过滤器(Filter)应用之------设置页面缓存、用户的自动登录和敏感词过滤
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PPT先贴一下,供以后查看。
Filter的应用
-1:
1、设置所有jsp页面不缓存:开发步骤:1、书写一个Filter,在其doFilter方法中添加以下代码:HttpServletResponse resp = (HttpServletResponse)response;resp.setHeader("expires","-1");resp.setHeader("pragma", "no-cache");resp.setHeader("cache-control","no-cache");chain.doFilter(request, resp);//注意是已经强转了的对像2、将Filter配置到web.xml中。配置如下:<filter><filter-name>jspcache</filter-name><filter-class>cn.itcast.filter.JspPageFilter</filter-class> </filter> <filter-mapping> <filter-name>jspcache</filter-name> <url-pattern>*.jsp</url-pattern> </filter-mapping>3、打开ie,清空所有Cookie的临时文件。4、访问本项目的jsp页面,看缓存中是否有临时文件。5、将Filter的配置删除,然后再去看是否会出现临时文件。
-2:
设置某些静态的页面如html或jpg缓存。设置url-pattern为*.html和*.jpg。开发步骤:1、书写一个过虑器,在doFilter中的代码如下:HttpServletResponse response2 = (HttpServletResponse)response;Calendar c = Calendar.getInstance();c.add(Calendar.DATE,4);//缓存到当前天以后的4天long lon = c.getTimeInMillis();//获取时间的毫秒response2.setDateHeader("expires",lon);//setDateHeader是设置时间头chain.doFilter(request, response2);2、将过虑器配置到web.xml中,如下:<filter-mapping> <filter-name>cache</filter-name> <!-- 配置只能jpg文件缓存 --> <url-pattern>*.jpg</url-pattern></filter-mapping>3、请求资源,再次请求。查看状态码为304,及缓存文件的日期为N天以后。这是返回的状态码:HTTP/1.1 304 Not Modified
-3:
实现用户的自动登录:
•解决方案:
•设置一个全站拦截的过虑器。
•在此过虑器中,读取用户带过来的Cookie信息,然后从中读取用户的用户名和密码,自动帮助用户登录。
•即可实现自动登录功能。
canAutoLogingFilterWeb项目
当用户登录的时候可以选择自动登录多久,保存到Session和Cookie中,用过滤器来查找Cookie,进行验证,帮助用户自动登录。
index.jsp
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%><%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html> <head> <body> <c:if test="${!empty sessionScope.error }" > 登录失败,用户名或密码错误! <!-- 错误信息用完一次就要清掉 --> <c:remove var="error" scope="session"/> </c:if> <c:if test="${empty sessionScope.user }" var="boo"> <form action="<c:url value='/LoginServlet' />" method="post"> 姓名:<input type="text" name="name"><br/> 密码:<input type="text" name="pwd"><br/> <fieldset style="width:200px"> <legend>自动登录</legend> <input type="radio" name="time" value="0" checked="checked">不自动登录<br/><br/> <input type="radio" name="time" value="1">一天自动登录<br/><br/> <input type="radio" name="time" value="7">一周自动登录<br/><br/> <input type="submit" value="登录"> </fieldset> </form> </c:if> <c:if test="${!boo }"> 欢迎您,${user}! <a href="<c:url value='/jsps/show.jsp' />">信息浏览</a> <a href="<c:url value='/LoginServletCancel' />">退出</a> </c:if> </body></html>
登录验证的LoginServlet.java
package cn.hncu.servlets;import java.io.IOException;import java.net.URLEncoder;import javax.servlet.ServletException;import javax.servlet.http.Cookie;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;public class LoginServlet extends HttpServlet {public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {doPost(request, response);}public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException { if(request.getSession().getAttribute("user")!=null){ /* * 这里补一个bug,如果登录以后,退回到登录页面,再登录一个账号,如登录失败,但另外一个账号还是在登录 * 应该在登录之前,把原先的登录数据清除掉 */ request.getSession().removeAttribute("user"); Cookie cookie=new Cookie("autoLogin",""); cookie.setMaxAge(0); cookie.setPath(request.getContextPath()); response.addCookie(cookie); }String name =request.getParameter("name");String pwd =request.getParameter("pwd");//本例中省去后台数据库验证,直接以name是hncu和密码长度大于6位来判断,模拟一下if(name.startsWith("hncu") && pwd.length()>=6){request.getSession().setAttribute("user", name);//下面这段专用于自动登录(把用户名和密码封装到cookie中并写到客户端浏览器中)//为安全考虑,这里密码应该进行加密且根据安全级别进行二次加密,还可以考虑捆绑ip或机器系统信息加密//为使cookie能够存储中文信息,则需把信息进行编码name=URLEncoder.encode(name, "utf-8");pwd=URLEncoder.encode(pwd, "utf-8");Cookie cookie=new Cookie("autoLogin", name+","+pwd);cookie.setPath(request.getContextPath());//cookie的作用域是这个项目String time=request.getParameter("time");Integer iTime=Integer.valueOf(time);iTime=iTime*60*60*24;//cookie默认是秒cookie.setMaxAge(iTime);response.addCookie(cookie);}else{request.getSession().setAttribute("error", "1");//登录失败}response.sendRedirect(request.getContextPath()+"/index.jsp");}}
