SpringBoot实现前端验证码图片生成和校验的实例讲解

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 void 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("Times New Roman", 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);
  //将生成的随机字符串保存到session中
  session.removeAttribute(RANDOMCODEKEY);
  session.setAttribute(RANDOMCODEKEY, 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);
  }

 }

 /**
  * 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));
 }
}

/**
 * 生成验证码
 */
@RequestMapping(value = "/getVerify")
public void getVerify(HttpServletRequest request, HttpServletResponse response) {
 try {
  response.setContentType("image/jpeg");//设置相应类型,告诉浏览器输出的内容为图片
  response.setHeader("Pragma", "No-cache");//设置响应头信息，告诉浏览器不要缓存此内容
  response.setHeader("Cache-Control", "no-cache");
  response.setDateHeader("Expire", 0);
  RandomValidateCodeUtil randomValidateCode = new RandomValidateCodeUtil();
  randomValidateCode.getRandcode(request, response);//输出验证码图片方法
 } catch (Exception e) {
  logger.error("获取验证码失败>>>> ", e);
 }
}

<div class="row">
 <div class="col-xs-6 pull_left">
  <div class="form-group">
   <input class="form-control" type="tel" id="verify_input" placeholder="请输入验证码" maxlength="4">
  </div>
 </div>
 <div class="col-xs-6 pull_left">
  <a href="javascript:void(0);" rel="external nofollow" title="点击更换验证码">
   <img id="imgVerify" src="" alt="更换验证码" height="36" width="100%" onclick="getVerify(this);">
  </a>
 </div>
</div>

//获取验证码
function getVerify(obj){
 obj.src = httpurl + "/sys/getVerify?"+Math.random();
}

/**
 * 忘记密码页面校验验证码
 */
@RequestMapping(value = "/checkVerify", method = RequestMethod.POST, headers = "Accept=application/json")
public boolean checkVerify(@RequestBody Map<String, Object> requestMap, HttpSession session) {
 try{
  //从session中获取随机数
  String inputStr = requestMap.get("inputStr").toString();
  String random = (String) session.getAttribute("RANDOMVALIDATECODEKEY");
  if (random == null) {
   return false;
  }
  if (random.equals(inputStr)) {
   return true;
  } else {
   return false;
  }
 }catch (Exception e){
  logger.error("验证码校验失败", e);
  return false;
 }
}