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一、Filter
1、介绍
- Filter（过滤器）是一个运行在服务器端，先于与之相关的Servlet或者Jsp页面之前运行，对请求资源进行过滤功能的技术
- Filter是JavaWEB三大组件(Servlet、Filter、 Listener)之一
2、编写流程
- 编写一个类实现javax.servlet.Filter接口
- 在web.xml中配置<filer>和<filter-mapping>配置项【快速创建方式不需要】
3、应用场景
- 自动登录
- 全站中文乱码处理
- 屏蔽非法字符
- 数据格式压缩
4、入门案例
package com.itheima.web.servlet;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class AServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// 处理post请求中文乱码问题
request.setCharacterEncoding("utf-8");
// 处理响应的中文乱码问题
response.setContentType("text/html;charset=utf-8");
System.out.println("已抵达目标资源...");
}
public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doGet(request, response);
}
}
package com.itheima.web.filter;
import java.io.IOException;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
public class AFilter implements Filter {
public void destroy() {
}
public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
throws IOException, ServletException {
System.out.println("进入过滤器了...");
// 放行
chain.doFilter(request, response);
}
public void init(FilterConfig fConfig) throws ServletException {
}
}
5、执行流程
二、案例：自动登录
1、自动登录需求分析
2、自动登录案例执行流程
登录页面
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<!doctype html>
<html>
<head>
<meta charset="utf-8" />
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>会员登录</title>
<link rel="stylesheet"
href="${pageContext.request.contextPath}/css/bootstrap.min.css"
type="text/css" />
<script src="${pageContext.request.contextPath}/js/jquery-1.11.3.min.js"
type="text/javascript"></script>
<script src="${pageContext.request.contextPath}/js/bootstrap.min.js"
type="text/javascript"></script>
<!-- 引入自定义css文件 style.css -->
<link rel="stylesheet"
href="${pageContext.request.contextPath}/css/style.css" type="text/css" />
<style>
body {
margin-top: 20px;
margin: 0 auto;
}
.carousel-inner .item img {
width: 100%;
height: 300px;
}
.container .row div {
/* position:relative;
float:left; */
}
font {
color: #666;
font-size: 22px;
font-weight: normal;
padding-right: 17px;
}
</style>
</head>
<body>
<!--
时间：2015-12-30
描述：菜单栏
-->
<div class="container-fluid">
<div class="col-md-4">
<img src="${pageContext.request.contextPath}/img/logo2.png" />
</div>
<div class="col-md-5">
<img src="${pageContext.request.contextPath}/img/header.png" />
</div>
<div class="col-md-3" style="padding-top: 20px">
<ol class="list-inline">
<li><a href="login.htm">登录</a></li>
<li><a href="register.htm">注册</a></li>
<li><a href="cart.htm">购物车</a></li>
</ol>
</div>
</div>
<!--
时间：2015-12-30
描述：导航条
-->
<div class="container-fluid">
<nav class="navbar navbar-inverse">
<div class="container-fluid">
<!-- Brand and toggle get grouped for better mobile display -->
<div class="navbar-header">
<button type="button" class="navbar-toggle collapsed"
data-toggle="collapse" data-target="#bs-example-navbar-collapse-1"
aria-expanded="false">
<span class="sr-only">Toggle navigation</span> <span
class="icon-bar"></span> <span class="icon-bar"></span> <span
class="icon-bar"></span>
</button>
<a class="navbar-brand" href="#">首页</a>
</div>
<!-- Collect the nav links, forms, and other content for toggling -->
<div class="collapse navbar-collapse"
id="bs-example-navbar-collapse-1">
<ul class="nav navbar-nav">
<li class="active"><a href="#">手机数码<span class="sr-only">(current)</span></a></li>
<li><a href="#">电脑办公</a></li>
<li><a href="#">电脑办公</a></li>
<li><a href="#">电脑办公</a></li>
</ul>
<form class="navbar-form navbar-right" role="search">
<div class="form-group">
<input type="text" class="form-control" placeholder="Search">
</div>
<button type="submit" class="btn btn-default">Submit</button>
</form>
</div>
<!-- /.navbar-collapse -->
</div>
<!-- /.container-fluid -->
</nav>
</div>
<div class="container"
style="width:100%;height:460px;background:#FF2C4C url('${pageContext.request.contextPath}/img/loginbg.jpg') no-repeat;">
<div class="row">
<div class="col-md-7">
<!--<img src="${pageContext.request.contextPath}/image/login.jpg" width="500" height="330" alt="会员登录" title="会员登录">-->
</div>
<div class="col-md-5">
<div
style="width: 440px; border: 1px solid #E7E7E7; padding: 20px 0 20px 30px; border-radius: 5px; margin-top: 60px; background: #fff;">
