退出登录并实现过滤请求的三个示例

1.在登陆控制器存session值

2.做退出控制器

3.配置过滤器或者拦截器(防止不登录就能访问)

4.在过滤器@WebFilter或者拦截器过滤可以展现的页面;

过滤器示例一:前后端不分离,servlet+jsp,创建过滤器类,判断请求地址,包下有这么个过滤器类就可以了

 过滤器

package filter;

import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

public class LoginNecessary implements Filter {

    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
        
    }

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        HttpServletRequest httpServletRequest = (HttpServletRequest)servletRequest;
        HttpServletResponse httpServletResponse = (HttpServletResponse)servletResponse;
        String requestURI = httpServletRequest.getRequestURI();
        Object username = httpServletRequest.getSession().getAttribute("username");
        if (requestURI.endsWith("index.jsp")&&username==null){
        httpServletResponse.sendRedirect("login.jsp");
        }
        filterChain.doFilter(httpServletRequest,httpServletResponse);
    }

    @Override
    public void destroy() {

    }
}

示例二:前后端分离,控制器层请求地址*.do

 过滤器:包下有这么个过滤器类就可以了

package com.zhao.filter;

import com.zhao.utils.UserUtil;

import javax.servlet.*;
import javax.servlet.annotation.WebFilter;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

@WebFilter({"/admin/index.html","/admin/views/*"})
public class AccessFilter implements Filter {
    public void destroy() {
    }

    public void doFilter(ServletRequest req, ServletResponse resp, FilterChain chain) throws ServletException, IOException {
        HttpServletRequest request= (HttpServletRequest)req;
        HttpServletResponse response=(HttpServletResponse)resp;
        String adminName = UserUtil.getUserName(request.getSession());
        if(adminName!=null)
        chain.doFilter(req, resp);
        else
            ((HttpServletResponse) resp).sendError(404,"很抱歉,未登录权限不足");
    }

    public void init(FilterConfig config) throws ServletException {

    }

}

3.请求地址 / ,前后端分离,使用拦截器,需要有一个拦截器类,还需要在springmvc配置文件中配置拦截器

 拦截器:

package com.zhao.interceptor;

import com.zhao.pojo.Userh;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class LoginInterceptor implements HandlerInterceptor {
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        Userh user = (Userh) request.getSession().getAttribute("user");
        String uri = request.getRequestURI();
        String servletPath = request.getServletPath();
        //禁止浏览器使用缓存，防止退出登录后后退回页面
        response.setDateHeader("Expires", 0);
        response.setHeader("Cache-Control", "no-cache, no-store");
        response.setHeader("Pragma", "no-cache");


        if (user!=null||servletPath.contains("login")){
            return true;
        }
         response.sendRedirect("/login.html");
        return false;
    }

    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {

    }

    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {

    }
}

springmvc配置

   <!--配置拦截器-->
    <mvc:interceptors>
        <mvc:interceptor>
            <mvc:mapping path="/**.html" />   <!--拦截所有请求-->
            <bean class="com.zhao.interceptor.LoginInterceptor" id="loginInterceptor"></bean>
        </mvc:interceptor>
    </mvc:interceptors>