JavaWeb-19 (JDBC之过滤器Filter)
2015-04-02 18:24
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JavaWeb-19
JDBC之过滤器Filter
一、Filter过滤器概述
Filter（过滤器）：Web三大组件之一，就是对目标资源进行请求前或请求后.Filter也称之为过滤器，它是Servlet技术中最激动人心的技术，WEB开发人员通过Filter技术，对web服务器管理的所有web资源：例如Jsp, Servlet, 静态图片文件或静态 html 文件等进行拦截，从而实现一些特殊的功能。例如实现URL级别的权限访问控制、过滤敏感词汇、压缩响应信息等一些高级功能。
实际中：过滤器就相当于山大王，作用就是拦截，拦截不拦截，山大王说的算
查看java Servlet文档去查看Filter解释
作用？ 实例： 1、动态资源不缓存 2、静态资源缓存 3、中文乱码集中处理 4、特殊字符过滤 5、全站压缩（选做） 6、脚本过滤
写法？
1、写类：
类 implements Filter init(FilterConfig) doFilter(ServletRequest,ServletResponse,FilterChain) destory() 在其他里寻找Filter类型的文件来新建，因为这样web.xml可以自动配置，和Servlet一样。 在新建栏里有初始化参数栏（encoding：UTF-8） 还有一个映射栏(filter mappings: /*:代表过滤所有资源)，或者在里面写具体的资源，那么就只拦截具体的资源 配置web.xml：由于在新建选择了新建Filter类型的文件，MyEclipse会自动配置web.xml 在服务器启动时，filter已经实例化了，证明filter的生命周期比servlet长，不要直接访问过滤器。 在IE里尝试访问index.jsp 通过web.xml里的设置，会在访问index.jsp里导致filter里的方法执行。
2、在web.xml中进行配置.
格式！！
3、对于Filter中的doFilter与FilterChain中的doFilter的比较？
a、个数不同 Filter接口doFilter是3个参数ServletRequset,ServletResponse,FilterChain FilterChain参数2个：ServletRequset,ServletResponse b、作用不同 Filter接口doFilter拦截作用 FilterChain接口中的doFilter起放行作用。
二、Filter过滤器链执行顺序
1、过滤器一般就是起拦截作用的，不要直接访问过滤器2、生命周期
1、容器启动时，Filter就会进行实例化（构造方法），初始化（init）--->只有一次机会 2、以后每次访问目标资源时，在符合条件的情况下，过滤器执行doFilter（）进行拦截。 3、当应用被卸载或服务停止时，destory（）被执行---->只有一次机会
3、拦截的顺序问题？
有多个过滤器就会形成一个（过滤器链），先执行第一个过滤器，再执行第二个过滤器 顺序取决于在web.xml中配置的顺序，看filter-mapping先后顺序，filter-mapping前先过滤。 <filter-mapping> <filter-name>CharacterEncodingFilter</filter-name> <url-pattern>/a</url-pattern> </filter-mapping> <filter-mapping> <filter-name>DirtyWordsFilter</filter-name> <url-pattern>/b</url-pattern> </filter-mapping> <filter-mapping> <filter-name>HtmlFilter</filter-name> <url-pattern>/c</url-pattern> </filter-mapping> <filter-mapping> <filter-name>GzipFilter</filter-name> <url-pattern>/d</url-pattern> </filter-mapping>
比如上面的web.xml配置文件所配置的Filter执行顺序是：CharacterEncodingFilter-->DirtyWordsFilter-->HtmlFilter-->GzipFilter
三、获取初始化参数
1、配置时1、/路径名/* (/*) 2、*.扩展名 (*.jsp) 3、具体路径 (/add.jsp)
2、一个过滤器可以有多个过滤路径
<filter-mapping> <filter-name>filterDemo1</filter-name> <url-pattern>/add.jsp</url-pattern> </filter-mapping> <filter-mapping> <filter-name>filterDemo1</filter-name> <url-pattern>/login.jsp</url-pattern> </filter-mapping>
3、对于初始化参数的配置及读取(FliterConfig)
/*
<init-param>
<param-name>encoding</param-name>
<param-value>GBK</param-value>
</init-param>
*/
//得到一个参数
/*String value = config.getInitParameter("encoding");
System.out.println(value);
chain.doFilter(request, response);*/
//得到多个参数
Enumeration<String> enums = config.getInitParameterNames();
while(enums.hasMoreElements()){
String paramName = enums.nextElement();
String paramValue = config.getInitParameter(paramName);
System.out.println(paramName+":"+paramValue);filter讲解：
filterChain讲解
项目：day1900filter
项目架构：
FilterDemo1.java.
