Spring MVC 拦截请求 实现简单的登录验证

springmvc拦截器的配置、使用：
自定义拦截器，实现HandlerInterceptor接口。

配置mvc.xml

    	<mvc:interceptors>
		<!-- 使用bean定义一个Interceptor，直接定义在mvc:interceptors根下面的Interceptor将拦截所有的请求 -->
		<mvc:interceptor>
			<!-- 进行拦截：/**表示拦截所有controller -->
			<mvc:mapping path="/login/**" />
			<bean class="com.gcsoft.web.login.Login" />
		</mvc:interceptor>
	</mvc:interceptors>

java:

package com.gcsoft.web.login;

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

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

import cn.gcsoft.cons.CommonConstant;
import cn.gcsoft.model.User;

public class Login implements HandlerInterceptor {

	@Override
	public void afterCompletion(HttpServletRequest httpRequest, HttpServletResponse httpResponse, Object arg2,
			Exception arg3) throws Exception {

	}

	@Override
	public void postHandle(HttpServletRequest arg0, HttpServletResponse arg1, Object arg2, ModelAndView arg3)
			throws Exception {

	}

	@Override
	public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object object) throws Exception {
		String urlString = request.getRequestURI();
		String contextPath = request.getContextPath();
		User user = (User) request.getSession().getAttribute(CommonConstant.USER_CONTEXT);
		if (!urlString.endsWith("doLogin.action")) {
			if (user == null) {
				response.sendRedirect(contextPath + "/login/doLogin.action");
				return true;
			}
		}
		return true;
	}

}