关于访问控制问题

Question

在Filter接口的实现类doFilter中
先取session中的登录信息,没有就直接转登录页面;有向后走

Answer 1

谢谢 天堂客 。我 正在学习中，没有用过Filter，不过 查了下资料，在学习。

Answer 2

filter代码：
package ...;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.UnavailableException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;public class BackLoginExamineFilter
    implements Filter
{
    
protected String lgoninurl = null;//检查未登陆后登陆界面
protected FilterConfig filterConfig = null;
       
    public void destroy()
    {
      this.lgoninurl=null;
      this.filterConfig=null;
    }    public void doFilter(ServletRequest request, ServletResponse response,
                         FilterChain chain) throws IOException,
        ServletException
    {
     HttpServletRequest myrequest=(HttpServletRequest) request;
     HttpServletResponse myresponse=(HttpServletResponse) response;
     HttpSession session=myrequest.getSession();
     if (session.getAttribute("manguageuserid")==null)
     {
     myresponse.sendRedirect(this.lgoninurl);
     return;
     }        // Pass control on to the next filter
       chain.doFilter(request, response);    }    public void init(FilterConfig filterConfig) throws ServletException
    {       this.filterConfig=filterConfig;
       this.lgoninurl=filterConfig.getInitParameter("loginurl");    } }
web.xml中
<filter>
<description>BackLoginExamine</description>
<filter-name>BackLoginExamineFilter</filter-name>
<filter-class>包路径.BackLoginExamineFilter</filter-class>
<init-param>
<param-name>loginurl</param-name>
<param-value>登陆页面</param-value>
</init-param>
</filter>

<filter-mapping>
<filter-name>BackLoginExamineFilter</filter-name>
<url-pattern>/jsp/admin/*</url-pattern>(这里为过滤admin目录下面所有文件，注意，登陆页面不要放在本目录下面)
</filter-mapping>