java web工程，过滤器判断session失效

通常情况下，java web项目都是通过过滤器来判断session是否失效。下面做了一个例子，实现过滤器验证用户的会话是否丢失。

web.xml中的配置：

<filter><filter-name>filter</filter-name><filter-class>com.zyujie.common.LoginFilter</filter-class></filter><!-- servlet规范，不能以/*.jsp这样的结尾，写全，或者写成/app/*，这样的才行 --><filter-mapping><filter-name>filter</filter-name><url-pattern>/*</url-pattern></filter-mapping><session-config> <session-timeout>1</session-timeout></session-config>

过滤器类：

package com.zyujie.common;import java.io.IOException;import java.io.PrintWriter;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;import javax.servlet.http.HttpSession;public class LoginFilter implements Filter {public void destroy() {// TODO Auto-generated method stub}public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) throws IOException, ServletException {// TODO Auto-generated method stubHttpServletRequest request = (HttpServletRequest) req;HttpServletResponse response = (HttpServletResponse) res;HttpSession session = request.getSession();// 如果session不为空，则可以浏览其他页面String url = request.getServletPath();System.out.println(url);//这里判断目录，后缀名，当然也可以写在web.xml中，用url-pattern进行拦截映射if ((!request.getServletPath().equals("/login.action"))&& (!request.getServletPath().equals("/login.jsp"))&& (!request.getServletPath().equals("/relogin.jsp"))&& (!request.getServletPath().equals("/jquery-1.8.0.min.js"))) {System.out.println(request.getServletPath());if (session.getAttribute("userInfo") == null) {session.invalidate();response.setContentType("text/html;charset=gb2312");PrintWriter out = response.getWriter();out.println("<script language='javascript' type='text/javascript'>");out.println("alert('由于你长时间没有操作,导致Session失效!请你重新登录!');window.location.href='" + request.getContextPath() + "/relogin.jsp'");out.println("</script>");} else {chain.doFilter(request, response);}} else {chain.doFilter(request, response);}}public void init(FilterConfig arg0) throws ServletException {// TODO Auto-generated method stub}}

做了一个测试：所有的ajax请求，都不能过滤，也不知道为什么。如果ajax要进行session判断的话，可以通过拦截器：代码如下：（ajax请求不能跳转页面，不知道怎么实现这种ajax请求，session丢失，页面跳转。）

struts2配置，拦截器：

<package name="myInterceptors" namespace="/system/login" extends="struts-default"><interceptors><interceptor name="timer" class="com.zyujie.common.TimerInterceptor" /><interceptor name="logger" class="com.zyujie.common.LoggerInterceptor" /><interceptor name="sessionFilter" class="com.zyujie.common.SessionFilterInterceptor" /></interceptors><action name="userLogin" class="userLoginAction" method="userLogin">        <interceptor-ref name="logger" />        <interceptor-ref name="timer" /><result name="input" type="redirect">/login.jsp</result><result name="success" type="redirect">/ok.jsp</result>   </action>      <action name="getSession" class="userLoginAction" method="getSession">   <result name="input" type="redirect">/login.jsp</result>   </action><action name="reLogin" class="userLoginAction" method="reLogin"><result name="input" type="redirect">/relogin.jsp</result><result name="success" type="redirect">/ok.jsp</result></action><action name="testSession" class="userLoginAction" method="testSession"><interceptor-ref name="sessionFilter" /><result name="input" type="redirect">/login.jsp</result><result name="success" type="redirect">/ok.jsp</result></action></package>

拦截类：

package com.zyujie.common;import java.io.PrintWriter;import javax.servlet.http.HttpServletResponse;import javax.servlet.http.HttpSession;import org.apache.struts2.ServletActionContext;import com.opensymphony.xwork2.Action;import com.opensymphony.xwork2.ActionInvocation;import com.opensymphony.xwork2.interceptor.AbstractInterceptor;public class SessionFilterInterceptor extends AbstractInterceptor {@Overridepublic String intercept(ActionInvocation invocation) throws Exception {HttpSession session = ServletActionContext.getRequest().getSession();if(session.getAttribute("userInfo") == null){//HttpServletResponse response = ServletActionContext.getResponse();//ServletActionContext.getResponse().sendRedirect(Action.INPUT);//session.invalidate();//response.setContentType("text/html;charset=gb2312");//PrintWriter out = response.getWriter();//out.println("<script language='javascript' type='text/javascript'>");//out.println("alert('由于你长时间没有操作,导致Session失效!请你重新登录!');window.location.href='/login.jsp'");//out.println("</script>");//return "none";return Action.INPUT;}else{return invocation.invoke();}}}

对于ajax的请求，不能跳转页面。很多人说的，还是只有在页面端判断返回值，进行跳转。