使用过滤器检查当前用户是否已登录,您需要自己编写方法 userIsLoggedIn(),通过检查会话属性:
public class LoginFilter implements Filter {
public void doFilter(ServletRequest req, ServletResponse res,
FilterChain chain) throws IOException, ServletException {
if (userIsLoggedIn()) {
//process request normally, pass up the filter chain to the servlet:
chain.doFilter(req, res);
} else {
//go to login screen instead
RequestDispatcher dispatcher = getRequestDispatcher("login");
dispatcher.forward( request, response );
}
}
}
在您的 web.xml 中,您需要声明您的过滤器:
<filter>
<filter-name>loginFilter</filter-name>
<filter-class>
com.foo.LoginFilter
</filter-class>
</filter>
<filter-mapping>
<filter-name>loginFilter</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>