超市订单管理系统（4）-用户注销和权限拦截

1.注销功能：移除session，返回登录页面即可

　　（1）编写移除注销功能的servlet

package com.xiaoma.servlet.user;

import com.xiaoma.util.Constants;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

public class LogoutServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //移除session
        req.getSession().removeAttribute(Constants.USER_SESSION);
        //重定向到登录页面
        resp.sendRedirect(req.getContextPath()+"/login.jsp");
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doGet(req, resp);
    }
}

　　（2）在web.xml中注册我们的servlet，注意这里的url-patten是走的前端的jsp/common/head.jsp下的退出走的那个url

 

 

 

 

 

 

 

 

 

 

 

　　　　　　　　　　　　　　　　　　　　　

　　（3）效果图

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2. 登录权限拦截

 　　（1）在filter文件夹下创建一个SysFilter类文件，用来进行登录拦截，所需的error.jsp页面链接：https://pan.baidu.com/s/1UKtUbRBphFyIlk6RU9aR9g提取码：5210

package com.xiaoma.filter;

import com.xiaoma.pojo.User;
import com.xiaoma.util.Constants;

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


public class SysFilter implements Filter {

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

    }

    @Override
    public void doFilter(ServletRequest req, ServletResponse resp, FilterChain filterChain) throws IOException, ServletException {
        //request用来获取session，request用来重定向
        HttpServletRequest request=(HttpServletRequest) req;
        HttpServletResponse response=(HttpServletResponse) resp;

        //获取session
        User user=(User) request.getSession().getAttribute(Constants.USER_SESSION);

        //用户session为空，就说明用户已经注销了，或者未登录
        if (user == null) {
            response.sendRedirect(((HttpServletRequest) req).getContextPath()+"/error.jsp");
        }else{
            filterChain.doFilter(req,resp);
        }
    }

    @Override
    public void destroy() {

    }
}

　　（2）在web.xml中注册过滤器

    <!--注册权限拦截过滤器-->
    <filter>
        <filter-name>SysFilter</filter-name>
        <filter-class>com.xiaoma.filter.SysFilter</filter-class>
    </filter>
    <filter-mapping>
        <filter-name>SysFilter</filter-name>
        <url-pattern>/jsp/*</url-pattern>
    </filter-mapping>

　　（3）运行测试效果