javaWeb如何实现随机图片验证码详解

public class RandomValidateCodeUtil {


 public static final String RANDOMCODEKEY = "RANDOMVALIDATECODEKEY";//放到session中的key
 private String randString = "0123456789";//随机产生只有数字的字符串 private String
 //private String randString = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";//随机产生只有字母的字符串
 //private String randString = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";//随机产生数字与字母组合的字符串
 private int width = 95;// 图片宽
 private int height = 25;// 图片高
 private int lineSize = 40;// 干扰线数量
 private int stringNum = 4;// 随机产生字符数量

 private static final Logger logger = LoggerFactory.getLogger(RandomValidateCodeUtil.class);

 private Random random = new Random();

 /**
  * 获得字体
  */
 private Font getFont() {
  return new Font("Fixedsys", Font.CENTER_BASELINE, 18);
 }

 /**
  * 获得颜色
  */
 private Color getRandColor(int fc, int bc) {
  if (fc > 255) {
   fc = 255;
  }
  if (bc > 255) {
   bc = 255;
  }
  int r = fc + random.nextInt(bc - fc - 16);
  int g = fc + random.nextInt(bc - fc - 14);
  int b = fc + random.nextInt(bc - fc - 18);
  return new Color(r, g, b);
 }

 /**
  * 生成随机图片
  */
 public String getRandcode(HttpServletRequest request, HttpServletResponse response) {
  HttpSession session = request.getSession();
  // BufferedImage类是具有缓冲区的Image类,Image类是用于描述图像信息的类
  BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_BGR);
  Graphics g = image.getGraphics();// 产生Image对象的Graphics对象,改对象可以在图像上进行各种绘制操作
  g.fillRect(0, 0, width, height);//图片大小
  g.setFont(new Font("Default", Font.ROMAN_BASELINE, 18));//字体大小
  g.setColor(getRandColor(110, 133));//字体颜色
  // 绘制干扰线
  for (int i = 0; i <= lineSize; i++) {
   drowLine(g);
  }
  // 绘制随机字符
  String randomString = "";
  for (int i = 1; i <= stringNum; i++) {
   randomString = drowString(g, randomString, i);
  }
  logger.info(randomString);
  g.dispose();
  try {
   // 将内存中的图片通过流动形式输出到客户端
   ImageIO.write(image, "JPEG", response.getOutputStream());
  } catch (Exception e) {
   logger.error("将内存中的图片通过流动形式输出到客户端失败>>>> ", e);
  }
  return randomString;
 }

 /**
  * 绘制字符串
  */
 private String drowString(Graphics g, String randomString, int i) {
  g.setFont(getFont());
  g.setColor(new Color(random.nextInt(101), random.nextInt(111), random
    .nextInt(121)));
  String rand = String.valueOf(getRandomString(random.nextInt(randString
    .length())));
  randomString += rand;
  g.translate(random.nextInt(3), random.nextInt(3));
  g.drawString(rand, 13 * i, 16);
  return randomString;
 }

 /**
  * 绘制干扰线
  */
 private void drowLine(Graphics g) {
  int x = random.nextInt(width);
  int y = random.nextInt(height);
  int xl = random.nextInt(13);
  int yl = random.nextInt(15);
  g.drawLine(x, y, x + xl, y + yl);
 }

 /**
  * 获取随机的字符
  */
 public String getRandomString(int num) {
  return String.valueOf(randString.charAt(num));
 }
}

 @GetMapping(value = "/getVerify")
 @ApiOperation("生成图片验证码")
 public void getVerify(HttpServletRequest request, HttpServletResponse response) {
  try {
   //设置相应类型,告诉浏览器输出的内容为图片
   response.setContentType("image/jpeg");
   //设置响应头信息，告诉浏览器不要缓存此内容
   response.setHeader("Pragma", "No-cache");
   response.setHeader("Cache-Control", "no-cache");
   response.setDateHeader("Expire", 0);
   RandomValidateCodeUtil randomValidateCode = new RandomValidateCodeUtil();
   //输出验证码图片方法
   String randcode = randomValidateCode.getRandcode(request, response);
   
   // 将随机生成的字符串放在redis中
   redisUtil.save("random", randcode);
   
   // 将生成的随机字符串保存到session中
   // HttpSession session = request.getSession();
   // session.removeAttribute(RANDOMCODEKEY);
   // session.setAttribute(RANDOMCODEKEY, randomString);

  } catch (Exception e) {
   log.error("获取验证码失败>>>> ", e);
  }
 }

@PostMapping("/checkVerify")
  @ApiOperation("校验图形验证码")
  public String checkValidateCode(String verify) {
    // 校验验证码
    try {
      // 从redis中获取验证码
      String random = (String) redisUtil.findKey("random");

      // 从ression中获取验证码
      HttpSession session = request.getSession();
      String random = session.getAttribute("random");

      log.info("获取的随机数 random = {}", random);
      if (org.springframework.util.StringUtils.isEmpty(verify)) {
        return "没有输入验证码";
      }
      if (verify.equals(random)) {
        redisUtil.delKey("random");
      } else {
        return "验证码错误";
      }
    } catch (Exception e) {
      log.error("验证码校验失败", e);
      return "服务器异常";
    }
    return "成功";
  }