Java：使用 Graphics2D 类来绘制图像

过程介绍

创建一个 BufferedImage 对象

• 首先创建一个 BufferedImage 对象来表示图像

创建一个 Graphics2D 对象

• 然后使用 createGraphics() 方法创建一个 Graphics2D 对象

绘制字符和干扰线

• 最后通过该对象绘制字符和干扰线。

将生成的图像保存到文件

• 使用 ImageIO.write() 方法将生成的图像保存到文件中，或者将其输出到控制台。

示例代码

import java.awt.*;  
import java.awt.image.BufferedImage;  
import java.util.Random;public class CaptchaGenerator {private static final String CHAR_POOL = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";  private static final int WIDTH = 160;  private static final int HEIGHT = 50;  private static final int CHAR_NUM = 4;  private static final int LINE_NUM = 10;public static void main(String[] args) {  BufferedImage captchaImage = generateCaptchaImage();  // 保存图片到文件  // ImageIO.write(captchaImage, "png", new File("captcha.png"));  // 输出图片到控制台  ImageIO.write(captchaImage, "png", System.out);  }private static BufferedImage generateCaptchaImage() {  BufferedImage image = new BufferedImage(WIDTH, HEIGHT, BufferedImage.TYPE_INT_RGB);  Graphics2D g = image.createGraphics();  Random random = new Random();// 设置背景颜色  g.setColor(Color.WHITE);  g.fillRect(0, 0, WIDTH, HEIGHT);// 绘制字符  for (int i = 0; i < CHAR_NUM; i++) {  g.setColor(getRandomColor());  char c = getRandomChar();  g.drawString(String.valueOf(c), 30 * i + 20, 30);  }// 绘制干扰线  for (int i = 0; i < LINE_NUM; i++) {  g.setColor(getRandomColor());  int x1 = random.nextInt(WIDTH);  int y1 = random.nextInt(HEIGHT);  int x2 = random.nextInt(WIDTH);  int y2 = random.nextInt(HEIGHT);  g.drawLine(x1, y1, x2, y2);  }g.dispose();  return image;  }private static Color getRandomColor() {  Random random = new Random();  int r = random.nextInt(256);  int g = random.nextInt(256);  int b = random.nextInt(256);  return new Color(r, g, b);  }private static char getRandomChar() {  Random random = new Random();  int index = random.nextInt(CHAR_POOL.length());  return CHAR_POOL.charAt(index);  }  
}