springMVC集成shiro权限认证框架，登录之后退出登录出现登录不上的问题

有两种解决方式：

1.在web.xml文件配置一段欢迎页面：

<welcome-file-list>
    <welcome-file>/index.do</welcome-file>     
 </welcome-file-list>

 2.在自定义表单过滤器MyFormAuthenticationFilter里，添加清除shiro 在sesion存储的上一次访问地址 shiroSavedReques 

package cn.zj.logistic.shiro;

import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;

import org.apache.commons.lang3.StringUtils;
import org.apache.shiro.authc.AuthenticationToken;
import org.apache.shiro.session.Session;
import org.apache.shiro.subject.Subject;
import org.apache.shiro.web.filter.authc.FormAuthenticationFilter;
import org.apache.shiro.web.util.WebUtils;

public class MyFormAuthenticationFilter extends FormAuthenticationFilter {

    @Override
    protected boolean onAccessDenied(ServletRequest request, ServletResponse response) throws Exception {

        HttpServletRequest req = (HttpServletRequest) request;

        // 1.获取前台表单提交的验证码
        String verifyCode = req.getParameter("verifyCode");

        
        
        String rand = (String) req.getSession().getAttribute("rand");

        System.out.println("rand :" + rand);

        if (StringUtils.isNotBlank(verifyCode)) {
            if (!verifyCode.equals(rand.toLowerCase())) {
                // 共享一个错误信息到 shiroLoginFailure
                request.setAttribute("shiroLoginFailure", "verifyCodeError");

                // 返回true，shiro就不再进行下一操作（数据库认证）了，直接返回了
                return true;
            }
        }

        return super.onAccessDenied(request, response);
    }

    @Override
    protected boolean onLoginSuccess(AuthenticationToken token, Subject subject, ServletRequest request,
            ServletResponse response) throws Exception {
                
    
        // 1.获取sesssion
        Session session = subject.getSession(false);
        if (session != null) {
            // 清除shiro共享的上一次地址 ://shiroSavedRequest
            session.removeAttribute(WebUtils.SAVED_REQUEST_KEY);
        }

        return super.onLoginSuccess(token, subject, request, response);
    }

}