1、工具类

import org.apache.xmlbeans.impl.util.Base64;
import org.springframework.web.context.WebApplicationContext;
import org.springframework.web.context.support.WebApplicationContextUtils;import javax.imageio.ImageIO;
import javax.servlet.ServletContext;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.ByteArrayOutputStream;
import java.util.HashMap;
import java.util.Map;
import java.util.Random;
import java.util.UUID;public class CaptchaGenerator {private static Logger log = LoggerFactory.getLogger(CaptchaGenerator.class);// 图像宽度private static final int WIDTH = 100;// 图像高度private static final int HEIGHT = 35;// 验证码字符集合private static final String CHARACTERS = "AaBbCcDdEeFfGgHhIiJjKkLlMmNnOoPpQqRrSsTtUuVvWwXxYyZz";// 字符随机颜色private static Color getColor(Random random) {return new Color(random.nextInt(256), random.nextInt(256), random.nextInt(256));}// 生成验证码，使用 response直接输出图片，也可以返回base64图片public static void generate(HttpServletRequest request, HttpServletResponse response) throws Exception {try {BufferedImage image = new BufferedImage(WIDTH, HEIGHT, BufferedImage.TYPE_INT_RGB);Graphics g = image.getGraphics();//设置背景颜色g.setColor(Color.PINK);g.fillRect(0,0,WIDTH,HEIGHT);Random random = new Random();StringBuilder captchaText = new StringBuilder();for (int i = 0; i < 4; ++i) {char c = CHARACTERS.charAt(random.nextInt(CHARACTERS.length()));captchaText.append(c);Font font = new Font("Arial", Font.BOLD, 20);Color color = getColor(random);g.setFont(font);// 设置字符颜色g.setColor(color);g.drawString(Character.toString(c), 20 * i + 10, 20);}// 如果使用 ip + 缓存来存储验证码，那么不需要 HttpSession，看个人具体实现HttpSession session = request.getSession();session.removeAttribute("captcha");session.setAttribute("captcha",captchaText.toString());log.info("==== CaptchaGenerator session id==========:{}",session.getId());g.dispose();log.info("====generate Captcha============" + captchaText);log.info("====generate Captcha sesstion captcha============" + session.getAttribute("captcha"));ServletOutputStream responseOutputStream =response.getOutputStream();ImageIO.write(image, "png", responseOutputStream);// 直接 response输出responseOutputStream.flush();responseOutputStream.close();// 转为base64图片// ByteArrayOutputStream baos = new ByteArrayOutputStream();// byte[] imageBytes = baos.toByteArray();// 关闭 ByteArrayOutputStream// baos.close();// 将 byte 数组转换为 Base64 字符串// String base64Image = java.util.Base64.getEncoder().encodeToString(imageBytes);// 打印 Base64 字符串// System.out.println(base64Image);} catch (Exception e) {e.printStackTrace();throw new Exception(e.getMessage());}}}

2、调用

	@RequestMapping(value="/loginCaptcha",method=RequestMethod.GET)public void loginCaptcha(HttpServletRequest request, HttpServletResponse response) throws Exception {CaptchaGenerator.generate(request,response);}