Struts2使用过滤器验证登陆状态

在Web.xml中增加个配置过滤器loginFilter：

<filter>
<filter-name>loginFilter</filter-name>
<filter-class>com.filter.LoginFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>loginFilter</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>

在处理登陆的action中,登陆成功后,往session中写入一个值,作为是否登陆的标记,这里写入用户名username:

1 HttpServletRequest request = ServletActionContext.getRequest();
2 request.getSession().setAttribute("username", username);

然后编辑相应的过滤器类LoginFilter,过滤器检查session中username的值是否为空,为空则跳转至登陆页面：

package com.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.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

public class LoginFilter extends HttpServlet implements Filter {
public void destroy() {
}

public void doFilter(ServletRequest sRequest, ServletResponse sResponse,
FilterChain filterChain) throws IOException, ServletException{

HttpServletRequest request = (HttpServletRequest) sRequest;
HttpServletResponse response = (HttpServletResponse) sResponse;
HttpSession session = request.getSession();
String url=request.getServletPath();
String contextPath=request.getContextPath();
if(url.equals("")) url+="/";
if((url.startsWith("/")&&!url.startsWith("/login"))){//若访问后台资源 过滤到login
String user=(String)session.getAttribute("username");
if(user==null){//转入管理员登陆页面
response.sendRedirect(contextPath+"/login.jsp");
return;
}
}
filterChain.doFilter(sRequest, sResponse);
}

public void init(FilterConfig arg0) throws ServletException {

}
}

这样就可以了,除了login页面外全部都会被过滤器检测。

注：

浏览器关闭后session将被销毁，用户需重新登陆。

退出操作则将session中的username值设置为null即可。
文章来源：http://www.cnblogs.com/myfjd/archive/2011/11/25/2263699.html