【web】赵雅智_Filter常见应用
来源：互联网 发布：mysql 长整型 编辑：程序博客网 时间：2024/05/17 14:16
统一全站字符编码的过滤器
- 通过配置参数encoding指明使用何种字符编码,以处理Html Form请求参数的中文问题
没配置过滤器：
CharseterEncodingFilter.java
package com.hbsi.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;public class CharseterEncodingFilter implements Filter {private FilterConfig config = null;private String defaultCharset = "UTF-8";public void destroy() {// TODO Auto-generated method stub}public void doFilter(ServletRequest request, ServletResponse response,FilterChain chain) throws IOException, ServletException {// TODO Auto-generated method stubString charset = config.getInitParameter("charset");if(charset==null){charset = defaultCharset;}request.setCharacterEncoding(charset);//如果是servlet进行相应设置response.setCharacterEncoding("UTF-8");response.setContentType("text/html;charset="+charset);chain.doFilter(request, response);}public void init(FilterConfig filterConfig) throws ServletException {// TODO Auto-generated method stubthis.config = filterConfig;}}web.xml
<?xml version="1.0" encoding="UTF-8"?><web-app version="2.5" 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_2_5.xsd"><!-- <filter><filter-name>FilterChain</filter-name><filter-class>com.hbsi.filter.FilterChain</filter-class></filter><filter-mapping><filter-name>FilterChain</filter-name><url-pattern>*.jsp</url-pattern></filter-mapping><filter><filter-name>FilterDemo1</filter-name><filter-class>com.hbsi.filter.FilterDemo1</filter-class></filter><filter-mapping><filter-name>FilterDemo1</filter-name><url-pattern>*.html</url-pattern></filter-mapping><filter><filter-name>FilterShengZhou</filter-name><filter-class>com.hbsi.filter.FilterShengZhou</filter-class><init-param><param-name>abc</param-name><param-value>aaaaa</param-value></init-param></filter><filter-mapping><filter-name>FilterShengZhou</filter-name><url-pattern>*.jsp</url-pattern></filter-mapping>--> <servlet> <description>This is the description of my J2EE component</description> <display-name>This is the display name of my J2EE component</display-name> <servlet-name>LuanMaServlet</servlet-name> <servlet-class>com.hbsi.servlet.LuanMaServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>LuanMaServlet</servlet-name> <url-pattern>/servlet/luanMa.do</url-pattern> </servlet-mapping> <welcome-file-list> <welcome-file>index.jsp</welcome-file> </welcome-file-list></web-app>
LuanMaServlet.java
package com.hbsi.servlet;import java.io.IOException;import java.io.PrintWriter;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;public class LuanMaServlet extends HttpServlet {public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {String city = request.getParameter("city");response.getWriter().write(city);}public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {doGet(request, response);}}luanMa.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="<%=basePath%>"> <title>My JSP 'luanMa.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="styles.css">--> </head> <body> <form action="servlet/luanMa.do" method="post"> 城市:<input type="text" name="city"/> <input type="submit" value="提交"/> </form> </body></html>
配置过滤器：
web.xml
<?xml version="1.0" encoding="UTF-8"?><web-app version="2.5" 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_2_5.xsd"><!-- <filter><filter-name>FilterChain</filter-name><filter-class>com.hbsi.filter.FilterChain</filter-class></filter><filter-mapping><filter-name>FilterChain</filter-name><url-pattern>*.jsp</url-pattern></filter-mapping><filter><filter-name>FilterDemo1</filter-name><filter-class>com.hbsi.filter.FilterDemo1</filter-class></filter><filter-mapping><filter-name>FilterDemo1</filter-name><url-pattern>*.html</url-pattern></filter-mapping><filter><filter-name>FilterShengZhou</filter-name><filter-class>com.hbsi.filter.FilterShengZhou</filter-class><init-param><param-name>abc</param-name><param-value>aaaaa</param-value></init-param></filter><filter-mapping><filter-name>FilterShengZhou</filter-name><url-pattern>*.jsp</url-pattern></filter-mapping>--><filter><filter-name>CharseterEncodingFilter</filter-name> <filter-class>com.hbsi.filter.CharseterEncodingFilter</filter-class> <init-param> <param-name>charset</param-name> <param-value>UTF-8</param-value></init-param></filter><filter-mapping><filter-name>CharseterEncodingFilter</filter-name><url-pattern>*.jsp</url-pattern></filter-mapping><filter-mapping><filter-name>CharseterEncodingFilter</filter-name><url-pattern>/servlet/*</url-pattern></filter-mapping> <servlet> <description>This