springmvc 自定义拦截器

<mvc:interceptors>
        <!-- 配置自定义的拦截器 -->
        <bean class="com.atguigu.springmvc.interceptors.FirstInterceptor"></bean>
        
</mvc:interceptors>

<mvc:interceptors>
        <!-- 配置自定义的拦截器 -->
        <bean class="com.atguigu.springmvc.interceptors.FirstInterceptor"></bean>
        
        <!-- 配置拦截器(不)作用的路径 -->
        <mvc:interceptor>
            <mvc:mapping path="/emps"/>
            <bean class="com.atguigu.springmvc.interceptors.SecondInterceptor"></bean>
        </mvc:interceptor>
        
</mvc:interceptors>

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

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

public class FirstInterceptor implements HandlerInterceptor{

    /**
     * 该方法在目标方法之前被调用.
     * 若返回值为 true, 则继续调用后续的拦截器和目标方法. 
     * 若返回值为 false, 则不会再调用后续的拦截器和目标方法. 
     * 
     * 可以考虑做权限. 日志, 事务等. 
     */
    @Override
    public boolean preHandle(HttpServletRequest request,
            HttpServletResponse response, Object handler) throws Exception {
        System.out.println("[FirstInterceptor] preHandle");
        return true;
    }

    /**
     * 调用目标方法之后, 但渲染视图之前. 
     * 可以对请求域中的属性或视图做出修改. 
     */
    @Override
    public void postHandle(HttpServletRequest request,
            HttpServletResponse response, Object handler,
            ModelAndView modelAndView) throws Exception {
        System.out.println("[FirstInterceptor] postHandle");
    }

    /**
     * 渲染视图之后被调用. 释放资源
     */
    @Override
    public void afterCompletion(HttpServletRequest request,
            HttpServletResponse response, Object handler, Exception ex)
            throws Exception {
        System.out.println("[FirstInterceptor] afterCompletion");
    }

}

preHandle按顺序的正序执行
postHandle、afterCompletion按顺序的反序执行