• 验证码采用一个博客上的验证码 点击跳转
• 采用action的形式获取验证码，并把验证码存入到shiro管理的session中

public void getGifCode(HttpServletResponse response,HttpServletRequest request){
    try {
        response.setHeader("Pragma", "No-cache");  
        response.setHeader("Cache-Control", "no-cache");  
        response.setDateHeader("Expires", 0);  
        response.setContentType("image/gif");  
        /**
         * gif格式动画验证码
         * 宽，高，位数。
         */
        Captcha captcha = new GifCaptcha(146,42,4);
        //输出
        ServletOutputStream out = response.getOutputStream();
        captcha.out(out);
        out.flush();
       //存入Shiro会话session  
        System.out.println( captcha.text().toLowerCase());
        TokenManager.setVal2Session(VerifyCodeUtils.V_CODE, captcha.text().toLowerCase());  
    } catch (Exception e) {
        LoggerUtils.fmtError(getClass(),e, "获取验证码异常：%s",e.getMessage());
    }
}

• 验证码验证的 Shiro 过滤器

public class JCaptchaValidateFilter extends AccessControlFilter{

    /**
     * 是否开启验证码验证   默认true
     */
    private boolean jcaptchaEbabled = true;

    /**
     * 前台提交的验证码参数名
     */
    private String jcaptchaParam = "jcaptchaCode";

    /**
     * 验证失败后存储到的属性名
     */
    private String failureKeyAttribute = "shiroLoginFailure";

    @Override
    protected boolean isAccessAllowed(ServletRequest request, ServletResponse response, Object o) throws Exception {
        //1、设置验证码是否开启属性，页面可以根据该属性来决定是否显示验证码
        request.setAttribute("jcaptchaEbabled", jcaptchaEbabled);

        HttpServletRequest httpRequest = WebUtils.toHttp(request);

        //2、判断验证码是否禁用 或不是表单提交（允许访问）
        if (jcaptchaEbabled == false || !"post".equalsIgnoreCase(httpRequest.getMethod())) {
            return true;
        }

        //表单提交，校验验证码的正确性
        String storedCode = getSubject(request, response).getSession().getAttribute(Constatns.VERIFYCODE).toString();
        String currentCode = httpRequest.getParameter(jcaptchaParam);

        return StringUtils.equalsIgnoreCase(storedCode, currentCode);
    }
    @Override
    protected boolean onAccessDenied(ServletRequest request, ServletResponse servletResponse) throws Exception {
        //如果验证码失败了，存储失败 key 属性
        request.setAttribute(failureKeyAttribute, "jCaptcha.error");
        return true;
    }
    public String getFailureKeyAttribute() {
        return failureKeyAttribute;
    }
    public void setFailureKeyAttribute(String failureKeyAttribute) {
        this.failureKeyAttribute = failureKeyAttribute;
    }
    public String getJcaptchaParam() {
        return jcaptchaParam;
    }
    public void setJcaptchaParam(String jcaptchaParam) {
        this.jcaptchaParam = jcaptchaParam;
    }
    public boolean isJcaptchaEbabled() {
        return jcaptchaEbabled;
    }
    public void setJcaptchaEbabled(boolean jcaptchaEbabled) {
        this.jcaptchaEbabled = jcaptchaEbabled;
    }
}

• MyFormAuthenticationFilter ，表单提交时，先验证验证码，如果验证成功再走登录流程

用于验证码验证的 Shiro 拦截器在用于身份认证的拦截器之前运行；但是如果验证码验证拦截器失败了，就不需要进行身份认证拦截器流程了；所以需要修改下如FormAuthenticationFilter 身份认证拦截器，当验证码验证失败时不再走身份认证拦截器。

public class MyFormAuthenticationFilter extends FormAuthenticationFilter {
    @Override
    protected boolean onAccessDenied(ServletRequest request, ServletResponse response) throws Exception {
        if(request.getAttribute(getFailureKeyAttribute()) != null) {
            return true;
        }
        return super.onAccessDenied(request, response);
    }
}

• 配置文件的配置

<!-- 基于form表单的身份验证过滤器 带有验证码的过滤-->
<bean id="myformAuthenticationFilter" class="com.nanc.core.shiro.filter.MyFormAuthenticationFilter">
    <property name="usernameParam" value="username"/>
    <property name="passwordParam" value="password"/>
    <property name="rememberMeParam" value="rememberMe"/>
    <property name="loginUrl" value="/login"/>
    <property name="failureKeyAttribute" value="shiroLoginFailure"/>
</bean>

<!-- 验证码的过滤器 -->
<bean id="jCaptchaFilter" class="com.nanc.core.shiro.filter.JCaptchaValidateFilter">
    <property name="failureKeyAttribute" value="shiroLoginFailure"/>
    <property name="jcaptchaParam" value="jcaptchaCode"/><!-- 页面的参数名-->
    <property name="jcaptchaEbabled" value="true"/>
</bean>

<!-- Shiro的Web过滤器 -->
<bean id="shiroFilter" class="org.apache.shiro.spring.web.ShiroFilterFactoryBean">
    <property name="securityManager" ref="securityManager"/>
    <property name="loginUrl" value="/login"/>
    <property name="filters">
        <map>
            <!--<entry key="authc" value-ref="formAuthenticationFilter"/>-->
            <entry key="authc" value-ref="myformAuthenticationFilter"/>
            <entry key="jcaptcha" value-ref="jCaptchaFilter"/>
            <entry key="sysUser" value-ref="sysUserFilter"/>
            <entry key="kickout" value-ref="kickoutFilter"/>
            <!--添加ssl支持-->
            <!--<entry key="ssl" value-ref="sslFilter"/>-->
            <!-- 结束ssl支持-->
        </map>
    </property>
    <property name="filterChainDefinitions">
        <value>
            /login=jcaptcha,authc
            /loginDialog=authc
            /logout=logout
            /authenticated=authc
            /dwz_jui/**=anon
            /common/**=anon
            /**=kickout,user,sysUser
        </value>
    </property>
</bean>