package com.itheima.filter;
import java.io.IOException;
import java.util.Enumeration;
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 FilterDemo1 implements Filter {
private FilterConfig config;//用于读取初始化参数 <init-param>中的值
public FilterDemo1() {
System.out.println("FilterDemo1被实例化了");
}
public void destroy() {
System.out.println("FilterDemo1被销毁了");
}
//拦截，放行
public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
/*
* <init-param>
<param-name>encoding</param-name>
<param-value>UTF-8</param-value>
</init-param>
String value = config.getInitParameter("encoding");
System.out.println(value);
*/
Enumeration<String> enumss = config.getInitParameterNames();//取到所有参数名称 <param-name>encoding</param-name>
while(enumss.hasMoreElements()){
String paramName = enumss.nextElement();
String value = config.getInitParameter(paramName);
System.out.println(value);
}
System.out.println("FilterDemo1放行前");
response.getWriter().write("FilterDemo1放行前前");
chain.doFilter(request, response);//放行
System.out.println("FilterDemo1放行后");
}
public void init(FilterConfig fConfig) throws ServletException {
this.config = fConfig;
System.out.println("初始化了");
}
}FilterDemo2.java
package com.itheima.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;
/**
* Servlet Filter implementation class FilterDemo2
*/
public class FilterDemo2 implements Filter {
/**
* Default constructor.
*/
public FilterDemo2() {
// TODO Auto-generated constructor stub
}
/**
* @see Filter#destroy()
*/
public void destroy() {
// TODO Auto-generated method stub
}
/**
* @see Filter#doFilter(ServletRequest, ServletResponse, FilterChain)
*/
public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
System.out.println("FilterDemo2放行前");
chain.doFilter(request, response);
System.out.println("FilterDemo2放行后");
}
/**
* @see Filter#init(FilterConfig)
*/
public void init(FilterConfig fConfig) throws ServletException {
// TODO Auto-generated method stub
}
}index.jsp
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<base href="http://blog.163.com/faith_yee/blog/<%=basePath%>">
<title>My JSP 'index.jsp' starting page</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">
<!--
<link rel="stylesheet" type="text/css" href="http://blog.163.com/faith_yee/blog/styles.css">
-->
</head>
<body>
This is my JSP page. <br>
<%
System.out.println("目标资源：JSP");
%>
</body>
</html>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" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" version="2.5"> <display-name></display-name> <welcome-file-list> <welcome-file>index.jsp</welcome-file> </welcome-file-list> <filter> <filter-name>FilterDemo1</filter-name> <filter-class>com.itheima.filter.FilterDemo1</filter-class> <init-param> <param-name>encoding</param-name> <param-value>UTF-8</param-value> </init-param> <init-param> <param-name>name</param-name> <param-value>AJ</param-value> </init-param> </filter> <filter> <display-name>FilterDemo2</display-name> <filter-name>FilterDemo2</filter-name> <filter-class>com.itheima.filter.FilterDemo2</filter-class> </filter> <filter-mapping> <filter-name>FilterDemo2</filter-name> <url-pattern>/*</url-pattern> </filter-mapping> <filter-mapping> <filter-name>FilterDemo1</filter-name> <url-pattern>/*</url-pattern> </filter-mapping> </web-app>
测试：
总结：在filter里如何获得web.xml配置文件的属性值：
由于之前例子发现filter在服务器启动时就已经进行配置文件初始化了，所以自然会执行filter的构造函数和init的方法，该方法的参数是FilterConfig类型，init（）方法会读取配置文件给该filter进行初始化，所以我们可以从该方法入手获取FilterConfig类型变量，首先我们定义一个FilterConfig类型的全局变量，然后通过init（）方法进行传值到全局变量，然后全局变量就可以获得FilterConfig类型的对象，然后可以执行对象中的方法getInitParameterNames（）或getInitParameter(）去获取配置文件的属性名或属性值。
四、过滤器解决乱码问题简单版
三个示例：1、编码过滤 2、动态资源无缓存 3、静态资源缓存
实例 servlet解决乱码：
1、取名 2、输出回jsp，测试有没有乱码 用filter解决编码的问题（集中问题解决） 思考：以后执行servlet时，都通过filter过滤，那么就可以都解决编码乱码的问题了
总结：如果要集中解决问题：用过滤器
五、动态资源不缓存的过滤器
过滤器解决post的乱码待会再讲解get提交的代码
