session到时间后自动失效。可以在过滤器中写,也可以写一个包含文件,在这个包含文件中判断session的某个属性是否为空,为空则调至登录页面。这个比较简单。
下面是一个过滤器。import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.util.List;
import java.util.ArrayList;
import java.util.StringTokenizer;
import java.io.IOException; /** *//**
* 用于检测用户是否登陆的过滤器,如果未登录,则重定向到指的登录页面
* 配置参数
* checkSessionKey 需检查的在 Session 中保存的关键字 * redirectURL 如果用户未登录,则重定向到指定的页面,URL不包括 ContextPath * notCheckURLList 不做检查的URL列表,以分号分开,并且 URL 中不包括 ContextPath */
public class CheckLoginFilter
implements Filter
{
protected FilterConfig filterConfig = null;
private String redirectURL = null;
private List notCheckURLList = new ArrayList();
private String sessionKey = null; public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException
{
HttpServletRequest request = (HttpServletRequest) servletRequest;
HttpServletResponse response = (HttpServletResponse) servletResponse; HttpSession session = request.getSession();
if(sessionKey == null)
{
filterChain.doFilter(request, response);
return;
}
if((!checkRequestURIIntNotFilterList(request)) && session.getAttribute(sessionKey) == null)
{
response.sendRedirect(request.getContextPath() + redirectURL);
return;
}
filterChain.doFilter(servletRequest, servletResponse);
} public void destroy()
{
notCheckURLList.clear();
} private boolean checkRequestURIIntNotFilterList(HttpServletRequest request)
{
String uri = request.getServletPath() + (request.getPathInfo() == null ? "" : request.getPathInfo());
return notCheckURLList.contains(uri);
} public void init(FilterConfig filterConfig) throws ServletException
{
this.filterConfig = filterConfig;
redirectURL = filterConfig.getInitParameter("redirectURL");
sessionKey = filterConfig.getInitParameter("checkSessionKey"); String notCheckURLListStr = filterConfig.getInitParameter("notCheckURLList"); if(notCheckURLListStr != null)
{
StringTokenizer st = new StringTokenizer(notCheckURLListStr, ";");
notCheckURLList.clear();
while(st.hasMoreTokens())
{
notCheckURLList.add(st.nextToken());
}
}
}
}
下面是一个过滤器。import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.util.List;
import java.util.ArrayList;
import java.util.StringTokenizer;
import java.io.IOException; /** *//**
* 用于检测用户是否登陆的过滤器,如果未登录,则重定向到指的登录页面
* 配置参数
* checkSessionKey 需检查的在 Session 中保存的关键字 * redirectURL 如果用户未登录,则重定向到指定的页面,URL不包括 ContextPath * notCheckURLList 不做检查的URL列表,以分号分开,并且 URL 中不包括 ContextPath */
public class CheckLoginFilter
implements Filter
{
protected FilterConfig filterConfig = null;
private String redirectURL = null;
private List notCheckURLList = new ArrayList();
private String sessionKey = null; public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException
{
HttpServletRequest request = (HttpServletRequest) servletRequest;
HttpServletResponse response = (HttpServletResponse) servletResponse; HttpSession session = request.getSession();
if(sessionKey == null)
{
filterChain.doFilter(request, response);
return;
}
if((!checkRequestURIIntNotFilterList(request)) && session.getAttribute(sessionKey) == null)
{
response.sendRedirect(request.getContextPath() + redirectURL);
return;
}
filterChain.doFilter(servletRequest, servletResponse);
} public void destroy()
{
notCheckURLList.clear();
} private boolean checkRequestURIIntNotFilterList(HttpServletRequest request)
{
String uri = request.getServletPath() + (request.getPathInfo() == null ? "" : request.getPathInfo());
return notCheckURLList.contains(uri);
} public void init(FilterConfig filterConfig) throws ServletException
{
this.filterConfig = filterConfig;
redirectURL = filterConfig.getInitParameter("redirectURL");
sessionKey = filterConfig.getInitParameter("checkSessionKey"); String notCheckURLListStr = filterConfig.getInitParameter("notCheckURLList"); if(notCheckURLListStr != null)
{
StringTokenizer st = new StringTokenizer(notCheckURLListStr, ";");
notCheckURLList.clear();
while(st.hasMoreTokens())
{
notCheckURLList.add(st.nextToken());
}
}
}
}
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import java.io.IOException;
import javax.servlet.Filter;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.ServletException;
import javax.servlet.FilterConfig;
import javax.servlet.http.HttpSession;public class SignonFilter implements Filter
{
String LOGIN_PAGE="login_signon.jsp";
protected FilterConfig filterConfig;
//过滤处理的方法
public void doFilter(final ServletRequest req,final ServletResponse res,FilterChain chain)throws IOException,ServletException
{
HttpServletRequest hreq = (HttpServletRequest)req;
HttpServletResponse hres = (HttpServletResponse)res;
HttpSession session = hreq.getSession();
String isLogin="";
try
{
isLogin=(String)session.getAttribute("isLogin");
if(isLogin.equals("true"))
{
System.out.println("在SignonFilter中验证通过");
//验证成功,继续处理
chain.doFilter(req,res);
}
else
{
//验证不成功,让用户登录。
hres.sendRedirect(LOGIN_PAGE);
System.out.println("被SignonFilter拦截一个未认证的请求");
}
}
catch(Exception e)
{
e.printStackTrace();
}
}
public void setFilterConfig(final FilterConfig filterConfig)
{
this.filterConfig=filterConfig;
}
//销毁过滤器
public void destroy()
{
this.filterConfig=null;
}
/**
*初始化过滤器,和一般的Servlet一样,它也可以获得初始参数。
*/
public void init(FilterConfig config) throws ServletException {
this.filterConfig = config;
}
}
<filter-name>auth</filter-name>
<filter-class>test.SignonFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>auth</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>