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;
/**
* 用于检测用户否登陆过滤器未登录则重定向指登录页面
* <p>
* 配置参数
* <p>
* checkSessionKey 需检查 Session 保存关键字<br/> redirectURL
* 用户未登录则重定向指定页面URL包括 ContextPath<br/> notCheckURLList
* 做检查URL列表分号分开并且 URL 包括 ContextPath<br/>
*/
public class LoginFilter implements Filter {

private String redirectURL = null;
private List notCheckURLList = null;
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 {
redirectURL=....
sessionKey=.....
notCheckURLList=new ArrayList();
notCheckURLList.add("登陆页面");
notCheckURLList.add("/login.jsp");
notCheckURLList.add("登陆控制器");
}
}
用修改XML文件 XML直接完全过滤
使用过滤器 初始化时候定义 过滤页面和控制器
除了登陆页面还需要过滤 登陆控制器否则...