在dofilter里对强转request和response成HttpServlet的 //以上的技巧叫调包！！在过滤器里经常使用
开始设置不缓存
response.setHeader("Expirse","-1");
response.setHeader("Cache-Control","no-cache");
response.setHeader("pragma","no-cache");测试：在IE里访问addcustomer.jsp
在IE设置里查看缓存，找到目标后查看文件的过期时间！！对比本地时间去判断！
以此实现动态资源不缓存
六、静态资源缓存的过滤器
然后在过滤器里进一步筛选在该过滤器的配置器里加参数属性进行筛选 配置文件
思路：
1、因为静态资源过多，所以配置成/**/，但为了只过滤静态资源，所以考虑用参数来区分
2、读取初始化参数，
{
那么我们怎么知道客户端访问的路径是什么？
2、得到用户访问的资源（主要取它的类型，而文件类型由扩展名决定，然后把调包方式复制过来），用来获取后缀名
}
读取初始化参数，以找到这个类型的资源缓存时间
3、设置缓存时间
response.setDateHeader("Expires",System.currentTimeMillis()+Integer.parseInt(time)+60*60*1000);测试：在测试前准备一些静态资源： 访问index.html-->里面会访问静态资源： 然后去IE设置文件里查看缓存过期时间
项目：day1901filterExample：CharacterEncodingFilter
项目架构：
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" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" version="2.5"> <display-name></display-name> <servlet> <servlet-name>UserRegistServlet</servlet-name> <servlet-class>com.itheima.servlet.UserRegistServlet</servlet-class> </servlet> <servlet> <servlet-name>CustomerRegistServlet</servlet-name> <servlet-class>com.itheima.servlet.CustomerRegistServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>UserRegistServlet</servlet-name> <url-pattern>/servlet/UserRegistServlet</url-pattern> </servlet-mapping> <servlet-mapping> <servlet-name>CustomerRegistServlet</servlet-name> <url-pattern>/servlet/CustomerRegistServlet</url-pattern> </servlet-mapping> <welcome-file-list> <welcome-file>index.jsp</welcome-file> </welcome-file-list> <filter> <display-name>CharacterEncodingFilter</display-name> <filter-name>CharacterEncodingFilter</filter-name> <filter-class>com.itheima.filter.CharacterEncodingFilter</filter-class> </filter> <filter-mapping> <filter-name>CharacterEncodingFilter</filter-name> <url-pattern>/*</url-pattern> </filter-mapping> <filter> <display-name>DyncSourceNoNeedCache</display-name> <filter-name>DyncSourceNoNeedCache</filter-name> <filter-class>com.itheima.filter.DyncSourceNoNeedCache</filter-class> </filter> <filter-mapping> <filter-name>DyncSourceNoNeedCache</filter-name> <url-pattern>*.jsp</url-pattern> </filter-mapping> <filter-mapping> <filter-name>DyncSourceNoNeedCache</filter-name> <url-pattern>/servlet/*</url-pattern> </filter-mapping> <filter> <display-name>StaticSourceNeedCache</display-name> <filter-name>StaticSourceNeedCache</filter-name> <filter-class>com.itheima.filter.StaticSourceNeedCache</filter-class> <init-param> <param-name>html</param-name> <param-value>1</param-value><!-- 小时 --> </init-param> <init-param> <param-name>css</param-name> <param-value>2</param-value><!-- 小时 --> </init-param> <init-param> <param-name>js</param-name> <param-value>3</param-value><!-- 小时 --> </init-param> </filter> <filter-mapping> <filter-name>StaticSourceNeedCache</filter-name> <url-pattern>/*</url-pattern> </filter-mapping> </web-app>
CharacterEncodingFilter.java
package com.itheima.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;
/**
* Servlet Filter implementation class CharacterEncodingFilter
*/
public class CharacterEncodingFilter implements Filter {
/**
* Default constructor.
*/
public CharacterEncodingFilter() {
}
public void destroy() {
}
public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
request.setCharacterEncoding("UTF-8");//post提交有效
response.setCharacterEncoding("UTF-8");//响应结果的编码
response.setContentType("text/html;charset=UTF-8");//告诉浏览器用什么编码，它也有上一行代码的功能
chain.doFilter(request, response);
}
public void init(FilterConfig fConfig) throws ServletException {
}
}DyncSourceNoNeedCache.java
package com.itheima.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;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* Servlet Filter implementation class DyncSourceNoNeedCache
*/
public class DyncSourceNoNeedCache implements Filter {
/**
* Default constructor.
