zoukankan      html  css  js  c++  java
  • SpingMVC之拦截器

    Spring Web MVC的处理器拦截器  双向  request  response

    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。

    拦截器拦截的请求是建立在前端控制器配置之下的,若DispatcherServlet拦截的是*.action,则拦截器即使配置 /**,则拦截器拦截的也只是所有 *.action的请求。若DispatcherServlet拦截的是 /,则拦截器配置 /**才是拦截所有资源。

    preHandle预处理回调方法,实现处理器的预处理(如登录检查),第三个参数为响应的处理器(如我们上一章的Controller实现);

               返回值:true表示继续流程(如调用下一个拦截器或处理器);

                         false表示流程中断(如登录检查失败),不会继续调用其他的拦截器或处理器,此时我们需要通过response来产生响应;

    postHandle后处理回调方法,实现处理器的后处理(但在渲染视图之前),此时我们可以通过modelAndView(模型和视图对象)对模型数据进行处理或对视图进行处理,modelAndView也可能为null。

    afterCompletion整个请求处理完毕回调方法,即在视图渲染完毕时回调,如性能监控中我们可以在此记录结束时间并输出消耗时间,还可以进行一些资源清理,类似于try-catch-finally中的finally,但仅调用处理器执行链中preHandle返回true的拦截器的afterCompletion

    下边是springMVC的拦截器实现

    一.定义拦截器 (单个拦截器) 实现HandlerInterceptor 

    拦截器
     */
    public class Intecptor implements HandlerInterceptor {
    
        public boolean preHandle(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o) throws Exception {
            System.out.println("preHandle====");
    //这里如果返回的是false 则不执行拦截器其他的方法 如果是true 则进入另外两个方法
    return true; } public void postHandle(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o, ModelAndView modelAndView) throws Exception { System.out.println("postHandle===="); } public void afterCompletion(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o, Exception e) throws Exception { System.out.println("afterCompletion===="); } }

    二.xml配置  记得加注解驱动

    <!--包扫描器-->
        <context:component-scan base-package="day17"></context:component-scan>
    
        <!--视图解析器-->
      <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
            <property name="prefix" value="/"></property>
            <property name="suffix" value=".jsp"></property>
        </bean>
    
        <!--单个拦截器-->
        <mvc:interceptors>
          <mvc:interceptor>
              <mvc:mapping path="/**"/>
              <bean class=" day17.Intecptor"/>
          </mvc:interceptor>
        </mvc:interceptors>

    定义多个拦截器

    拦截器1

    /*
    拦截器
     */
    public class Intecptor implements HandlerInterceptor {
    
        public boolean preHandle(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o) throws Exception {
            System.out.println("preHandle====");
            return true;
        }
    
        public void postHandle(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o, ModelAndView modelAndView) throws Exception {
            System.out.println("postHandle====");
        }
    
        public void afterCompletion(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o, Exception e) throws Exception {
            System.out.println("afterCompletion====");
        }
    }

    拦截器2

    public class Intecptors implements HandlerInterceptor {
        public boolean preHandle(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o) throws Exception {
            System.out.println("Second preHandle====");
            return true;
        }
        public void postHandle(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o, ModelAndView modelAndView) throws Exception {
            System.out.println("Second postHandle====");
        }
    
        public void afterCompletion(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o, Exception e) throws Exception {
            System.out.println("Second afterCompletion====");
        }
    }

    xml配置

    <!--包扫描器-->
        <context:component-scan base-package="day17"></context:component-scan>
    
        <!--视图解析器-->
      <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
            <property name="prefix" value="/"></property>
            <property name="suffix" value=".jsp"></property>
        </bean>
       
        <!--多个拦截器-->
      <!--  <mvc:interceptors>
            <mvc:interceptor>
            <mvc:mapping path="/**"/>
            <bean class=" day17.Intecptor"/>
        </mvc:interceptor>
            <mvc:interceptor>
                <mvc:mapping path="/**"/>
                <bean class=" day17.Intecptors"/>
            </mvc:interceptor>
        </mvc:interceptors>-->
        <!--注解驱动-->
    <mvc:annotation-driven></mvc:annotation-driven>
            </beans>
  • 相关阅读:
    UVA 1400."Ray, Pass me the dishes!" -分治+线段树区间合并(常规操作+维护端点)并输出最优的区间的左右端点-(洛谷 小白逛公园 升级版)
    SPOJ GSS3-Can you answer these queries III-分治+线段树区间合并
    洛谷 P4513 小白逛公园-区间最大子段和-分治+线段树区间合并(单点更新、区间查询)
    HDU 3074.Multiply game-区间乘法-线段树(单点更新、区间查询),上推标记取模
    HDU 3183.A Magic Lamp-区间找最小值-RMQ(ST)
    HDU 1231.最大连续子序列-dp+位置标记
    牛客网 牛客练习赛43 F.Tachibana Kanade Loves Game-容斥(二进制枚举)+读入挂
    CodeForce-811B Vladik and Complicated Book(水题)
    POJ1426——Find The Multiple (简单搜索+取余)
    POJ——3278 Catch That Cow(BFS队列)
  • 原文地址:https://www.cnblogs.com/1234AAA/p/8694306.html
Copyright © 2011-2022 走看看