jsp简单的登录过滤

登录后会将用户信息保存到session里
若以下过滤器检测到session的用户变量值为空则强制跳会登录页index.jsp

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;

import vo.Users;

public class LoginFilter implements Filter {

	public void destroy() {
		
	}

	public void doFilter(ServletRequest srequest, ServletResponse sresponse,
			FilterChain filterChain) throws IOException, ServletException {
		HttpServletRequest request = (HttpServletRequest) srequest;
		HttpServletResponse response = (HttpServletResponse) sresponse;
		HttpSession session = request.getSession();
		Users user = (Users) session.getAttribute("loginUser");
		if (user != null) {	
			filterChain.doFilter(srequest, sresponse);
		}
		else{
			response.sendRedirect(request.getContextPath()
					+ "/index.jsp");
		}
	}

	public void init(FilterConfig arg0) throws ServletException {
	}

}

----------配置web.xml文件----------------

		<filter>
	<filter-name>LoginFilter</filter-name>
	<filter-class>com.test.filer.LoginFilter</filter-class><!--上面文件的目录地址-->
	</filter>
	<filter-mapping>
		<filter-name>LoginFilter</filter-name>
		<url-pattern>/admin/*</url-pattern>><!--要过滤的文件所在的目录-->

	</filter-mapping>