session过期过滤器,servlet写的,应用在struts上

这一层是servlet的过滤器做的~~~

当然还是要web.xml配置一下.

  <filter>
    <filter-name>accessControl</filter-name>
    <filter-class>web.common.AccessControlFilter</filter-class>
    <init-param>
      <param-name>loginPage</param-name>
      <param-value>/usermanager/login_nasp.jsp</param-value>
    </init-param>
  </filter>
  <filter-mapping>
    <filter-name>accessControl</filter-name>
    <url-pattern>*.do</url-pattern>
  </filter-mapping>

过滤掉了所有的do的文件提交时,都会先检测一下session是否存在,是否过期.

当然要写一个servlet类,如下:

package web.common;

import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;

public class AccessControlFilter
    implements Filter {
  protected FilterConfig filterConfig;
  private String loginPage;

  public void init(FilterConfig config); throws ServletException {
    this.filterConfig = config;
    loginPage = config.getInitParameter("loginPage");;
    if (loginPage == null); {
      throw new ServletException("loginPage init param missing");;
    }
  }
  public void doFilter(final ServletRequest req, final ServletResponse
                       res, FilterChain chain); throws IOException,
      ServletException {
    HttpServletRequest hreq = (HttpServletRequest); req;
    HttpServletResponse hres = (HttpServletResponse); res;
    String isLog = (String); hreq.getSession();.getAttribute("validsession");
    if ( (isLog != null); && ( (isLog.equals("true");); || (isLog == "true"););); { //检查是否登录
      chain.doFilter(req, res);;
      return;
    }
    else
      hres.sendRedirect(loginPage);; //如果没有登录，把视图派发到登录页面
  }
  public void destroy(); {
    this.filterConfig = null;
  }

  public void setFilterConfig(final FilterConfig filterConfig); {
    this.filterConfig = filterConfig;
  }
}

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