三个过滤器
字符编码过滤器CharacterFilter.java
package cn.hncu.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 CharacterFilter implements Filter{private String charset;@Overridepublic void init(FilterConfig config) throws ServletException {charset=config.getInitParameter("charset");}@Overridepublic void doFilter(ServletRequest request, ServletResponse response,FilterChain chain) throws IOException, ServletException {request.setCharacterEncoding(charset);response.setContentType("text/html;charset=utf-8");chain.doFilter(request, response);}@Overridepublic void destroy() {}}
黑名单过滤器BlackListFilter.java
package cn.hncu.filter;import java.io.IOException;import java.util.HashSet;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 BlackListFilter implements Filter{private HashSet<String> set=new HashSet<String>();@Overridepublic void init(FilterConfig filterConfig) throws ServletException {//黑名单初始化//set.add("127.0.0.1");//set.add("10.31.1.212");}@Overridepublic void doFilter(ServletRequest request, ServletResponse response,FilterChain chain) throws IOException, ServletException {String addr=request.getRemoteAddr();System.out.println(addr);if(set.contains(addr)){response.getWriter().println("你已被拉入黑名单,不能登录");}else{chain.doFilter(request, response);}}@Overridepublic void destroy() {}}
自动登录过滤器AutoLoginFilter.java
package cn.hncu.filter;import java.io.IOException;import java.net.URLDecoder;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;public class AutoLoginFilter implements Filter{@Overridepublic void init(FilterConfig filterConfig) throws ServletException {}@Overridepublic void doFilter(ServletRequest request, ServletResponse response,FilterChain chain) throws IOException, ServletException {HttpServletRequest req=(HttpServletRequest) request;if(req.getSession().getAttribute("user")==null){//没有登录//没有登录就查找cookie----autoLogin,若有则帮助登录(验证及往session中放信息),若没有则登录失败,踢回到登录界面;Cookie cookies[]=req.getCookies();if(cookies!=null){//这里也要防护一下,防止cookies为空for(Cookie cookie:cookies){//遍历cookie寻找名为autoLogin的cookieif(cookie.getName().equals("autoLogin")){String[] values=cookie.getValue().split(",");//拆分出来String name=values[0];String pwd=values[1];//由于用户名和密码是经过编码的,所以这里要进行解码name=URLDecoder.decode(name,"utf-8");pwd=URLDecoder.decode(pwd, "utf-8");//这里应该到后台数据库中验证一下,此处省略了if(name.startsWith("hncu")&&pwd.length()>=6){req.getSession().setAttribute("user", name);}break;}}}}chain.doFilter(request, response);}@Overridepublic void destroy() {}}
web.xml的配置
<?xml version="1.0" encoding="UTF-8"?><web-app version="3.0" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"> <display-name></display-name> <filter> <filter-name>charset</filter-name> <filter-class>cn.hncu.filter.CharacterFilter</filter-class> <init-param> <param-name>charset</param-name> <param-value>utf-8</param-value> </init-param> </filter> <filter> <filter-name>BlackListFilter</filter-name> <filter-class>cn.hncu.filter.BlackListFilter</filter-class> </filter> <filter> <filter-name>AutoLoginFilter</filter-name> <filter-class>cn.hncu.filter.AutoLoginFilter</filter-class> </filter> <servlet> <servlet-name>LoginServlet</servlet-name> <servlet-class>cn.hncu.servlets.LoginServlet</servlet-class> </servlet> <servlet> <servlet-name>LoginServletCancel</servlet-name> <servlet-class>cn.hncu.servlets.LoginServletCancel</servlet-class> </servlet><filter-mapping><filter-name>charset</filter-name><url-pattern>/*</url-pattern></filter-mapping><filter-mapping><filter-name>BlackListFilter</filter-name><url-pattern>/*</url-pattern></filter-mapping><filter-mapping><filter-name>AutoLoginFilter</filter-name><url-pattern>/*</url-pattern></filter-mapping> <servlet-mapping> <servlet-name>LoginServlet</servlet-name> <url-pattern>/LoginServlet</url-pattern> </servlet-mapping> <servlet-mapping> <servlet-name>LoginServletCancel</servlet-name> <url-pattern>/LoginServletCancel</url-pattern> </servlet-mapping> <welcome-file-list> <welcome-file>index.jsp</welcome-file> </welcome-file-list></web-app>
取消自动登录的LoginServletCancel.java
package cn.hncu.servlets;import java.io.IOException;import javax.servlet.ServletException;import javax.servlet.http.Cookie;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;public class LoginServletCancel extends HttpServlet {public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {doPost(request, response);}public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {/*取消自动登录 * 1.session * 2.cookie */request.getSession().setAttribute("user", null);Cookie cookie=new Cookie("autoLogin","");cookie.setMaxAge(0);cookie.setPath(request.getContextPath());response.addCookie(cookie);response.sendRedirect(request.getContextPath()+"/index.jsp");}}
一个没什么用的显示show.jsp
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%><%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html> <head> <body> <c:if test="${!empty sessionScope.error }" > 登录失败,用户名或密码错误! <!-- 错误信息用完一次就要清掉 --> <c:remove var="error" scope="session"/> </c:if> <c:if test="${empty sessionScope.user }" var="boo"> 啦啦啦啦啦了 </c:if> </body></html>
主页图:
登录成功图:登录成功以后,如选择了自动登录时间,则再次登录就不用输入登录信息
登录失败:
这里用的是直接把电脑ip加入黑名单:
PPT突然又出来一个包装设计模式,还是贴一下吧。
包装设计模式:
对一个类的增强,一般采取三种式
•1、继承被增强的类,即实现一个子类。
•2、使用动态代理处理需要增强的方法。
•3、使用包装设计模式。(Java中的IO基本上都是包装设计模式)
以下是使用包装设计模式增强一个类的步骤:
•1、继承需要增强的类。
•2、声明需要增强有的类为自己的成员变量。
•3、书写一个构造方法接收需要增强的类。
•4、实现需要增强的方法。
•5、实现可扩展的其他方法。
包装设计模式是指:
•假定A类是B类的包装类,那么类A与类B有同样的接口,并且类A拥有类B的的实例,类A借助类B的实例来实现接口。
-6:
过虑非法语句,如脏话,和非法词组。
•解决方案:
•在过虑器中。包装httpServletRequest类,修改getParameter方法。即可。
canWordsFilterWeb
敏感词过滤:用过滤器(包装模式)偷偷把request的getParameter方法增强一下,把敏感词过滤掉
index.jsp
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%><%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html> <head> </head> <body > <div align="center"> <h2>用户留言板</h2> <form action="<c:url value='/NoteServlet' />" method="post"> 用户名<input type="text" name="name" /><br/> <textarea rows="20" cols="40" name="info"></textarea><br/> <input type="submit" value="留言" /> </form> </div> <a href="<c:url value='/jsps/addWord.jsp'/> ">管理员添加敏感词库入口</a> </body></html>
请求后台的时候被过滤器拦住WordFilter.java
package cn.hncu.filter;import java.io.IOException;import java.util.List;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.HttpServletRequest;import javax.servlet.http.HttpServletRequestWrapper;import cn.hncu.pubs.WordUtils;public class WordFilter implements Filter{@Overridepublic void init(FilterConfig filterConfig) throws ServletException {}@Overridepublic void doFilter(ServletRequest request, ServletResponse response,FilterChain chain) throws IOException, ServletException {//用包装模式增强requset的功能request.setCharacterEncoding("utf-8");MyRequest req =new MyRequest((HttpServletRequest) request);chain.doFilter(req, response);}@Overridepublic void destroy() {}}class MyRequest extends HttpServletRequestWrapper{private HttpServletRequest request;public MyRequest(HttpServletRequest request) {super(request);this.request=request;}@Overridepublic String getParameter(String name) {//先用原装的方法把原始信息读取出来String info=super.getParameter(name);List<String> words=WordUtils.getWords();for(String word:words){if(info.contains(word)){String rpWord="";for(int i=0;i<word.length();i++){rpWord+="*";}info=info.replaceAll(word,rpWord);}}System.out.println(info);return info;}}
