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java如何画点

2026-02-05 04:58:44Java

绘制单个点的方法

在Java中绘制单个点可以通过Graphics或Graphics2D类实现。以下是使用paintComponent方法在Swing组件上绘制点的示例代码：

import javax.swing.*;
import java.awt.*;

public class DrawPoint extends JPanel {
    @Override
    protected void paintComponent(Graphics g) {
        super.paintComponent(g);
        g.setColor(Color.RED);
        g.drawLine(50, 50, 50, 50); // 绘制单个点
    }

    public static void main(String[] args) {
        JFrame frame = new JFrame("Draw Point");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.add(new DrawPoint());
        frame.setSize(300, 300);
        frame.setVisible(true);
    }
}

使用Graphics2D绘制点

Graphics2D提供了更灵活的绘制方式，可以通过设置笔触（Stroke）来控制点的大小：

java如何画点

import javax.swing.*;
import java.awt.*;

public class DrawPoint2D extends JPanel {
    @Override
    protected void paintComponent(Graphics g) {
        super.paintComponent(g);
        Graphics2D g2d = (Graphics2D) g;
        g2d.setColor(Color.BLUE);
        g2d.setStroke(new BasicStroke(5)); // 设置点的大小
        g2d.drawLine(100, 100, 100, 100);
    }

    public static void main(String[] args) {
        JFrame frame = new JFrame("Draw Point with Graphics2D");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.add(new DrawPoint2D());
        frame.setSize(300, 300);
        frame.setVisible(true);
    }
}

绘制多个点的方法

通过循环或数组可以批量绘制多个点。以下示例展示如何绘制一组随机点：

import javax.swing.*;
import java.awt.*;
import java.util.Random;

public class DrawMultiplePoints extends JPanel {
    private static final int POINT_COUNT = 20;
    private final Random random = new Random();

    @Override
    protected void paintComponent(Graphics g) {
        super.paintComponent(g);
        Graphics2D g2d = (Graphics2D) g;
        g2d.setColor(Color.GREEN);

        for (int i = 0; i < POINT_COUNT; i++) {
            int x = random.nextInt(getWidth());
            int y = random.nextInt(getHeight());
            g2d.fillOval(x, y, 3, 3); // 使用填充椭圆作为点
        }
    }

    public static void main(String[] args) {
        JFrame frame = new JFrame("Multiple Points");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.add(new DrawMultiplePoints());
        frame.setSize(400, 400);
        frame.setVisible(true);
    }
}

使用fillOval方法绘制实心点

fillOval方法可以绘制实心圆点，通过控制直径大小实现不同尺寸的点：

java如何画点

import javax.swing.*;
import java.awt.*;

public class SolidPoint extends JPanel {
    @Override
    protected void paintComponent(Graphics g) {
        super.paintComponent(g);
        g.setColor(Color.MAGENTA);
        g.fillOval(150, 150, 10, 10); // 绘制直径为10的实心点
    }

    public static void main(String[] args) {
        JFrame frame = new JFrame("Solid Point");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.add(new SolidPoint());
        frame.setSize(300, 300);
        frame.setVisible(true);
    }
}

在BufferedImage上绘制点

对于离屏绘图，可以使用BufferedImage作为绘图表面：

import javax.swing.*;
import java.awt.*;
import java.awt.image.BufferedImage;

public class ImagePoint extends JPanel {
    private final BufferedImage image;

    public ImagePoint() {
        image = new BufferedImage(200, 200, BufferedImage.TYPE_INT_ARGB);
        Graphics2D g2d = image.createGraphics();
        g2d.setColor(Color.CYAN);
        g2d.fillOval(90, 90, 20, 20);
        g2d.dispose();
    }

    @Override
    protected void paintComponent(Graphics g) {
        super.paintComponent(g);
        g.drawImage(image, 50, 50, this);
    }

    public static void main(String[] args) {
        JFrame frame = new JFrame("Point on Image");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.add(new ImagePoint());
        frame.setSize(300, 300);
        frame.setVisible(true);
    }
}