springboot整合kaptcha验证码的示例代码

<!-- kaptcha验证码 -->
    <dependency>
    <groupId>com.github.penggle</groupId>
      <artifactId>kaptcha</artifactId>
      <version>2.3.2</version>
    </dependency>

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
  <!-- 生成kaptcha的bean-->
  <bean id="captchaProducer" class="com.google.code.kaptcha.impl.DefaultKaptcha">
    <property name="config">
      <bean class="com.google.code.kaptcha.util.Config">
        <constructor-arg type="java.util.Properties">
          <!--设置kaptcha属性 -->
          <props>
            <prop key = "kaptcha.border ">yes</prop>
            <prop key="kaptcha.border.color">105,179,90</prop>
            <prop key="kaptcha.textproducer.font.color">blue</prop>
            <prop key="kaptcha.image.width">100</prop>
            <prop key="kaptcha.image.height">50</prop>
            <prop key="kaptcha.textproducer.font.size">27</prop>
            <prop key="kaptcha.session.key">code</prop>
            <prop key="kaptcha.textproducer.char.length">4</prop>
            <prop key="kaptcha.textproducer.font.names">宋体,楷体,微软雅黑</prop>
            <prop key="kaptcha.textproducer.char.string">0123456789ABCEFGHIJKLMNOPQRSTUVWXYZ</prop>
            <prop key="kaptcha.obscurificator.impl">com.google.code.kaptcha.impl.WaterRipple</prop>
            <prop key="kaptcha.noise.color">black</prop>
            <prop key="kaptcha.noise.impl">com.google.code.kaptcha.impl.DefaultNoise</prop>
            <prop key="kaptcha.background.clear.from">185,56,213</prop>
            <prop key="kaptcha.background.clear.to">white</prop>
            <prop key="kaptcha.textproducer.char.space">3</prop>
          </props>
        </constructor-arg>
      </bean>
    </property>
  </bean>
</beans>

@Controller
public class CodeController {
  @Autowired
  private Producer captchaProducer = null;
  @RequestMapping("/kaptcha")
  public void getKaptchaImage(HttpServletRequest request, HttpServletResponse response) throws Exception {
    HttpSession session = request.getSession();
    response.setDateHeader("Expires", 0);
    response.setHeader("Cache-Control", "no-store, no-cache, must-revalidate");
    response.addHeader("Cache-Control", "post-check=0, pre-check=0");
    response.setHeader("Pragma", "no-cache");
    response.setContentType("image/jpeg");
    //生成验证码
    String capText = captchaProducer.createText();
    session.setAttribute(Constants.KAPTCHA_SESSION_KEY, capText);
    //向客户端写出
    BufferedImage bi = captchaProducer.createImage(capText);
    ServletOutputStream out = response.getOutputStream();
    ImageIO.write(bi, "jpg", out);
    try {
      out.flush();
    } finally {
      out.close();
    }
  }
}

public class CodeUtil {
  /**
   * 将获取到的前端参数转为string类型
   * @param request
   * @param key
   * @return
   */
  public static String getString(HttpServletRequest request, String key) {
    try {
      String result = request.getParameter(key);
      if(result != null) {
        result = result.trim();
      }
      if("".equals(result)) {
        result = null;
      }
      return result;
    }catch(Exception e) {
      return null;
    }
  }
  /**
   * 验证码校验
   * @param request
   * @return
   */
  public static boolean checkVerifyCode(HttpServletRequest request) {
    //获取生成的验证码
    String verifyCodeExpected = (String) request.getSession().getAttribute(com.google.code.kaptcha.Constants.KAPTCHA_SESSION_KEY);
    //获取用户输入的验证码
    String verifyCodeActual = CodeUtil.getString(request, "verifyCodeActual");
    if(verifyCodeActual == null ||!verifyCodeActual.equals(verifyCodeExpected)) {
      return false;
    }
    return true;
  }
}

@RestController
public class HelloWorld {
  @RequestMapping("/hello")
  public String hello(HttpServletRequest request) {
    if (!CodeUtil.checkVerifyCode(request)) {
      return "验证码有误！";
    } else {
      return "hello,world";
    }
  }
}

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <title>Title</title>
  <script type="text/javascript">
    function refresh() {
      document.getElementById('captcha_img').src="/kaptcha?"+Math.random();
    }
  </script>
</head>
<body>
<form action="/hello" method="post">
  验证码: <input type="text" placeholder="请输入验证码" name="verifyCodeActual">
  <div class="item-input">
    <img id="captcha_img" alt="点击更换" title="点击更换"
       onclick="refresh()" src="/kaptcha" />
  </div>
  <input type="submit" value="提交" />
</form>

</body>
</html>

@Configuration
public class KaptchaConfig {
  @Bean
  public DefaultKaptcha getDefaultKaptcha(){
    DefaultKaptcha captchaProducer = new DefaultKaptcha();
    Properties properties = new Properties();
    properties.setProperty("kaptcha.border", "yes");
    properties.setProperty("kaptcha.border.color", "105,179,90");
    properties.setProperty("kaptcha.textproducer.font.color", "blue");
    properties.setProperty("kaptcha.image.width", "110");
    properties.setProperty("kaptcha.image.height", "40");
    properties.setProperty("kaptcha.textproducer.font.size", "30");
    properties.setProperty("kaptcha.session.key", "code");
    properties.setProperty("kaptcha.textproducer.char.length", "4");
    properties.setProperty("kaptcha.textproducer.font.names", "宋体,楷体,微软雅黑");
    Config config = new Config(properties);
    captchaProducer.setConfig(config);
    return captchaProducer;

  }
}