内存存放敏感词工具类WordUtils.java
package cn.hncu.pubs;import java.util.ArrayList;import java.util.List;public class WordUtils {//建一个敏感词库private static List<String> list=new ArrayList<String>();public static List<String> getWords(){return list;}//给管理员提供加载词库的方法public static void rbWords(){//这里应该把数据库中的所有信息加载进来,这里模拟一下list.add("sb");list.add("你是一条小狗");}//给管理员在线、实时添加敏感词提供的方法public static void addWord(String word){list.add(word);}}
web.xml的配置
<?xml version="1.0" encoding="UTF-8"?><web-app version="3.0" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"> <display-name></display-name> <filter> <filter-name>WordFilter</filter-name> <filter-class>cn.hncu.filter.WordFilter</filter-class> </filter> <servlet> <servlet-name>NoteServlet</servlet-name> <servlet-class>cn.hncu.servlets.NoteServlet</servlet-class> </servlet> <servlet> <servlet-name>AdminWordsServlet</servlet-name> <servlet-class>cn.hncu.servlets.AdminWordsServlet</servlet-class> </servlet><filter-mapping><filter-name>WordFilter</filter-name><url-pattern>/*</url-pattern></filter-mapping> <servlet-mapping> <servlet-name>NoteServlet</servlet-name> <url-pattern>/NoteServlet</url-pattern> </servlet-mapping> <servlet-mapping> <servlet-name>AdminWordsServlet</servlet-name> <url-pattern>/AdminWordsServlet</url-pattern> </servlet-mapping> <welcome-file-list> <welcome-file>index.jsp</welcome-file> </welcome-file-list></web-app>
服务器NoteServlet.java
package cn.hncu.servlets;import java.io.IOException;import java.io.PrintWriter;import java.text.SimpleDateFormat;import java.util.Date;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;public class NoteServlet extends HttpServlet {public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {doPost(request, response);}public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {response.setContentType("text/html;charset=utf-8");PrintWriter out = response.getWriter();out.println("<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\">");out.println("<HTML>");out.println(" <HEAD><TITLE>A Servlet</TITLE></HEAD>");out.println(" <BODY>");String addr=request.getRemoteAddr();SimpleDateFormat sdf=new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");String time=sdf.format(new Date());String user=request.getParameter("name");String info=request.getParameter("info");out.println(time+" "+addr+"----"+user+"说: "+info);out.println(" </BODY>");out.println("</HTML>");out.flush();out.close();}}
管理员添加敏感词界面addWord.jsp
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%><%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html> <head> </head> <body > <c:if test="${!empty acc }" var="acc" scope="session"> 添加成功! <c:remove var="acc" scope="session"/> </c:if> <div align="center"> <h2>增加词库界面</h2> <form action="<c:url value='/AdminWordsServlet' />" method="post"> 敏感词<input type="text" name="word" /><br/> <input type="submit" value="保存" /> </form> </div> </body></html>
AdminWordsServlet.java
package cn.hncu.servlets;import java.io.IOException;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import cn.hncu.pubs.WordUtils;public class AdminWordsServlet extends HttpServlet {public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {doPost(request, response);}public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {request.setCharacterEncoding("utf-8");WordUtils.addWord(request.getParameter("word"));request.getSession().setAttribute("acc", 1);response.sendRedirect(request.getContextPath()+"/jsps/addWord.jsp");}}
主页图:
管理员添加敏感词:
用户留言:
1 0
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