SpringMVC 生成验证码

使用 Google kaptcha 为 SpringMVC Maven 项目生成验证码

##1 添加依赖

        <dependency>
            <groupId>com.github.penggle</groupId>
            <artifactId>kaptcha</artifactId>
            <version>2.3.2</version>
        </dependency>

2 配置文件中添加验证码生成器Bean

    <!--图片验证码-->
    <bean id="captchaProducer" class="com.google.code.kaptcha.impl.DefaultKaptcha">
        <property name="config">
            <bean class="com.google.code.kaptcha.util.Config">
                <constructor-arg>
                    <props>
                        <prop key="kaptcha.border">no</prop>
                        <prop key="kaptcha.image.width">120</prop>
                        <prop key="kaptcha.session.key">code</prop>
                        <prop key="kaptcha.textproducer.font.color">blue</prop>
                        <prop key="kaptcha.textproducer.font.size">40</prop>
                        <prop key="kaptcha.textproducer.char.length">4</prop>
                    </props>
                </constructor-arg>
            </bean>
        </property>
    </bean>

• 配置项

3 页面添加验证码图片和输入框

            <div class="col-md-12">
                <div class="col-md-7 form-control"  style="float:left; width: 60%;">
                    <input type="text" id="validateCode" name="validateCode" placeholder="验证码" >
                </div>
                <div class="col-md-3" style="float: right;overflow: visible !important;">
                    <img src="./loadValidateCode" id="validateCodeImage" name="validateCodeImage"
                         style="width: 100px;height: 35px;"  onclick="loadValidateCode()" >
                </div>
            </div>

4 页面添加刷新验证码

    // 加载验证码
    function loadValidateCode() {
        var time = new Date().getTime();
        $("#validateCodeImage").attr('src', './loadValidateCode')
    }

5 后台添加生成验证码

• 导入包

    import com.google.code.kaptcha.Producer;

• 生成方法

    @Autowired
    private Producer captchaProducer;

    private final String VALIDATE_CODE = "VALIDATE_CODE";

    private final String EXPIRE_TIME = "EXPIRE_TIME";
    
    @RequestMapping(value = "/loadValidateCode", method = RequestMethod.GET)
    public void loadValidateCode(HttpServletRequest request, HttpServletResponse response) {
        try {
            HttpSession session = request.getSession();

            // 设置清除浏览器缓存
            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/png");

            // 验证码一分钟内有效
            long expireTime = System.currentTimeMillis() + 60000;
            
            // 将验证码放到session中
            String validateCode = captchaProducer.createText();
            session.setAttribute(VALIDATE_CODE, Utils.encodeBase64(validateCode));//将加密后的验证码放到session中，确保安全
            session.setAttribute(EXPIRE_TIME, expireTime);

            // 输出验证码图片
            BufferedImage bufferedImage = captchaProducer.createImage(validateCode);
            ServletOutputStream out = response.getOutputStream();
            ImageIO.write(bufferedImage, "png", out);
            out.flush();
            out.close();

        } catch (IOException e) {
            e.printStackTrace();
        }
    }

6 登录时校验验证码

    @RequestMapping(value = "/login", method = RequestMethod.POST)
    public @ResponseBody String login(String username, String password, String validateCode) {
        
        // 校验验证码是否有效
        String currentValidateCode = String.valueOf(request.getSession().getAttribute(VALIDATE_CODE));
        if (System.currentTimeMillis() > Long.parseLong(String.valueOf(request.getSession().getAttribute(EXPIRE_TIME)))) {
            return JSON.toJSONString("验证码已过期，请重试");
        }

        // 校验验证码
        String currentValidateCode = String.valueOf(request.getSession().getAttribute(VALIDATE_CODE));
        if (StringUtils.isEmpty(validateCode) || validateCode.length() != 4 ||
                !Utils.encodeBase64(validateCode).equals(currentValidateCode)) {
            return JSON.toJSONString("验证码错误");
        }
 }       

7 Base64加密

    public static String encodeBase64(String str) {
        sun.misc.BASE64Encoder base64Encode = new BASE64Encoder();
        return base64Encode.encode(str.getBytes());
    }