is the description of my J2EE component</description> <display-name>This is the display name of my J2EE component</display-name> <servlet-name>LuanMaServlet</servlet-name> <servlet-class>com.hbsi.servlet.LuanMaServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>LuanMaServlet</servlet-name> <url-pattern>/servlet/luanMa.do</url-pattern> </servlet-mapping> <welcome-file-list> <welcome-file>index.jsp</welcome-file> </welcome-file-list></web-app>
禁止浏览器缓存所有动态页面的过滤器
- 有 3 个 HTTP 响应头字段都可以禁止浏览器缓存当前页面，它们在 Servlet 中的示例代码如下：
- response.setDateHeader("Expires",-1);
- response.setHeader("Cache-Control","no-cache");
- response.setHeader("Pragma","no-cache");
- 并不是所有的浏览器都能完全支持上面的三个响应头，因此最好是同时使用上面的三个响应头。
- Expires数据头：值为GMT时间值，为-1指浏览器不要缓存页面
- Cache-Control响应头有两个常用值：
- no-cache指浏览器不要缓存当前页面。
- max-age:xxx指浏览器缓存页面xxx秒。
允许缓存:不编写过滤器
NoCacheFilter.java
package com.hbsi.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 NoCacheFilter implements Filter {public void destroy() {// TODO Auto-generated method stub}public void doFilter(ServletRequest request, ServletResponse response,FilterChain chain) throws IOException, ServletException {// TODO Auto-generated method stubHttpServletRequest req = (HttpServletRequest) request;HttpServletResponse resp = (HttpServletResponse) response;resp.setDateHeader("expires",-1);resp.setHeader("Cache-Control", "no-cache");resp.setHeader("Pragma", "no-cache");chain.doFilter(req,resp);}public void init(FilterConfig filterConfig) throws ServletException {// TODO Auto-generated method stub}}web.xml
<?xml version="1.0" encoding="UTF-8"?><web-app version="2.5" 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_2_5.xsd"><!-- <filter><filter-name>FilterChain</filter-name><filter-class>com.hbsi.filter.FilterChain</filter-class></filter><filter-mapping><filter-name>FilterChain</filter-name><url-pattern>*.jsp</url-pattern></filter-mapping><filter><filter-name>FilterDemo1</filter-name><filter-class>com.hbsi.filter.FilterDemo1</filter-class></filter><filter-mapping><filter-name>FilterDemo1</filter-name><url-pattern>*.html</url-pattern></filter-mapping><filter><filter-name>FilterShengZhou</filter-name><filter-class>com.hbsi.filter.FilterShengZhou</filter-class><init-param><param-name>abc</param-name><param-value>aaaaa</param-value></init-param></filter><filter-mapping><filter-name>FilterShengZhou</filter-name><url-pattern>*.jsp</url-pattern></filter-mapping>--><filter><filter-name>CharseterEncodingFilter</filter-name> <filter-class>com.hbsi.filter.CharseterEncodingFilter</filter-class> <init-param> <param-name>charset</param-name> <param-value>UTF-8</param-value></init-param></filter><filter-mapping><filter-name>CharseterEncodingFilter</filter-name><url-pattern>*.jsp</url-pattern></filter-mapping><filter-mapping><filter-name>CharseterEncodingFilter</filter-name><url-pattern>/servlet/*</url-pattern></filter-mapping> <servlet> <description>This is the description of my J2EE component</description> <display-name>This is the display name of my J2EE component</display-name> <servlet-name>LuanMaServlet</servlet-name> <servlet-class>com.hbsi.servlet.LuanMaServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>LuanMaServlet</servlet-name> <url-pattern>/servlet/luanMa.do</url-pattern> </servlet-mapping> <welcome-file-list> <welcome-file>index.jsp</welcome-file> </welcome-file-list></web-app>
访问luanMa.jsp
编写过滤器禁止缓存：
NoCacheFilter.java
package com.hbsi.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 NoCacheFilter implements Filter {public void destroy() {// TODO Auto-generated method stub}public void doFilter(ServletRequest request, ServletResponse response,FilterChain chain) throws IOException, ServletException {// TODO Auto-generated method stubHttpServletRequest req = (HttpServletRequest) request;HttpServletResponse resp = (HttpServletResponse) response;resp.setDateHeader("expires",-1);resp.setHeader("Cache-Control", "no-cache");resp.setHeader("Pragma", "no-cache");chain.doFilter(req,resp);}public void init(FilterConfig filterConfig) throws ServletException {// TODO Auto-generated method stub}}web.xml
