狂神说Java【SMBMS】——SMBMS超市订单管理系统(三) ——登陆功能优化

本文主要是介绍狂神说Java【SMBMS】——SMBMS超市订单管理系统(三) ——登陆功能优化，对大家解决编程问题具有一定的参考价值，需要的程序猿们随着小编来一起学习吧！

1、注销功能

思路：移除session对象+返回登陆页面

1.编写servlet

package com.thhh.servlet.user;

import com.thhh.utils.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 {
        req.getSession().removeAttribute(Constants.USER_SESSION);//移除用户session
        resp.sendRedirect(req.getContextPath()+"/login.jsp");//重定向回登陆页面
    }

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

2.注册servlet

<!--注册注销servlet-->
<servlet>
    <servlet-name>LogoutServlet</servlet-name>
    <servlet-class>com.thhh.servlet.user.LogoutServlet</servlet-class>
</servlet>
<servlet-mapping>
    <servlet-name>LogoutServlet</servlet-name>
    <url-pattern>/jsp/logout.do</url-pattern>
</servlet-mapping>

2、登陆拦截优化

1.编写过滤器

package com.thhh.filter;

import com.thhh.pojo.User;
import com.thhh.utils.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 chain) throws IOException, ServletException {
        HttpServletRequest request = (HttpServletRequest)req;//父类强转子类,用于获取session
        HttpServletResponse response = (HttpServletResponse) resp;//父类强转子类，用于重定向
        User user = (User) request.getSession().getAttribute(Constants.USER_SESSION);

        if (user==null){//用户处于未登陆状态
            response.sendRedirect(request.getContextPath()+"/error.jsp");//重定向到登陆页面
        }else{
            chain.doFilter(req,resp);//过滤器放行
        }
    }

    @Override
    public void destroy() {

    }
}

2.注册过滤器

<!--注册未登录时请求后台页面过滤器-->
<filter>
    <filter-name>SysFilter</filter-name>
    <filter-class>com.thhh.filter.SysFilter</filter-class>
</filter>
<filter-mapping>
    <filter-name>SysFilter</filter-name>
    <url-pattern>/jsp/*</url-pattern>
    <!--注意：我们将所有需要登陆之后才能访问的功能性页面给都放在了/jsp文件夹下，所以过滤器应该过滤这个文件夹下的请求-->
</filter-mapping>

3.导入error页面