*/
public DyncSourceNoNeedCache() {
// TODO Auto-generated constructor stub
}
/**
* @see Filter#destroy()
*/
public void destroy() {
// TODO Auto-generated method stub
}
/**
* @see Filter#doFilter(ServletRequest, ServletResponse, FilterChain)
*/
public void doFilter(ServletRequest req, ServletResponse resp, FilterChain chain) throws IOException, ServletException {
HttpServletRequest request ;
HttpServletResponse response;
try {
request = (HttpServletRequest) req;
response = (HttpServletResponse) resp;
//调包
response.setHeader("Expires", "-1");
response.setHeader("Cache-Control", "no-cache");
response.setHeader("Pragma", "no-cache");
} catch (Exception e) {
e.printStackTrace();
throw new RuntimeException("non-http request or response");
}
chain.doFilter(request, response);
}
/**
* @see Filter#init(FilterConfig)
*/
public void init(FilterConfig fConfig) throws ServletException {
// TODO Auto-generated method stub
}
}StaticSourceNeedCache.java
package com.itheima.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;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class StaticSourceNeedCache implements Filter {
private FilterConfig config;
public StaticSourceNeedCache() {
}
public void destroy() {
}
public void doFilter(ServletRequest req, ServletResponse resp, FilterChain chain) throws IOException, ServletException {
//1.因为静态资源过多，所以配置成/*,但为了只过滤静态资源，所以考虑用参数来区分
HttpServletRequest request ;
HttpServletResponse response;
try {
request = (HttpServletRequest) req;
response = (HttpServletResponse) resp;
} catch (Exception e) {
e.printStackTrace();
throw new RuntimeException("non-http request or response");
}
//2.得到用户访问的资源（主要取它的类型，而文件类型由扩展名决定）
String path = request.getRequestURI();//资源名 /dsfdsfsdfds/dsfdsfs/a.html
String extensionName = path.substring(path.lastIndexOf(".")+1);//得到扩展名
//3.读取初始化参数，以找到这个类型的资源缓存时间
String time ="0";
String time1 = config.getInitParameter(extensionName);
if(time1!=null){
time = time1;
}
//4.设置缓存时间
response.setDateHeader("Expires", System.currentTimeMillis()+Integer.parseInt(time)*60*60*1000);//单位：毫秒
chain.doFilter(request, response);
}
public void init(FilterConfig fConfig) throws ServletException {
this.config = fConfig;
}
}CustomerRegistServlet.java
package com.itheima.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 CustomerRegistServlet extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
/*request.setCharacterEncoding("UTF-8");//post提交有效
response.setCharacterEncoding("UTF-8");//响应结果的编码
response.setContentType("text/html;charset=UTF-8");//告诉浏览器用什么编码，它也有上一行代码的功能
*/
String value = request.getParameter("name");
response.getWriter().write(value);
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
this.doGet(request, response);
}
}UserRegistServlet.java
package com.itheima.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 UserRegistServlet extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
/* request.setCharacterEncoding("UTF-8");//post提交有效
response.setCharacterEncoding("UTF-8");//响应结果的编码
response.setContentType("text/html;charset=UTF-8");//告诉浏览器用什么编码，它也有上一行代码的功能
*/
String value = request.getParameter("name");
response.getWriter().write(value);
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
this.doGet(request, response);
}
}addCustomer.jsp
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>客户注册</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<!--
<link rel="stylesheet" type="text/css" href="http://blog.163.com/faith_yee/blog/styles.css">
-->
</head>
<body>
<form action="${pageContext.request.contextPath}/servlet/CustomerRegistServlet" method="post">
<input name="name"/><input type="submit" value="保存"/>
</form>
</body>
</html>addUser.jsp
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>用户注册</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<!--
<link rel="stylesheet" type="text/css" href="http://blog.163.com/faith_yee/blog/styles.css">
-->
</head>
<body>
<form action="${pageContext.request.contextPath}/servlet/UserRegistServlet" method="post">
<input name="name"/><input type="submit" value="保存"/>
</form>
</body>
</html>index.html
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <title>index.html</title> <meta http-equiv="keywords" content="keyword1,keyword2,keyword3"> <meta http-equiv="description" content="this is my page"> <meta http-equiv="content-type" content="text/html; charset=UTF-8"> <link rel="stylesheet" type="text/css" href="http://blog.163.com/faith_yee/blog/css/main.css"> <script type="text/javascript" src="http://blog.163.com/faith_yee/blog/js/1.js"></script> </head> <body> hello ,good morning. </body> </html>
index.jsp