<?xml version="1.0" encoding="UTF-8"?><web-app version="2.5" 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_2_5.xsd"><!-- <filter><filter-name>FilterChain</filter-name><filter-class>com.hbsi.filter.FilterChain</filter-class></filter><filter-mapping><filter-name>FilterChain</filter-name><url-pattern>*.jsp</url-pattern></filter-mapping><filter><filter-name>FilterDemo1</filter-name><filter-class>com.hbsi.filter.FilterDemo1</filter-class></filter><filter-mapping><filter-name>FilterDemo1</filter-name><url-pattern>*.html</url-pattern></filter-mapping><filter><filter-name>FilterShengZhou</filter-name><filter-class>com.hbsi.filter.FilterShengZhou</filter-class><init-param><param-name>abc</param-name><param-value>aaaaa</param-value></init-param></filter><filter-mapping><filter-name>FilterShengZhou</filter-name><url-pattern>*.jsp</url-pattern></filter-mapping>--><filter><filter-name>CharseterEncodingFilter</filter-name> <filter-class>com.hbsi.filter.CharseterEncodingFilter</filter-class> <init-param> <param-name>charset</param-name> <param-value>UTF-8</param-value></init-param></filter><filter-mapping><filter-name>CharseterEncodingFilter</filter-name><url-pattern>*.jsp</url-pattern></filter-mapping><filter-mapping><filter-name>CharseterEncodingFilter</filter-name><url-pattern>/servlet/*</url-pattern></filter-mapping><filter> <filter-name>NoCahceFilter</filter-name> <filter-class>com.hbsi.filter.NoCacheFilter</filter-class> </filter><filter-mapping><filter-name>NoCahceFilter</filter-name><url-pattern>*.jsp</url-pattern></filter-mapping><filter-mapping><filter-name>NoCahceFilter</filter-name><url-pattern>/servlet/*</url-pattern></filter-mapping> <servlet> <description>This is the description of my J2EE component</description> <display-name>This is the display name of my J2EE component</display-name> <servlet-name>LuanMaServlet</servlet-name> <servlet-class>com.hbsi.servlet.LuanMaServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>LuanMaServlet</servlet-name> <url-pattern>/servlet/luanMa.do</url-pattern> </servlet-mapping> <welcome-file-list> <welcome-file>index.jsp</welcome-file> </welcome-file-list></web-app>
控制浏览器缓存页面中的静态资源的过滤器：
- 场景：有些动态页面中引用了一些图片或css文件以修饰页面效果，这些图片和css文件经常是不变化的，所以为减轻服务器的压力，可以使用filter控制浏览器缓存这些文件，以提升服务器的性能。
ExpiresFilter.java
package com.hbsi.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;//控制浏览器可以缓存js，css，jpg。public class ExpiresFilter implements Filter {private FilterConfig config;public void destroy() {// TODO Auto-generated method stub}public void doFilter(ServletRequest request, ServletResponse response,FilterChain chain) throws IOException, ServletException {// TODO Auto-generated method stubHttpServletRequest req = (HttpServletRequest) request;HttpServletResponse resp = (HttpServletResponse) response;String uri = req.getRequestURI();if(uri.endsWith(".css")){long time = Integer.parseInt(config.getInitParameter("css"))*1000;resp.setDateHeader("expires",System.currentTimeMillis()+time);}else if(uri.endsWith(".js")){long time = Integer.parseInt(config.getInitParameter("js"))*1000;resp.setDateHeader("expires",System.currentTimeMillis()+time);}else if(uri.endsWith(".jpg")){long time = Integer.parseInt(config.getInitParameter("jpg"))*1000;resp.setDateHeader("expires",System.currentTimeMillis()+time);}chain.doFilter(req, resp);}public void init(FilterConfig filterConfig) throws ServletException {// TODO Auto-generated method stubthis.config = filterConfig;}}web.xml
