生成验证码的工具类

import javax.imageio.ImageIO;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.io.OutputStream;
import java.util.Random;

public class VerificationCode {

    /**
     * 生成验证码图片的宽度
     */
    private final int width = 100;
    /**
     * 生成验证码图片的高度
     */
    private final int height = 30;
    private final String[] fontNames = {"宋体", "楷体", "隶书", "微软雅黑"};
    /**
     * 定义验证码图片的背景颜色为白色
     */
    private final Color bgColor = new Color(255, 255, 255);
    private final Random random = new Random();
    private final String codes = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
    /**
     * 记录随机字符串
     */
    private String text;

	/**
	 * 获取一个随意颜色
	 * 
	 * @return
	 */
	private Color randomColor() {
		int red = random.nextInt(150);
		int green = random.nextInt(150);
		int blue = random.nextInt(150);
		return new Color(red, green, blue);
	}

	/**
	 * 获取一个随机字体
	 * 
	 * @return
	 */
	private Font randomFont() {
		String name = fontNames[random.nextInt(fontNames.length)];
		int style = random.nextInt(4);
		int size = random.nextInt(5) + 24;
		return new Font(name, style, size);
	}

	/**
	 * 获取一个随机字符
	 * 
	 * @return
	 */
	private char randomChar() {
		return codes.charAt(random.nextInt(codes.length()));
	}

	/**
	 * 创建一个空白的BufferedImage对象
	 * 
	 * @return
	 */
	private BufferedImage createImage() {
		BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
		Graphics2D g2 = (Graphics2D) image.getGraphics();
		g2.setColor(bgColor);// 设置验证码图片的背景颜色
		g2.fillRect(0, 0, width, height);
		return image;
	}

	public BufferedImage getImage() {
		BufferedImage image = createImage();
		Graphics2D g2 = (Graphics2D) image.getGraphics();
		StringBuffer sb = new StringBuffer();
		for (int i = 0; i < 4; i++) {
			String s = randomChar() + "";
			sb.append(s);
			g2.setColor(randomColor());
			g2.setFont(randomFont());
			float x = i * width * 1.0f / 4;
			g2.drawString(s, x, height - 8);
		}
		this.text = sb.toString();
		drawLine(image);
		return image;
	}

	/**
	 * 绘制干扰线
	 * 
	 * @param image
	 */
	private void drawLine(BufferedImage image) {
		Graphics2D g2 = (Graphics2D) image.getGraphics();
		int num = 5;
		for (int i = 0; i < num; i++) {
			int x1 = random.nextInt(width);
			int y1 = random.nextInt(height);
			int x2 = random.nextInt(width);
			int y2 = random.nextInt(height);
			g2.setColor(randomColor());
			g2.setStroke(new BasicStroke(1.5f));
			g2.drawLine(x1, y1, x2, y2);
		}
	}

	public String getText() {
		return text;
	}

	public static void output(BufferedImage image, OutputStream out) throws IOException {
		ImageIO.write(image, "JPEG", out);
	}

@RestController
public class LoginController {

    @GetMapping("/verifyCode")
    public void verifyCode(HttpServletRequest request, HttpServletResponse resp) throws IOException {
        VerificationCode code = new VerificationCode();
        BufferedImage image = code.getImage();
        String text = code.getText();
        HttpSession session = request.getSession(true);
        session.setAttribute("verify_code", text);
        VerificationCode.output(image,resp.getOutputStream());
    }
}