<%@ page language="java" import="java.util.*" pageEncoding="ISO-8859-1"%> <% String path = request.getContextPath(); String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/"; %> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <base href="http://blog.163.com/faith_yee/blog/<%=basePath%>"> <title>My JSP 'index.jsp' starting page</title> <meta http-equiv="pragma" content="no-cache"> <meta http-equiv="cache-control" content="no-cache"> <meta http-equiv="expires" content="0"> <meta http-equiv="keywords" content="keyword1,keyword2,keyword3"> <meta http-equiv="description" content="This is my page"> <!-- <link rel="stylesheet" type="text/css" href="http://blog.163.com/faith_yee/blog/styles.css"> --> </head> <body> This is my JSP page. <br> </body> </html>
测试addCustomer
测试addUser
测试 DyncSourceNoNeedCache
测试 StaticSourceNeedCache
七、自动登录
示例4、自动登录分析资料：
项目：day1902autoLogin
项目架构：
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" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" version="2.5"> <display-name></display-name> <servlet> <servlet-name>LoginServlet</servlet-name> <servlet-class>com.itheima.servlet.LoginServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>LoginServlet</servlet-name> <url-pattern>/servlet/LoginServlet</url-pattern> </servlet-mapping> <welcome-file-list> <welcome-file>index.jsp</welcome-file> </welcome-file-list> <filter> <display-name>CharacterEncodingFilter</display-name> <filter-name>CharacterEncodingFilter</filter-name> <filter-class>com.itheima.filter.CharacterEncodingFilter</filter-class> </filter> <filter-mapping> <filter-name>CharacterEncodingFilter</filter-name> <url-pattern>/*</url-pattern> </filter-mapping> <filter> <display-name>AutoLoginFilter</display-name> <filter-name>AutoLoginFilter</filter-name> <filter-class>com.itheima.filter.AutoLoginFilter</filter-class> </filter> <filter-mapping> <filter-name>AutoLoginFilter</filter-name> <url-pattern>/*</url-pattern> </filter-mapping> </web-app>
User.java
package com.itheima.domain;
import java.io.Serializable;
public class User implements Serializable {
private String username;
private String password;
public User(String username, String password) {
super();
this.username = username;
this.password = password;
}
public User() {
super();
}
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
}UserDB.java
package com.itheima.domain;
import java.util.ArrayList;
import java.util.List;
public class UserDB {
private static List<User> users = new ArrayList<User>();
static{
users.add(new User("郭女士","123"));
users.add(new User("丁先生","123"));
users.add(new User("fj","123"));
}
public static User findUser(String username,String password){
for(User u:users){
if(username.equals(u.getUsername())&&password.equals(u.getPassword())){
return u;
}
}
return null;
}
public static User findUser(String username){
for(User u:users){
if(username.equals(u.getUsername())){
return u;
}
}
return null;
}
}AutoLoginFilter.java
package com.itheima.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;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import com.itheima.domain.User;
import com.itheima.domain.UserDB;
import com.itheima.util.Base64Util;
import com.itheima.util.Md5Util;
/**
* Servlet Filter implementation class AutoLoginFilter
*/
public class AutoLoginFilter implements Filter {
/**
* Default constructor.
*/
public AutoLoginFilter() {
// TODO Auto-generated constructor stub
}
public void destroy() {
}
public void doFilter(ServletRequest req, ServletResponse resp, FilterChain chain) throws IOException, ServletException {
HttpServletRequest request = (HttpServletRequest) req;
HttpServletResponse response = (HttpServletResponse) resp;
//读取session中的值
User u = (User)request.getSession().getAttribute("user");
if(u==null){
//2.没有登录，可以读Cookie
Cookie cs [] = request.getCookies();
//3.遍历
if(cs==null){
return ;
}
Cookie userCookie = null;
if(cs!=null && cs.length>0){
for (int i = 0; i < cs.length; i++) {
Cookie c = cs[i];
if("userinfo".equals(c.getName())){
//如果找到了你想的cookie
userCookie = c;
break;
}
}
}
//4.说明存在要找的Cookie
if(userCookie!=null){
String username_pwd = userCookie.getValue();
String b64username = username_pwd.split("_")[0];//取b64编码后的用户名
String md5pwd = username_pwd.split("_")[1];//取md5加密后的密码
//5.还原用户名
String trueUsername = Base64Util.decode(b64username);
//6.根据用户名，到UserDB中查找，得到一个User对象
User uu = UserDB.findUser(trueUsername);
if(uu!=null){
if(md5pwd.equals(Md5Util.encode(uu.getPassword()))){
request.getSession().setAttribute("user", uu);
}
}
}
}
chain.doFilter(request, response);
}
public void init(FilterConfig fConfig) throws ServletException {
}
}CharacterEncodingFilter.java
package com.itheima.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;
/**
* Servlet Filter implementation class CharacterEncodingFilter
*/
public class CharacterEncodingFilter implements Filter {
/**
* Default constructor.
