过滤器实栗 登录检测
项目结构  代码如下 登录servlet package com.ming.servlrt; import com.ming.factory.DAOFactory; import com.ming.vo.User; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import javax.servlet.http.HttpSession; import java.io.IOException; import java.util.ArrayList; import java.util.List; public class LoginServlet extends HttpServlet { @Override protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { String path = "login.jsp"; // 接收userid内容 String userid = req.getParameter("userid"); // 接收userpass内容 String userpadd = req.getParameter("userpass"); // 保存返回信息 List<String> info = new ArrayList<String>(); if(userid == null || "".equals(userid)){ info.add("用户id不能为空"); } if(userpadd == null || "".equals(userpadd)){ info.add("密码不能为空"); } // 报错信息为0进行验证 if(info.size() == 0){ User user = new User(); user.setUserid(userid); user.setPassword(userpadd); try{ if(DAOFactory.getIuserDAOInstance().findLogin(user)){ info.add("登录成功!" + user.getName()); // 增加session会话 HttpSession session = req.getSession(); session.setAttribute("id", userid); }else{ info.add("登录失败"); } }catch (Exception e){ e.printStackTrace(); } } // 使用服务器端跳转, 保存数据 req.setAttribute("info", info); req.getRequestDispatcher(path).forward(req, resp); } @Override protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { this.doGet(req, resp); } } 对于登录的servlet增加了session 过滤器如下 package com.ming.filter; import javax.servlet.*; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpSession; import java.io.IOException; // 首页过滤器 public class LoginFile implements Filter { @Override public void init(FilterConfig filterConfig) throws ServletException { } @Override public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException { // 转型 因为默认的ServletRequest中未提供相关的方法,需要向下转型 HttpServletRequest request = (HttpServletRequest)servletRequest; // 获取到session HttpSession session = request.getSession(); // 判断登录 if(session.getAttribute("id") != null){ // 已经登录 filterChain.doFilter(servletRequest, servletResponse); }else{ // 跳转登录页登录 request.getRequestDispatcher("login.jsp").forward(servletRequest, servletResponse); } } @Override public void destroy() { } } 配置文件如下 <!DOCTYPE web-app PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN" "http://java.sun.com/dtd/web-app_2_3.dtd" > <web-app> <display-name>Archetype Created Web Application</display-name> <filter> <filter-name>LoginFile</filter-name> <filter-class>com.ming.filter.LoginFile</filter-class> </filter> <filter-mapping> <filter-name>LoginFile</filter-name> <url-pattern>/index.jsp</url-pattern> </filter-mapping> <servlet> <servlet-name>login</servlet-name> <servlet-class>com.ming.servlrt.LoginServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>login</servlet-name> <url-pattern>/loginServlet</url-pattern> </servlet-mapping> </web-app> jsp文件如下 涉及 前端的js验证采用拦截click事件 <%@ page import="java.util.List" %> <%@ page import="java.util.Iterator" %><%-- Created by IntelliJ IDEA. User: ming Date: 19-3-16 Time: 下午11:07 To change this template use File | Settings | File Templates. --%> <%@ page contentType="text/html;charset=UTF-8" language="java" %> <html> <head> <title>Title</title> </head> <body> <h2>用户登录程序</h2> <% List<String> info = (List<String>)request.getAttribute("info"); if(info != null){ Iterator<String> iterator = info.iterator(); while(iterator.hasNext()){ %> <h4><%=iterator.next()%></h4> <% } } %> <form action="loginServlet" method="post"> 用户id <input type="text" name="userid" id="uname"/> 密码 <input type="password" name="userpass" id="password"/> <input type="submit" value="登录" id="submit"/> <input type="reset" value="重置"/> </form> <script> let submit = document.getElementById("submit"); submit.onclick = (event) => { let uname = document.getElementById("uname").value; let password = document.getElementById("password").value; if(!(/^\w{1,15}/.test(uname))){ alert("用户id为5-15位"); return false; } if(!(/^\w{1,15}/.test(password))){ alert("密码必须为5-15位"); return false; } return true; } </script> </body> </html>
