Java登录验证过滤器

一、配置文件web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://xmlns.jcp.org/xml/ns/javaee" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd" id="WebApp_ID" version="4.0">
  <display-name>lessons</display-name>
  <welcome-file-list>
    <welcome-file>index.jsp</welcome-file>
    <welcome-file>index.html</welcome-file>
  </welcome-file-list>
  
  <!-- 存储用户信息session的键 -->
  <context-param>
      <param-name>userSessionKey</param-name>
      <param-value>user</param-value>
  </context-param>
  
  <!-- 登录页面 -->
  <context-param>
      <param-name>loginPage</param-name>
      <param-value>/Login.jsp</param-value>
  </context-param>
  
  <filter>
      <filter-name>LoginFilter</filter-name>
      <filter-class>com.zyz.util.LoginFilter</filter-class>
  </filter>
  
  <!-- 对/admin/*的请求进行过滤  -->
  <filter-mapping>
      <filter-name>LoginFilter</filter-name>
      <url-pattern>/admin/*</url-pattern>
  </filter-mapping>
</web-app>

二、登录验证过滤器LoginFilter.java

package com.zyz.util;

import java.io.IOException;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.annotation.WebFilter;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.zyz.user.User;

@WebFilter("/LoginFilter")
public class LoginFilter implements Filter {
    private String userSessionKey;//存储用户的session键名
    private String loginPage;//登录页面
    
    public LoginFilter() {
    }

    public void destroy() {
    }

    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
        
        HttpServletRequest httpRequest=(HttpServletRequest)request;
        HttpServletResponse httpResponse=(HttpServletResponse)response;
        User user=(User)httpRequest.getSession().getAttribute(userSessionKey);
        
        //如果没有登录，或登录的用户角色不是管理员
        if(user==null || user.getRole()==0) {
            String servletPath=httpRequest.getServletPath();
            if(servletPath.endsWith(".jsp")) {
                //session记下当前请求的jsp文件的url，以便登录时跳转至该文件
                httpRequest.getSession().setAttribute("url",httpRequest.getContextPath()+servletPath);
            }
            //跳转到登录页面
            httpResponse.sendRedirect(httpRequest.getContextPath()+loginPage);
            return;
        }
        //如果已经登录，且是角色是管理员，放行。
        chain.doFilter(httpRequest, httpResponse);
    }

    public void init(FilterConfig fConfig) throws ServletException {
        ServletContext context=fConfig.getServletContext();
        userSessionKey=context.getInitParameter("userSessionKey");//从配置文件web.xml获取该参数
        loginPage=context.getInitParameter("loginPage");//从配置文件web.xml获取该参数
    }
}

三、登录处理LoginHandlerServlet.java

package com.zyz.user;

import java.io.IOException;
import java.util.Enumeration;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

@WebServlet("/LoginHandlerServlet")
public class LoginHandlerServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;
       
    public LoginHandlerServlet() {
        super();
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        this.doPost(request, response);
    }

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        response.setContentType("text/html;charset=UTF-8");
        String name = request.getParameter("name");
        String password = request.getParameter("password");
        if (name!=null && !name.equals("") && password!=null && !password.equals("")) {
            User u = UserService.getInstance().loginCheck(name, password);
            if (u == null) {
                response.getWriter().println("用户名或密码不对,3秒后将跳转<a href='Login.jsp'>登录</a>页面...");
                response.setHeader("refresh", "3;url=Login.jsp");
                return;
            } else {
                HttpSession session=request.getSession();
                
                //跳转前清空所有的session
                Enumeration<String> em=session.getAttributeNames();
                while(em.hasMoreElements()){
                    String attributeName=em.nextElement();
                    if(!attributeName.equals("url")) {
                        session.removeAttribute(attributeName);
                    }
                }
                
                session.setAttribute("user", u);
                
                String url;
                if(session.getAttribute("url")!=null){
                    url=session.getAttribute("url").toString();
                }else{
                    url="index.jsp";
                }
                response.sendRedirect(url);
            }
        }
    }

}

四、登录页面Login.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>

<%
    String name="";
    String password="";
    Cookie[] cookies=request.getCookies();
    for(Cookie c:cookies){
        if(c.getName().equals("name")){
            name=c.getValue();
        }
        if(c.getName().equals("password")){
            password=c.getValue();
        }
    }
%>

    
<!doctype html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>用户登录</title>
    <meta name="renderer" content="webkit|ie-comp|ie-stand">
    <meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1">
    <meta name="viewport" content="width=device-width,user-scalable=yes, minimum-scale=0.4, initial-scale=0.8,target-densitydpi=low-dpi" />
    <meta http-equiv="Cache-Control" content="no-siteapp" />

    <link rel="shortcut icon" href="/favicon.ico" type="image/x-icon" />
    <link rel="stylesheet" href="./admin/css/font.css">
    <link rel="stylesheet" href="./admin/css/xadmin.css">
    <script type="text/javascript" src="https://cdn.bootcss.com/jquery/3.2.1/jquery.min.js"></script>
    <script src="./lib/layui/layui.js" charset="utf-8"></script>
    <script type="text/javascript" src="./admin/js/xadmin.js"></script>

</head>
<body class="login-bg">
    
    <div class="login layui-anim layui-anim-up">
        <div class="message">用户登录</div>
        <div id="darkbannerwrap"></div>
        
        <form method="post" class="layui-form" action="LoginHandlerServlet">
            <input name="name" placeholder="用户名"  type="text" lay-verify="required|username" class="layui-input" value="<%= name %>" >
            <hr class="hr15">
            <input name="password" lay-verify="required|password" placeholder="密码"  type="password" class="layui-input" value=<%= password %>>
            <hr class="hr15">
            <input value="登录" lay-submit lay-filter="login" style="width:100%;" type="submit">
            <hr class="hr20" >
        </form>
    </div>

    <script>
        $(function  () {
            layui.use('form', function(){
              var form = layui.form;
              // layer.msg('玩命卖萌中', function(){
              //   //关闭后的操作
              //   });
              //监听提交
              /* form.on('submit(login)', function(data){
                // alert(888)
                layer.msg(JSON.stringify(data.field),function(){
                    location.href='index.html'
                });
                return false;
              });  */
              /* form.verify({
                  'username':[/\w{6,20}/,'用户名必须是6到20位字母、数字或下划线'],
                  'password':[/\w{6,12}/,'密码必须是6到12位字母、数字或下划线']
              }) */
            });
        })

        
    </script>
    <!-- 底部结束 -->
</body>
</html>