*/
public CharacterEncodingFilter() {
}
public void destroy() {
}
public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
request.setCharacterEncoding("UTF-8");//post提交有效
response.setCharacterEncoding("UTF-8");//响应结果的编码
response.setContentType("text/html;charset=UTF-8");//告诉浏览器用什么编码，它也有上一行代码的功能
chain.doFilter(request, response);
}
public void init(FilterConfig fConfig) throws ServletException {
}
}LoginServlet.java
package com.itheima.servlet;
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;
import com.itheima.domain.User;
import com.itheima.domain.UserDB;
import com.itheima.util.Base64Util;
import com.itheima.util.Md5Util;
public class LoginServlet extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
//1.获取参数
String username = request.getParameter("username");
String password = request.getParameter("password");
String expires = request.getParameter("expires");
//2.验证用户的合法性
User u = UserDB.findUser(username, password);
//3.判断是非法用户，直接返回到登录页
if(u==null){
response.getWriter().write("登录失败，2秒后请重新登录");
response.setHeader("Refresh", "2;URL="+request.getContextPath()+"/login.jsp");
return;
}
//4.合法用户，将用户信息存入session
request.getSession().setAttribute("user", u);
//5.产生一个Cookie，用于保存登录用户的用户名_密码 （base64username_md5password)
Cookie c = new Cookie("userinfo",Base64Util.encode(u.getUsername())+"_"+Md5Util.encode(u.getPassword()));
//6.设置cookie的path路径
c.setPath(request.getContextPath());//代表当前应用请求时，cookie信息都发送给服务器
//7.设置cookie的存活时间
if("never".equals(expires)){
c.setMaxAge(0);
}else if("month".equals(expires)){
c.setMaxAge(30*24*60*60);//秒
}else if("year".equals(expires)){
c.setMaxAge(365*24*60*60);
}else if("forever".equals(expires)){
c.setMaxAge(Integer.MAX_VALUE);
}
//8.发送给浏览器
response.addCookie(c);
//9重定向到index.jsp
response.sendRedirect(request.getContextPath()+"/index.jsp");
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
this.doGet(request, response);
}
}Base64Util.java
package com.itheima.util;
import java.io.IOException;
import sun.misc.BASE64Decoder;
import sun.misc.BASE64Encoder;
public class Base64Util {
//编码
public static String encode(String oldStr){
BASE64Encoder b64Encoder = new BASE64Encoder();
return b64Encoder.encode(oldStr.getBytes());
}
//解码
public static String decode(String oldStr){
try {
BASE64Decoder b64Decoder = new BASE64Decoder();
byte []newStr = b64Decoder.decodeBuffer(oldStr);
return new String(newStr);
} catch (IOException e) {
e.printStackTrace();
throw new RuntimeException(e);
}
}
}Md5Util.java
package com.itheima.util;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import sun.misc.BASE64Encoder;
public class Md5Util {
public static String encode(String oldStr){
try {
MessageDigest md5 = MessageDigest.getInstance("md5");
byte [] newStr = md5.digest(oldStr.getBytes());
BASE64Encoder b64 = new BASE64Encoder();
return b64.encode(newStr);
} catch (NoSuchAlgorithmException e) {
e.printStackTrace();
throw new RuntimeException(e);
}
}
public static void main(String[] args) {
for(int i=1;i<20;i++){
String newString = Md5Util.encode("abc"+i);
System.out.println(newString);
}
}
}bbs.jsp
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title></title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
</head>
<body>
${sessionScope.user.username}
</body>
</html>index.jsp
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>XX网站</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">
<!--
<link rel="stylesheet" type="text/css" href="http://blog.163.com/faith_yee/blog/styles.css">
-->
</head>
<body>
<c:if test="${sessionScope.user==null}">
<a href="http://blog.163.com/faith_yee/blog/${pageContext.request.contextPath}/login.jsp">登录</a>
</c:if>
<c:if test="${sessionScope.user!=null}">
欢迎您：${user.username}<a href="http://blog.163.com/faith_yee/blog/#">注销</a>
</c:if>
<hr/>
XX网站
<a href="http://blog.163.com/faith_yee/blog/${pageContext.request.contextPath}/bbs.jsp">帖子</a>
</body>
</html>login.jsp
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title></title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
</head>
<body>
<form action="${pageContext.request.contextPath}/servlet/LoginServlet" method="post">
用户名：<input type="text" name="username"/><br/>
密码：<input type="password" name="password"/><br/>
登录有效期：<input type="radio" name="expires" value="never" checked="checked">无
<input type="radio" name="expires" value="month">一个月
<input type="radio" name="expires" value="year">一年
<input type="radio" name="expires" value="forever">永久<br/>
<input type="submit" value="登录"/>
</form>
</body>
</html>测试：
util-->Base64Util
//编码
public static String encode(oldStr){
BASE64Encoder b64Encode = new BASE64Encoder();
return b64Encoder.encode(oldStr.getBytes());
}
//解码
public static String decode(String oldStr){
BASE64Decoder b64Decoder = new BASE64Decoder();
byte []newStr = b64Decoder.decodeBuffer(oldStr);//stream类型
return new String(newStr);
