拦截器（二）

只拦截controller的请求, 基于aop，横切。

Spring MVC的拦截器类似于Servlet开发中的过滤器Filter，用于对处理器进行预处理和后处理。
将拦截器按一定的顺序联结成一条链，这条链称为拦截器链（InterceptorChain）。在访问被拦截的方法或字段时，
拦截器链中的拦截器就会按其之前定义的顺序被调用。拦截器也是AOP思想的具体实现。

configure xml

	<!-- 拦截器 --><mvc:interceptors><bean class="cn.bitqian.interceptor.BaseInterceptor"></bean><!-- 用户拦截器 --><mvc:interceptor>	<!-- 拦截/user的请求 -->			<mvc:mapping path="/user/**"/><mvc:exclude-mapping path="/user/login"/>	<!-- 对应实现的拦截器 -->	<bean class="cn.bitqian.interceptor.UserInterceptor"></bean></mvc:interceptor><!-- 还可以配置多个.. --></mvc:interceptors>

对登录拦截

package cn.bitqian.interceptor;import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;import org.springframework.web.servlet.ModelAndView;
import org.springframework.web.servlet.handler.HandlerInterceptorAdapter;/*** 用户拦截器* @author echo lovely**/
public class UserInterceptor extends HandlerInterceptorAdapter {@Overridepublic boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler)throws Exception {System.out.println("用户拦截器...");Object user = request.getSession().getAttribute("user");if (user == null) {response.sendRedirect("redirect:/login.jsp");return false;}return true;}@Overridepublic void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler,ModelAndView modelAndView) throws Exception {}@Overridepublic void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex)throws Exception {}}

全局拦截器，对性能分析

package cn.bitqian.interceptor;import java.util.LinkedHashMap;
import java.util.Map;import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;import org.springframework.web.servlet.ModelAndView;
import org.springframework.web.servlet.handler.HandlerInterceptorAdapter;/*** 全局拦截器* 	1. 性能监控*  2. 权限控制*  3. 日志记录* @author echo lovely**/
public class BaseInterceptor extends HandlerInterceptorAdapter {// 性能监控Map<String, Long> performanceMonitorMap = new LinkedHashMap<>();// 进入方法前@Overridepublic boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler)throws Exception {String sessionId = request.getSession().getId();long threadId = Thread.currentThread().getId();performanceMonitorMap.put(sessionId + threadId, System.currentTimeMillis());System.out.println("全局拦截器...");return true;}// 执行完方法，视图返回前@Overridepublic void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler,ModelAndView modelAndView) throws Exception {}// controller执行完，并且视图已经返回@Overridepublic void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex)throws Exception {String sessionId = request.getSession().getId();long threadId = Thread.currentThread().getId();Long start = performanceMonitorMap.get(sessionId + threadId);Long end = System.currentTimeMillis();System.out.println("该方法执行的时间：" + (end - start) * 1.0 / 1000 + "s");}
}