);
			shapeArray[index++] = line;

			flag2 = false;
		}
		// 点击颜色按钮继续画图
		if ("".equals(e.getActionCommand()) && flag2) {
			flag1 = false;
		}
	}
}

 

 

Shape父类

package paint0701;

import java.awt.Color;
import java.awt.Graphics;

public abstract class Shape {
	public int x1, y1, x2, y2;
	public String name;
	public Color color;

	public Shape() {
	};

	public Shape(int x1, int y1, int x2, int y2, String name, Color color) {
		this.x1 = x1;
		this.y1 = y1;
		this.x2 = x2;
		this.y2 = y2;
		this.name = name;
		this.color = color;
	}

	public void drawShape(Graphics g) {

	}
}

 

直线子类

 

package paint0701;

import java.awt.Color;
import java.awt.Graphics;

public class Line extends Shape {
	public Line() {
	};

	public Line(int x1, int y1, int x2, int y2, String name, Color color) {
		super(x1, y1, x2, y2, name, color);
	}

	public void drawShape(Graphics g) {
		g.setColor(color);
		g.drawLine(x1, y1, x2, y2);
	}

}

矩形子类

package paint0701;

import java.awt.Color;
import java.awt.Graphics;

public class Rect extends Shape {
	public Rect(){};
	public Rect(int x1,int y1,int x2,int y2,String name,Color color){
		super(x1,y1,x2,y2,name,color);
	}
	
	public void drawShape(Graphics g){
		g.setColor(color);
		g.drawRect(Math.min(x1, x2), Math.min(y1, y2), Math.abs(x2 - x1), Math.abs(y2 - y1));
		
	}
}

椭圆子类

package paint0701;

import java.awt.Color;
import java.awt.Graphics;

public class Oval extends Shape {
	public Oval(){};
	public Oval(int x1,int y1,int x2,int y2,String name,Color color){
		super(x1,y1,x2,y2,name,color);
	}
	
	public void drawShape(Graphics g){
		g.setColor(color);
		g.drawOval(Math.min(x1, x2), Math.min(y1, y2), Math.abs(x2 - x1), Math.abs(y2 - y1));
		
	}
}

清屏（绘制实心矩形）子类

package paint0701;

import java.awt.Color;
import java.awt.Graphics;

public class FillRect extends Shape {
	public FillRect() {
	};

	public FillRect(int x1, int y1, int x2, int y2, String name, Color color) {
		super(x1, y1, x2, y2, name, color);
	}

	public void drawShape(Graphics g) {
		g.setColor(color);
		g.fillRect(x1, y1, x2, y2);
	}

}

橡皮檫（绘制白色画笔）子类

package paint0701;

import java.awt.BasicStroke;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;

public class Eraser extends Shape {
	public Eraser() {
	};

	public Eraser(int x1, int y1, int x2, int y2, String name, Color color) {
		super(x1, y1, x2, y2, name, color);
	}

	public void drawShape(Graphics g) {
		g.setColor(color);
		((Graphics2D) g).setStroke(new BasicStroke(20));
		g.drawLine(x1, y1, x2, y2);
		((Graphics2D) g).setStroke(new BasicStroke(1));
	}
}

此画图板缺陷：

1、未增加调整线宽功能；

2、设计布局不够简洁；

3、为了完成多边形切换图形自动绘制新引入了多个变量，并且带来了一个相对明显的bug。

    （绘图时切换颜色按钮后，鼠标双击会有意外惊喜～）