springmvc可以使用拦截器对请求进行拦截处理，用户可以自定义拦截器来实现特定功能

自定义拦截器必须实现HandlerInterceptor接口

-preHandle():这个方法在业务处理器处理请求之前被调用，在该方法中对用户请求request

进行处理。如果你决定该拦截器对请求进行拦截处理后还要调用其他拦截器，或者业务处理器

去进行处理，则返回true；如果你决定不需要再调用其他组件处理请求，则返回false

-postHandle():这个方法在业务处理器处理完请求后，但是DispatchServlet向客户端返回

响应前被调用，在该方法中对用户请求request进行处理

-afterCompletion():这个方法在DispatchServlet完全处理完请求后被调用，可以在该方法中

进行一些资源清理操作

多个拦截器执行顺序

package com.hous.crud.interceptor;

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 arg0, HttpServletResponse arg1, Object arg2) throws Exception {
System.out.println("[FirstInterceptor]preHandle");
return true;
}

/*
* 调用目标方法之后，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 arg2, ModelAndView mv)
throws Exception {
//		System.out.println(mv.getViewName());
System.out.println(request.getRequestURI());
System.out.println("[FirstInterceptor]postHandle");
}

/*
* 渲染视图之后被调用，释放资源
*/
@Override
public void afterCompletion(HttpServletRequest arg0, HttpServletResponse arg1, Object arg2, Exception arg3)
throws Exception {
System.out.println("[FirstInterceptor]afterCompletion");
}
}

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:context="http://www.springframework.org/schema/context"
xmlns:mvc="http://www.springframework.org/schema/mvc"
xmlns:aop="http://www.springframework.org/schema/aop"
xsi:schemaLocation="http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-4.2.xsd
http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-4.2.xsd
http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.2.xsd">

<!-- 自动扫描bean -->
<context:component-scan base-package="com.hous.crud"></context:component-scan>
<!-- 配置视图解析器 -->
<bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
<property name="prefix" value="/WEB-INF/views/"></property>
<property name="suffix" value=".jsp"></property>
</bean>
<!-- 解决静态资源路径问题 -->
<mvc:default-servlet-handler/>

<mvc:annotation-driven conversion-service="conversionService"/>
<!--
将自定义的转换器注册到springmvc上下文中
org.springframework.context.support.ConversionServiceFactoryBean
org.springframework.format.support.FormattingConversionServiceFactoryBean
-->
<bean id="conversionService" class="org.springframework.format.support.FormattingConversionServiceFactoryBean">
<property name="converters">
<set>
<ref bean="employeeConverter"/>
</set>
</property>
</bean>
<!-- 配置国际化 -->
<bean id="messageSource"
class="org.springframework.context.support.ResourceBundleMessageSource">
<property name="basename" value="i18n"></property>
</bean>
<!-- 配置SessionLocaleResolver -->
<bean id="localeResolver"
class="org.springframework.web.servlet.i18n.SessionLocaleResolver"></bean>
<mvc:interceptors>
<!-- 配置自定义拦截器 -->
<bean class="com.hous.crud.interceptor.FirstInterceptor" />
<!-- 配置LocaleChangeInterceptor -->
<bean class="org.springframework.web.servlet.i18n.LocaleChangeInterceptor" />
<mvc:interceptor>
<mvc:mapping path="/json"/>
<bean class="com.hous.crud.interceptor.SecondInterceptor" />
</mvc:interceptor>
</mvc:interceptors>
<!--
<mvc:view-controller path="/i18n"/>
-->
<mvc:view-controller path="/i18n2"/>

<!-- 文件上传解析器 -->
<bean id="multipartResolver"
class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
<property name="defaultEncoding" value="UTF-8"></property>
<property name="maxUploadSize" value="1024000"></property>
</bean>

</beans>

package com.hous.crud.interceptor;

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

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

public class SecondInterceptor 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 arg0, HttpServletResponse arg1, Object arg2) throws Exception {
System.out.println("[SecondInterceptor]preHandle");
return true;
}

/*
* 调用目标方法之后，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 arg2, ModelAndView mv)
throws Exception {
//		System.out.println(mv.getViewName());
System.out.println(request.getRequestURI());
System.out.println("[SecondInterceptor]postHandle");
}

/*
* 渲染视图之后被调用，释放资源
*/
@Override
public void afterCompletion(HttpServletRequest arg0, HttpServletResponse arg1, Object arg2, Exception arg3)
throws Exception {
System.out.println("[SecondInterceptor]afterCompletion");
}
}