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 EncodingFilter implements Filter {private String charSet;//字符编码
@Overridepublic void destroy() {System.out.println("过滤器已销毁...");}@Overridepublic void doFilter(ServletRequest req, ServletResponse resp, FilterChain chain) throws IOException,ServletException {// 执行过滤System.out.println("执行过滤之前：doFilter()");req.setCharacterEncoding(this.charSet); //统一设置编码
chain.doFilter(req, resp);//请求继续传递System.out.println("执行过滤之后：doFilter()");}/*** 在容器启动的时候自动加载，通过getInitParameter()获取配置的初始化参数，只初始化一次。*/@Overridepublic void init(FilterConfig config) throws ServletException {String initParam = config.getInitParameter("encoding");//获取初始化参数this.sharSet = initParam ;System.out.println("过滤器初始化，初始化参数是：" + initParam);}
}

<filter><filter-name>encodingFilter</filter-name><filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class><init-param><param-name>encoding</param-name><param-value>UTF-8</param-value></init-param><init-param><param-name>forceEncoding</param-name><param-value>true</param-value></init-param>
</filter>
<filter-mapping><filter-name>encodingFilter</filter-name><url-pattern>/*</url-pattern>
</filter-mapping><filter-mapping><filter-name>encodingFilter</filter-name><url-pattern>/jsp/*</url-pattern>
</filter-mapping>

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.HttpSession;public class LoginFilter implements Filter {@Overridepublic void destroy() {}/*** session本身属于HTTP协议的范畴，doFilter()定义的是ServletRequest，* 要想获取session，必须进行向下转型：ServletRequest改成HttpServletRequest,才能使用getSession()获取session对象。*/@Overridepublic void doFilter(ServletRequest req, ServletResponse resp, FilterChain chain) throws IOException,ServletException {HttpServletRequest hsp = (HttpServletRequest)req;//向下转型HttpSession ss = hsp.getSession();if(ss.getAttribute("userId") != null){ //判断用户是否登录
　　　　　　chain.doFilter(req, resp);}else{req.getRequestDispatcher("login.jsp").forward(req, resp); //跳转到登录页面
　　　　}}@Overridepublic void init(FilterConfig arg0) throws ServletException {}
}

import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;//对上下文状态的监听public class ServletContextListenner implements ServletContextListener {@Overridepublic void contextDestroyed(ServletContextEvent event) {//上下文销毁触发System.out.println("容器销毁" + event.getServletContext().getContextPath());}@Overridepublic void contextInitialized(ServletContextEvent event) {//上下文初始化触发System.out.println("容器初始化"+ event.getServletContext().getContextPath());}
}

<listener><listener-class>com.mxzer.common.listener.ServletContextListenner</listener-class>
</listener>

　　　　<!-- session 失效时间 单位30分钟 --><session-config><session-timeout>30</session-timeout></session-config>

/**
* 使用HttpSessionBindingListener
* session属性监听：不需要在web.xml中配置
*
*/
public class ServletContextListenner implements HttpSessionBindingListener {private String loginName; //登录名public ServletContextListenner(String loginName) {this.loginName = loginName;}public String getLoginName() {return loginName;}public void setLoginName(String loginName) {this.loginName = loginName;}@Overridepublic void valueBound(HttpSessionBindingEvent event) {System.out.println("在session中保存登录对象" + this.getLoginName()+"session ID:"+event.getSession().getId());}@Overridepublic void valueUnbound(HttpSessionBindingEvent event) {System.out.println("在session中移除登录对象" + this.getLoginName()+"session ID:"+event.getSession().getId());}}

    System.out.println("request请求初始化" +"http://"+ event.getServletRequest().getRomoteAddr());System.out.println("request请求初始化" +"http://"+ event.getServletContext().getContextPath());

System.out.println(event.getNmae() + event.getValue());