<font>会员登录</font>USER LOGIN
<div>
${msg }
</div>
<div> </div>
<%--登录表单start --%>
<form action="${pageContext.request.contextPath }/LoginServlet" method="post" class="form-horizontal">
<div class="form-group">
<label for="username" class="col-sm-2 control-label">用户名</label>
<div class="col-sm-6">
<input type="text" class="form-control" id="username" name="username"
placeholder="请输入用户名">
</div>
</div>
<div class="form-group">
<label for="password" class="col-sm-2 control-label">密码</label>
<div class="col-sm-6">
<input type="password" class="form-control" id="password" name="password"
placeholder="请输入密码">
</div>
</div>
<div class="form-group">
<label for="verifyCode" class="col-sm-2 control-label">验证码</label>
<div class="col-sm-3">
<input type="text" class="form-control" id="verifyCode" name="verifyCode"
placeholder="请输入验证码">
</div>
<div class="col-sm-3">
<img src="${pageContext.request.contextPath}/img/code.jpg" />
</div>
</div>
<div class="form-group">
<div class="col-sm-offset-2 col-sm-10">
<div class="checkbox">
<label>
<input type="checkbox" name="autoLogin"> 自动登录
</label>
<label>
<input type="checkbox" name="rememberme"> 记住用户名
</label>
</div>
</div>
</div>
<div class="form-group">
<div class="col-sm-offset-2 col-sm-10">
<input type="submit" width="100" value="登录"
style="background: url('${pageContext.request.contextPath}/img/login.gif') no-repeat scroll 0 0 rgba(0, 0, 0, 0);
height:35px;width:100px;color:white;">
</div>
</div>
</form>
<%--登录表单end --%>
</div>
</div>
</div>
</div>
<div style="margin-top: 50px;">
<img src="${pageContext.request.contextPath}/img/footer.jpg"
width="100%" height="78" alt="我们的优势" title="我们的优势" />
</div>
<div style="text-align: center; margin-top: 5px;">
<ul class="list-inline">
<li><a>关于我们</a></li>
<li><a>联系我们</a></li>
<li><a>招贤纳士</a></li>
<li><a>法律声明</a></li>
<li><a>友情链接</a></li>
<li><a target="_blank">支付方式</a></li>
<li><a target="_blank">配送方式</a></li>
<li><a>服务声明</a></li>
<li><a>广告声明</a></li>
</ul>
</div>
<div style="text-align: center; margin-top: 5px; margin-bottom: 20px;">
Copyright © 2005-2016 传智商城 版权所有</div>
</body>
</html>首页
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
<c:if test="${not empty existUser }">
你好,${existUser.username }
</c:if>
</body>
</html>自动登录过滤器
package com.itheima.web.filter;
import java.io.IOException;
import java.sql.SQLException;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import com.itheima.domain.User;
import com.itheima.service.UserService;
import com.itheima.utils.CookieUtils;
public class LoginFilter implements Filter {
public void destroy() {
}
public void doFilter(ServletRequest req, ServletResponse resp, FilterChain chain)
throws IOException, ServletException {
System.out.println("自动登录过滤器");
// 1.强转
HttpServletRequest request = (HttpServletRequest) req;
HttpServletResponse response = (HttpServletResponse) resp;
// 2.从session中获得用户信息
User sessionUser = (User) request.getSession().getAttribute("existUser");
// 3.判断
if (sessionUser != null) {
// 说明用户已经处于登录状态，不需要自动登录，放行
chain.doFilter(request, response);
// 不执行下面的代码
return;
}
/// **************用户处于未登录状态,判断用户是否需要自动登录
// 4.获得所有的Cookie
Cookie[] cookies = request.getCookies();
Cookie cookie = CookieUtils.getCookieByName(cookies, "autoLogin");
// 5.非空判断
if (cookie != null) {
// 说明需要自动登录，获得用户名和密码
String username = cookie.getValue().split(":")[0];
String password = cookie.getValue().split(":")[1];
// 创建User对象
User user = new User();
user.setUsername(username);
user.setPassword(password);
// 调用service层方法
UserService service = new UserService();
try {
User existUser = service.login(user);
// 判断
if (existUser != null) {
// 放行,让其进入目标资源
request.getSession().setAttribute("existUser", existUser);
chain.doFilter(request, response);
// 不让下面的代码执行
return;
}
} catch (Exception e) {
e.printStackTrace();
}
}
// 6.放行
chain.doFilter(request, response);
}
public void init(FilterConfig fConfig) throws ServletException {
}
}
LoginServlet
package com.itheima.web.servlet;
import java.io.IOException;
import java.lang.reflect.InvocationTargetException;
import javax.servlet.ServletException;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.apache.commons.beanutils.BeanUtils;