<?xml version="1.0" encoding="UTF-8"?><web-app version="2.5" 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_2_5.xsd"><!-- <filter><filter-name>FilterChain</filter-name><filter-class>com.hbsi.filter.FilterChain</filter-class></filter><filter-mapping><filter-name>FilterChain</filter-name><url-pattern>*.jsp</url-pattern></filter-mapping><filter><filter-name>FilterDemo1</filter-name><filter-class>com.hbsi.filter.FilterDemo1</filter-class></filter><filter-mapping><filter-name>FilterDemo1</filter-name><url-pattern>*.html</url-pattern></filter-mapping><filter><filter-name>FilterShengZhou</filter-name><filter-class>com.hbsi.filter.FilterShengZhou</filter-class><init-param><param-name>abc</param-name><param-value>aaaaa</param-value></init-param></filter><filter-mapping><filter-name>FilterShengZhou</filter-name><url-pattern>*.jsp</url-pattern></filter-mapping>--><filter><filter-name>CharseterEncodingFilter</filter-name> <filter-class>com.hbsi.filter.CharseterEncodingFilter</filter-class> <init-param> <param-name>charset</param-name> <param-value>UTF-8</param-value></init-param></filter><filter-mapping><filter-name>CharseterEncodingFilter</filter-name><url-pattern>*.jsp</url-pattern></filter-mapping><filter-mapping><filter-name>CharseterEncodingFilter</filter-name><url-pattern>/servlet/*</url-pattern></filter-mapping><filter> <filter-name>NoCahceFilter</filter-name> <filter-class>com.hbsi.filter.NoCacheFilter</filter-class> </filter><filter-mapping><filter-name>NoCahceFilter</filter-name><url-pattern>*.jsp</url-pattern></filter-mapping><filter-mapping><filter-name>NoCahceFilter</filter-name><url-pattern>/servlet/*</url-pattern></filter-mapping><filter><filter-name>ExpiresFilter</filter-name><filter-class>com.hbsi.filter.ExpiresFilter</filter-class> <init-param><param-name>css</param-name><param-value>120</param-value> </init-param><init-param><param-name>jpg</param-name><param-value>120</param-value></init-param><init-param><param-name>js</param-name><param-value>120</param-value> </init-param> </filter><filter-mapping><filter-name>ExpiresFilter</filter-name><url-pattern>*.css</url-pattern></filter-mapping><filter-mapping><filter-name>ExpiresFilter</filter-name><url-pattern>*.jpg</url-pattern></filter-mapping><filter-mapping><filter-name>ExpiresFilter</filter-name><url-pattern>*.js</url-pattern></filter-mapping> <servlet> <description>This is the description of my J2EE component</description> <display-name>This is the display name of my J2EE component</display-name> <servlet-name>LuanMaServlet</servlet-name> <servlet-class>com.hbsi.servlet.LuanMaServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>LuanMaServlet</servlet-name> <url-pattern>/servlet/luanMa.do</url-pattern> </servlet-mapping> <welcome-file-list> <welcome-file>index.jsp</welcome-file> </welcome-file-list></web-app>
expiresFilter.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="<%=basePath%>"> <title>My JSP 'expiresFilter.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="styles.css">--> </head> <body> <img src="tu.jpg"> </body></html>
实现用户自动登陆的过滤器
- 在用户登陆成功后，发送一个名称为user的cookie给客户端，cookie的值为用户名和md5加密后的密码。
- 编写一个AutoLoginFilter，这个filter检查用户是否带有名称为user的cookie来，如果有，则调用dao查询cookie的用户名和密码是否和数据库匹配，匹配则向session中存入user对象（即用户登陆标记），以实现程序完成自动登陆。
login.jsp
建表：
DBUtils连接数据库倒包
c3p0_config.xml
<?xml version="1.0" encoding="UTF-8"?><c3p0-config><default-config><property name="driverClass">com.mysql.jdbc.Driver</property><property name="jdbcUrl">jdbc:mysql://localhost:3306/filter</property><property name="user">root</property><property name="password">123456</property><property name="acquireIncrement">5</property><property name="initialPoolSize">10</property><property name="minPoolSize">5</property><property name="maxPoolSize">20</property></default-config><named-config name="mysql"><property name="driverClass">com.mysql.jdbc.Driver</property><property name="jdbcUrl">jdbc:mysql://localhost:3306/filter</property><property name="user">root</property><property name="password">123456</property><property name="acquireIncrement">5</property><property name="initialPoolSize">10</property><property name="minPoolSize">5</property><property name="maxPoolSize">20</property></named-config></c3p0-config>DBManger.java
package com.hbsi.util;import java.sql.Connection;import java.sql.PreparedStatement;import java.sql.ResultSet;import java.sql.SQLException;import javax.sql.DataSource;import com.mchange.v2.c3p0.ComboPooledDataSource;public class DBManager {private static ComboPooledDataSource ds = null;static{try{//创建连接池ds = new ComboPooledDataSource("mysql");}catch(Exception e){e.printStackTrace();}}//获取链接public static DataSource getDataSource(){return ds;}}User.java
