package work; 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.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import javax.servlet.http.HttpSession; public class LoginFilter implements Filter { public void destroy() {} public void doFilter(ServletRequest request, ServletResponse response, FilterChain filterchain) throws IOException, ServletException { HttpServletRequest requ=(HttpServletRequest)request; HttpServletResponse resp=(HttpServletResponse)response; HttpSession session=requ.getSession(true); if(session.getAttribute("name")==null){ resp.sendRedirect("Login.jsp"); }else{ filterchain.doFilter(request, response); } } public void init(FilterConfig arg0) throws ServletException {} }
web.xml
<filter> <filter-name>LoginFilter</filter-name> <filter-class>work.LoginFilter</filter-class> </filter> <filter-mapping> <filter-name>LoginFilter</filter-name> <url-pattern>/Cloud.jsp</url-pattern> </filter-mapping>