自己动手写一个滑动验证码组件（后端为Spring Boot项目）

以下是一个简单的滑动验证码后端接口的Spring Boot示例代码：

import org.springframework.http.MediaType;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.servlet.mvc.method.annotation.StreamingResponseBody;
 
import javax.imageio.ImageIO;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.OutputStream;
import java.io.IOException;
import java.util.Random;
 
@RestController
public class CaptchaController {
 
    @GetMapping(path = "/captcha", produces = MediaType.IMAGE_PNG_VALUE)
    public StreamingResponseBody getCaptcha() {
        return outputStream -> {
            // 创建图片
            BufferedImage image = new BufferedImage(200, 50, BufferedImage.TYPE_INT_RGB);
            Graphics2D g2d = image.createGraphics();
 
            // 设置背景颜色
            g2d.setColor(Color.WHITE);
            g2d.fillRect(0, 0, 200, 50);
 
            // 设置字体和颜色
            Font font = new Font("Arial", Font.BOLD, 40);
            g2d.setFont(font);
            g2d.setColor(Color.BLUE);
 
            // 绘制随机字符
            String randomStr = generateRandomString(4);
            g2d.drawString(randomStr, 20, 40);
 
            // 绘制干扰线
            drawDisturbLine(g2d, image);
 
            // 输出图片
            try {
                ImageIO.write(image, "png", outputStream);
            } catch (IOException e) {
                e.printStackTrace();
            }
 
            // 释放资源
            g2d.dispose();
            image.flush();
        };
    }
 
    private String generateRandomString(int length) {
        Random random = new Random();
        StringBuilder sb = new StringBuilder(length);
        for (int i = 0; i < length; i++) {
            sb.append((char) (random.nextInt(26) + 'A'));
        }
        return sb.toString();
    }
 
    private void drawDisturbLine(Graphics2D g2d, BufferedImage image) {
        Random random = new Random();
        for (int i = 0; i < 5; i++) {
            int x1 = random.nextInt(image.getWidth());
            int y1 = random.nextInt(image.getHeight());