package com.hbsi.domain;public class User {private String username;private String password;public String getPassword() {return password;}public void setPassword(String password) {this.password = password;}public void setUsername(String username) {this.username = username;}public String getUsername() {return username;}}UserDao.java
package com.hbsi.dao;import java.util.List;import com.hbsi.domain.User;public interface UserDao {public List<User> getAll();public User find(String username,String password);public User find(String username);}UserDaoImpl.java
package com.hbsi.dao;import java.util.List;import org.apache.commons.dbutils.QueryRunner;import org.apache.commons.dbutils.handlers.BeanHandler;import org.apache.commons.dbutils.handlers.BeanListHandler;import com.hbsi.domain.User;import com.hbsi.util.DBManager;public class UserDaoImpl implements UserDao {public List<User> getAll(){try{QueryRunner runner = new QueryRunner(DBManager.getDataSource());String sql = "select * from user";return (List<User>) runner.query(sql,new BeanListHandler(User.class));}catch(Exception e){throw new RuntimeException();}}public User find(String username,String password){try{QueryRunner runner = new QueryRunner(DBManager.getDataSource());String sql = "select * from user where username=? and password=?";Object[] params = {username,password};return (User) runner.query(sql, params, new BeanHandler(User.class));}catch(Exception e){e.printStackTrace();throw new RuntimeException(e);}}public User find(String username){try{QueryRunner runner = new QueryRunner(DBManager.getDataSource());String sql = "select * from user where username=?";return (User) runner.query(sql, username, new BeanHandler(User.class));}catch(Exception e){throw new RuntimeException();}}}LoginServlet.java
package com.hbsi.servlet;import java.io.IOException;import java.io.PrintWriter;import java.security.MessageDigest;import java.security.NoSuchAlgorithmException;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 sun.misc.BASE64Encoder;import com.hbsi.dao.UserDao;import com.hbsi.dao.UserDaoImpl;import com.hbsi.domain.User;public class LoginServlet extends HttpServlet {public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {String username = request.getParameter("username");String password = request.getParameter("password");int autoLoginTime =Integer.parseInt(request.getParameter("autoLoginTime"));UserDao dao = new UserDaoImpl();User user = dao.find(username, password);if(user != null){//放到session域request.getSession().setAttribute("user",user);Cookie cookie1 = new Cookie("username",user.getUsername());Cookie cookie2 = new Cookie("password",user.getPassword());cookie1.setMaxAge(autoLoginTime);cookie2.setMaxAge(autoLoginTime);cookie1.setPath("/Filter");cookie2.setPath("/Filter");response.addCookie(cookie1);response.addCookie(cookie2);//重定向response.sendRedirect("../ChangJianYingYong/welcome.jsp");}else{request.setAttribute("message","用户名密码错");request.getRequestDispatcher("../ChangJianYingYong/message.jsp").forward(request, response);}}private String md5(String input){try {MessageDigest md = MessageDigest.getInstance("md5");byte[] result = md.digest(input.getBytes());BASE64Encoder encoder = new BASE64Encoder();return encoder.encode(result);} catch (NoSuchAlgorithmException e) {e.printStackTrace();throw new RuntimeException(e);}}public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {doGet(request, response);}}AutoLoginFilter.java
package com.hbsi.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.hbsi.dao.UserDao;import com.hbsi.dao.UserDaoImpl;import com.hbsi.domain.User;public class AutoLoginFilter implements Filter {public void destroy() {// TODO Auto-generated method stub}public void doFilter(ServletRequest request, ServletResponse response,FilterChain chain) throws IOException, ServletException {// TODO Auto-generated method stubHttpServletRequest req = (HttpServletRequest) request;HttpServletResponse resp = (HttpServletResponse) response;//1.检查用户是否登录User user = (User) req.getSession().getAttribute("user");if(user!=null){chain.doFilter(req,resp);return;}//2.检查用户是否带cookie来String username = null;String password = null;Cookie[] cookies = req.getCookies();for(int i=0;cookies!=null && i<cookies.length;i++){if(cookies[i].getName().equals("username")){username = cookies[i].getValue();}if(cookies[i].getName().equals("password")){password = cookies[i].getValue();}}if(username==null && password==null){chain.doFilter(req, resp);return;}UserDao dao = new UserDaoImpl();User user1 = dao.find(username);String save_password = user1.getPassword();if(!password.equals(save_password)){chain.doFilter(req, resp);return;}req.getSession().setAttribute("user",user1);chain.doFilter(req, resp);}public void init(FilterConfig filterConfig) throws ServletException {// TODO Auto-generated method stub}}web.xml
