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 stub
HttpServletRequest 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 {

@Override
public 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。