}
该工具类把用户名编码进行编码传输！util--->Md5Util
Md5不可逆
public static String encode (String oldStr){
MessageDigest md5 = MessageDigest.getInstance("md5");
byte[] newStr = md5.digest(oldStr.getBytes());
//return new String (newStr);
//以上这种加密不好使，会产生一些无厘头的中文，所以为了传输这md5产生的加密文件，所以结合上面的Base64util来给加密文件都进行编码！！传输到另一方进行解码！！
}测试工具类
以上主要是为了通过客户端发来用户名和密码，发送给客户端，通过md5把密码加密后传输到服务器端，服务器端经过匹配md5加密后的密码去取出数据库中的用户资料，这个传输过程使用base64编码解码进行传输。。
Base64Util是3字节变成4字节
八、实例
1、全站编码过滤器问题是，我们输入的那么多jsp，怎么弄一个功能更强大的filter去解决get/post的乱码问题 在web.xml里加上<init-param>属性配置 改进CHaracterEncodingFilter 把代码写活，适用型强 调包-->新类MyHttpServletRequset(内部类)：！！！调包后换了一个功能更强大的 包装设计模式
2、包装设计模式解释
包装设计模式
MyBufferReader extends BufferdReader{
private BufferedReader reader ;
public MyBufferedReader(Reader in){
super(in);
this.reader =(BufferedReader)in;
}
public String readLine() throws IOException{
String content = reader.readLine();
if(content!=null)
return (i++)+content;
return super.readLine();
}
}
//包装模式包装的是对象（本身就是一个包装类，此时可以简化写法）
在super()完以前的继承类后，就改写要加强的方法就OK3、脏话过滤器
首先要有一个脏话数据库 在filter--->DirtyWordsFilter--->过滤路径：全部
在doFilter
{
String woeds[]={"叫兽","禽兽","FUCK"};
调包
形成过滤器链
目的：改写方法
}4、html过滤器
写Html过滤器filter-->HtmlFilter 在tomcat里的example里找一个Html的filter去复制里面的代码 替换-->令标签代码无效 以下的所有示例都是换包再发送出去，这就是包装设计模式
项目：day1903advanceExample-->CharacterEncodingFilter
项目架构：
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" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" version="2.5"> <display-name></display-name> <servlet> <servlet-name>UserRegistServlet</servlet-name> <servlet-class>com.itheima.servlet.UserRegistServlet</servlet-class> </servlet> <servlet> <servlet-name>GzipDemo1</servlet-name> <servlet-class>com.itheima.servlet.GzipDemo1</servlet-class> </servlet> <servlet> <servlet-name>GzipDemo2</servlet-name> <servlet-class>com.itheima.servlet.GzipDemo2</servlet-class> </servlet> <servlet-mapping> <servlet-name>UserRegistServlet</servlet-name> <url-pattern>/servlet/UserRegistServlet</url-pattern> </servlet-mapping> <servlet-mapping> <servlet-name>GzipDemo1</servlet-name> <url-pattern>/servlet/GzipDemo1</url-pattern> </servlet-mapping> <servlet-mapping> <servlet-name>GzipDemo2</servlet-name> <url-pattern>/servlet/GzipDemo2</url-pattern> </servlet-mapping> <welcome-file-list> <welcome-file>index.jsp</welcome-file> </welcome-file-list> <filter> <display-name>CharacterEncodingFilter</display-name> <filter-name>CharacterEncodingFilter</filter-name> <filter-class>com.itheima.filter.CharacterEncodingFilter</filter-class> <init-param> <param-name>encode</param-name> <param-value>UTF-8</param-value> </init-param> </filter> <filter-mapping> <filter-name>CharacterEncodingFilter</filter-name> <url-pattern>/*</url-pattern> </filter-mapping> <filter> <display-name>DirtyWordsFilter</display-name> <filter-name>DirtyWordsFilter</filter-name> <filter-class>com.itheima.filter.DirtyWordsFilter</filter-class> </filter> <filter-mapping> <filter-name>DirtyWordsFilter</filter-name> <url-pattern>/*</url-pattern> </filter-mapping> <filter> <display-name>HtmlFilter</display-name> <filter-name>HtmlFilter</filter-name> <filter-class>com.itheima.filter.HtmlFilter</filter-class> </filter> <filter-mapping> <filter-name>HtmlFilter</filter-name> <url-pattern>/*</url-pattern> </filter-mapping> <filter> <display-name>GzipFilter</display-name> <filter-name>GzipFilter</filter-name> <filter-class>com.itheima.filter.GzipFilter</filter-class> </filter> <filter-mapping> <filter-name>GzipFilter</filter-name> <url-pattern>/*</url-pattern> </filter-mapping> </web-app>
CharacterEncodingFilter.java
package com.itheima.filter;
import java.io.IOException;
import java.io.UnsupportedEncodingException;
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 javax.servlet.http.HttpServletResponse;
public class CharacterEncodingFilter implements Filter {
private FilterConfig config;
public CharacterEncodingFilter() {
}
public void destroy() {
}
public void doFilter(ServletRequest req, ServletResponse resp, FilterChain chain) throws IOException, ServletException {
String encode = "UTF-8";
String paramValue = config.getInitParameter("encode");
if(paramValue!=null){
encode =paramValue;
}
HttpServletRequest request = (HttpServletRequest) req;
HttpServletResponse response = (HttpServletResponse) resp;
request.setCharacterEncoding(encode);//post提交有效
response.setCharacterEncoding(encode);//响应结果的编码
response.setContentType("text/html;charset="+encode);//告诉浏览器用什么编码，它也有上一行代码的功能
//调包
MyHttpServletRequest myrequest = new MyHttpServletRequest(request);
chain.doFilter(myrequest, response);
}
public void init(FilterConfig fConfig) throws ServletException {
this.config = fConfig;
}
//包装设计模式
public class MyHttpServletRequest extends HttpServletRequestWrapper {
public MyHttpServletRequest(HttpServletRequest request) {
super(request);
}
@Override
public String getParameter(String name) {
