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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

2016-12-02 20:07 726 查看

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;
@Override
public void init(FilterConfig config) throws ServletException {
charset=config.getInitParameter("charset");
}

@Override
public 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);
}

@Override
public 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>();
@Override
public void init(FilterConfig filterConfig) throws ServletException {
//黑名单初始化
//		set.add("127.0.0.1");
//		set.add("10.31.1.212");
}

@Override
public 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);
}
}

@Override
public 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{

@Override
public void init(FilterConfig filterConfig) throws ServletException {
}

@Override
public 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cookie
if(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);
}

@Override
public 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{

@Override
public void init(FilterConfig filterConfig) throws ServletException {
}

@Override
public 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);
}

@Override
public void destroy() {
}

}
class MyRequest extends HttpServletRequestWrapper{
private HttpServletRequest request;
public MyRequest(HttpServletRequest request) {
super(request);
this.request=request;
}
@Override
public 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：

内容来自用户分享和网络整理，不保证内容的准确性，如有侵权内容，可联系管理员处理

标签： filter 自动登录过滤器黑名单 JavaWeb

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