import com.itheima.domain.User;
import com.itheima.service.UserService;
/**
* 用户登录
*
*/
public class LoginServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// 处理post请求中文乱码问题
request.setCharacterEncoding("utf-8");
// 处理响应的中文乱码问题
response.setContentType("text/html;charset=utf-8");
// 1.创建一个user对象
User user = new User();
try {
BeanUtils.populate(user, request.getParameterMap());
UserService service = new UserService();
User existUser = service.login(user);
if (existUser != null) {
// 登录成功,判断用户是否勾选了自动登录的复选框
String autoLogin = request.getParameter("autoLogin");
if (autoLogin != null) {
// 说明用户已经勾选了自动登录复选框，将用户名和密码保存到Cookie（不要直接将user对象保存到cookie,cookie的数据可能被篡改！）
Cookie cookie = new Cookie("autoLogin", existUser.getUsername() + ":" + existUser.getPassword());
cookie.setPath("/");
cookie.setMaxAge(60 * 60 * 24 * 7);
response.addCookie(cookie);
}
// 将用户信息保存到域对象中
request.getSession().setAttribute("existUser", existUser);
//页面跳转
response.sendRedirect(request.getContextPath()+"/index.jsp");
} else {
// 说明登录失败,给出提示信息
request.setAttribute("msg", "<span style='color:red'>用户名或密码错误</span>");
//转发
request.getRequestDispatcher("login.jsp").forward(request, response);
}
} catch (Exception e) {
e.printStackTrace();
}
}
public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doGet(request, response);
}
}
package com.itheima.utils;
import javax.servlet.http.Cookie;
public class CookieUtils {
/**
* 获取指定名称的cookie
*/
public static Cookie getCookieByName(Cookie[] cookies, String cookieName) {
// 1.非空判断
if (cookies != null) {
// 2.遍历
for (Cookie cookie : cookies) {
// 3.判断
if (cookieName.equals(cookie.getName())) {
// 4.返回
return cookie;
}
}
}
return null;
}
}
service层
package com.itheima.service;
import java.sql.SQLException;
import com.itheima.dao.UserDao;
import com.itheima.domain.User;
public class UserService {
public User login(User user) throws SQLException {
UserDao dao = new UserDao();
return dao.login(user);
}
}
dao层
package com.itheima.dao;
import java.sql.SQLException;
import org.apache.commons.dbutils.QueryRunner;
import org.apache.commons.dbutils.handlers.BeanHandler;
import com.itheima.domain.User;
import com.itheima.utils.C3P0Utils;
public class UserDao {
public User login(User user) throws SQLException {
// 1.获得QueryRunner核心对象
QueryRunner qr = new QueryRunner(C3P0Utils.getDataSource());
// 2.编写SQL语句
String sql = "select * from user where username=? and password=?";
// 3.设置实际参数
Object[] params = {user.getUsername(),user.getPassword()};
// 4.执行查询操作
return qr.query(sql, new BeanHandler<>(User.class), params);
}
}
web.xml
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id="WebApp_ID" version="2.5">
<display-name>web_day40</display-name>
<welcome-file-list>
<welcome-file>index.html</welcome-file>
<welcome-file>index.htm</welcome-file>
<welcome-file>index.jsp</welcome-file>
<welcome-file>default.html</welcome-file>
<welcome-file>default.htm</welcome-file>
<welcome-file>default.jsp</welcome-file>
</welcome-file-list>
<servlet>
<description></description>
<display-name>AServlet</display-name>
<servlet-name>AServlet</servlet-name>
<servlet-class>com.itheima.web.servlet.AServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>AServlet</servlet-name>
<url-pattern>/AServlet</url-pattern>
</servlet-mapping>
<filter>
<display-name>AFilter</display-name>
<filter-name>AFilter</filter-name>
<filter-class>com.itheima.web.filter.AFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>AFilter</filter-name>
<url-pattern>/AServlet</url-pattern>
<dispatcher>REQUEST</dispatcher>
</filter-mapping>
<servlet>
<description></description>
<display-name>LoginServlet</display-name>
<servlet-name>LoginServlet</servlet-name>
<servlet-class>com.itheima.web.servlet.LoginServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>LoginServlet</servlet-name>
<url-pattern>/LoginServlet</url-pattern>
</servlet-mapping>
<filter>
<display-name>LoginFilter</display-name>
<filter-name>LoginFilter</filter-name>
<filter-class>com.itheima.web.filter.LoginFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>LoginFilter</filter-name>
<url-pattern>/*</url-pattern>
<dispatcher>REQUEST</dispatcher>
</filter-mapping>
</web-app>