String value = super.getParameter(name);
String method = super.getMethod();//得到请求的类型 get/post
if("get".equalsIgnoreCase(method)){
try {
value = new String(value.getBytes("iso-8859-1"),super.getCharacterEncoding());
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
}
}
return value;
}
}
}DirtyWordsFilter.java
package com.itheima.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;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;
import javax.servlet.http.HttpServletResponse;
public class DirtyWordsFilter implements Filter {
public DirtyWordsFilter() {
}
public void destroy() {
}
public void doFilter(ServletRequest req, ServletResponse resp, FilterChain chain) throws IOException, ServletException {
HttpServletRequest request = (HttpServletRequest) req;
HttpServletResponse response = (HttpServletResponse) resp;
//调包,这样下一层在用时，就会使用重写之后的getParameter()方法
MyHttpServletRequestDirtyWords mydirtywordsrequest= new MyHttpServletRequestDirtyWords(request);
chain.doFilter(mydirtywordsrequest, response);
}
public void init(FilterConfig fConfig) throws ServletException {
}
public class MyHttpServletRequestDirtyWords extends HttpServletRequestWrapper{
public MyHttpServletRequestDirtyWords(HttpServletRequest request) {
super(request);
}
@Override
public String getParameter(String name) {
String words []= {"叫兽","禽兽","FUCK"};
String oldParam = super.getParameter(name);
if(oldParam!=null)
for(String word:words){
oldParam =oldParam.replace(word, "***");//只替换脏话
}
return oldParam;
}
}
}HtmlFilter.java
package com.itheima.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;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;
import javax.servlet.http.HttpServletResponse;
/**
* Servlet Filter implementation class HtmlFilter
*/
public class HtmlFilter implements Filter {
/**
* Default constructor.
*/
public HtmlFilter() {
// TODO Auto-generated constructor stub
}
/**
* @see Filter#destroy()
*/
public void destroy() {
// TODO Auto-generated method stub
}
/**
* @see Filter#doFilter(ServletRequest, ServletResponse, FilterChain)
*/
public void doFilter(ServletRequest req, ServletResponse resp, FilterChain chain) throws IOException, ServletException {
HttpServletRequest request = (HttpServletRequest) req;
HttpServletResponse response = (HttpServletResponse) resp;
//< < > >
MyHttpServletHtmlRequest htmlRequest = new MyHttpServletHtmlRequest(request);
chain.doFilter(htmlRequest, response);
}
/**
* @see Filter#init(FilterConfig)
*/
public void init(FilterConfig fConfig) throws ServletException {
// TODO Auto-generated method stub
}
public class MyHttpServletHtmlRequest extends HttpServletRequestWrapper {
public MyHttpServletHtmlRequest(HttpServletRequest request) {
super(request);
}
@Override
public String getParameter(String name) {
String value = super.getParameter(name);
return filter(value);
}
public String filter(String message) {
if (message == null)
return (null);
char content[] = new char[message.length()];
message.getChars(0, message.length(), content, 0);
StringBuffer result = new StringBuffer(content.length + 50);
for (int i = 0; i < content.length; i++) {
switch (content[i]) {
case '<':
result.append("<");
break;
case '>':
result.append(">");
break;
case '&':
result.append("&");
break;
case '"':
result.append(""");
break;
default:
result.append(content[i]);
}
}
return (result.toString());
}
}
}UserRegistServlet.java
package com.itheima.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 UserRegistServlet extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
String name = request.getParameter("name");
//name = new String(name.getBytes("iso-8859-1"),"UTF-8");
System.out.println(name);
response.getWriter().write(name);
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
this.doGet(request, response);
}
}addCustomer.jsp
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>客户注册</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<!--
<link rel="stylesheet" type="text/css" href="http://blog.163.com/faith_yee/blog/styles.css">
-->
</head>
<body>
<form action="${pageContext.request.contextPath}/servlet/CustomerRegistServlet" method="post">
<input name="name"/><input type="submit" value="保存"/>
</form>
</body>
</html>addUser.jsp
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>用户注册</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<!--
<link rel="stylesheet" type="text/css" href="http://blog.163.com/faith_yee/blog/styles.css">
-->
</head>
<body>
<form action="${pageContext.request.contextPath}/servlet/UserRegistServlet" method="post">
<input name="name"/><input type="submit" value="保存"/>
</form>
</body>
</html>
总结：
CharacterEncodingFilter.java
DirtyWordsFilter.java
HtmlFilter.java
都是使用了包装设计模式：在filter里使用了自定义的内部类，利用子父类的关系把request发给继承了子类的自定义类去进行包装增强功能，并返回一个实现了自己新的功能方法的返回给新的自定义类，最后放行的时候就返回新的包装后的对象。提供给servlet去使用。
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