<?xml version="1.0" encoding="UTF-8"?><web-app version="2.5" 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_2_5.xsd"><!-- <filter><filter-name>FilterChain</filter-name><filter-class>com.hbsi.filter.FilterChain</filter-class></filter><filter-mapping><filter-name>FilterChain</filter-name><url-pattern>*.jsp</url-pattern></filter-mapping><filter><filter-name>FilterDemo1</filter-name><filter-class>com.hbsi.filter.FilterDemo1</filter-class></filter><filter-mapping><filter-name>FilterDemo1</filter-name><url-pattern>*.html</url-pattern></filter-mapping><filter><filter-name>FilterShengZhou</filter-name><filter-class>com.hbsi.filter.FilterShengZhou</filter-class><init-param><param-name>abc</param-name><param-value>aaaaa</param-value></init-param></filter><filter-mapping><filter-name>FilterShengZhou</filter-name><url-pattern>*.jsp</url-pattern></filter-mapping>--><filter><filter-name>CharseterEncodingFilter</filter-name> <filter-class>com.hbsi.filter.CharseterEncodingFilter</filter-class> <init-param> <param-name>charset</param-name> <param-value>UTF-8</param-value></init-param></filter><filter-mapping><filter-name>CharseterEncodingFilter</filter-name><url-pattern>*.jsp</url-pattern></filter-mapping><filter-mapping><filter-name>CharseterEncodingFilter</filter-name><url-pattern>/servlet/*</url-pattern></filter-mapping><filter> <filter-name>NoCahceFilter</filter-name> <filter-class>com.hbsi.filter.NoCacheFilter</filter-class> </filter><filter-mapping><filter-name>NoCahceFilter</filter-name><url-pattern>*.jsp</url-pattern></filter-mapping><filter-mapping><filter-name>NoCahceFilter</filter-name><url-pattern>/servlet/*</url-pattern></filter-mapping><filter><filter-name>ExpiresFilter</filter-name><filter-class>com.hbsi.filter.ExpiresFilter</filter-class> <init-param><param-name>css</param-name><param-value>120</param-value> </init-param><init-param><param-name>jpg</param-name><param-value>120</param-value></init-param><init-param><param-name>js</param-name><param-value>120</param-value> </init-param> </filter><filter-mapping><filter-name>ExpiresFilter</filter-name><url-pattern>*.css</url-pattern></filter-mapping><filter-mapping><filter-name>ExpiresFilter</filter-name><url-pattern>*.jpg</url-pattern></filter-mapping><filter-mapping><filter-name>ExpiresFilter</filter-name><url-pattern>*.js</url-pattern></filter-mapping> <servlet> <description>This is the description of my J2EE component</description> <display-name>This is the display name of my J2EE component</display-name> <servlet-name>LuanMaServlet</servlet-name> <servlet-class>com.hbsi.servlet.LuanMaServlet</servlet-class> </servlet> <servlet> <description>This is the description of my J2EE component</description> <display-name>This is the display name of my J2EE component</display-name> <servlet-name>LoginServlet</servlet-name> <servlet-class>com.hbsi.servlet.LoginServlet</servlet-class> </servlet> <filter> <filter-name>AutoLoginFilter</filter-name> <filter-class>com.hbsi.filter.AutoLoginFilter</filter-class> </filter> <filter-mapping> <filter-name>AutoLoginFilter</filter-name> <url-pattern>/*</url-pattern> </filter-mapping> <servlet-mapping> <servlet-name>LuanMaServlet</servlet-name> <url-pattern>/servlet/luanMa.do</url-pattern> </servlet-mapping> <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></web-app>
welcome.jsp
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html> <head> <title>My JSP 'welcome.jsp' starting page</title> </head> <body> 欢迎您：${user.username} <br> </body></html>message.jsp
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html> <head> <title>My JSP 'message.jsp' starting page</title> </head> <body> ${message}<br> </body></html>
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