拦截器是Spring中的一个概念。

1.XML配置方式

    <mvc:interceptors>
        <mvc:interceptor>
            <mvc:mapping path="/**"/>
            <mvc:exclude-mapping path="/testRequestEntity"/>
           <!-- <bean id="myInterceptor" class="xxx"></bean>-->
            <ref bean="firstInterceptor"></ref>
        </mvc:interceptor>
    </mvc:interceptors>

2.拦截器编写

//如果通过xml配置也可以
@Component
public class FirstInterceptor implements HandlerInterceptor {
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        System.err.println("FirstInterceptor的preHandler");
        return false;
    }
    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
        System.err.println("First-Posthandle");
    }
    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
        System.err.println("First-afterCompletion");
    }
}

3.执行顺序