实现拦截器拦截登录

跳转登录界面：

@RequestMapping("tologin")
	public String tologin(){
		return "login";
	}

获取用户名和密码：

@RequestMapping("loginopt")
	public String loginopt(String name,String password,HttpSession session){
		if (name!=null&&password!=null) {
			User user=service.getName(name,password);
			if (user!=null) {
				session.setAttribute("id",user.getId());
				return "list";
			}
		}
		return "login";
	}

springMVC.xml中加入拦截器

<!-- 拦截器-->
	<mvc:interceptors>
		<bean class="com.xinxin.intercept.MyIntercept" />
	</mvc:interceptors> 

拦截器：

package com.xinxin.intercept;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;

public class MyIntercept implements HandlerInterceptor{

	public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler)
			throws Exception {
		// TODO Auto-generated method stub
		String url = request.getRequestURI();
		String noInterceptor=".*/((loginopt)|(tologin)).*";
		if (url.matches(noInterceptor)) {
			return true;
		}
		Object object = request.getSession().getAttribute("id");
		if (object!=null) {
			return true;
		}
		request.getRequestDispatcher("/WEB-INF/login.jsp").forward(request, response);
		return false;
	}

	public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler,
			ModelAndView modelAndView) throws Exception {
		// TODO Auto-generated method stub
		
	}

	public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex)
			throws Exception {
		// TODO Auto-generated method stub
		
	}

}

登录界面：

<form action="loginopt.action" method="post">
        	用户名：<input type="text" name="name"/><p>
        	密码：<input type="text" name="password"/><p>
        	<input type="submit" value="登录"/><p>
        </form>