Filter、Interceptor、Aspect 区别及实现

Fliter 过滤器

请求在到达Controller之前进行与返回去之后 调用 入参为 reuqest，response，chian，过滤器获取不了具体调用哪一个类，哪一个方法。

实现：

1、继承 Filter 接口

import java.io.IOException;
import java.util.Date;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;

import org.springframework.stereotype.Component;

//@Component
public class TimeFilter implements Filter{

    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
        System.out.println("TimeFilter init");
    }

    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
            throws IOException, ServletException {
        System.out.println("TimeFilter in");
        long startTime = new Date().getTime();
        chain.doFilter(request, response);
        System.out.println("TimeFilter out 耗时：" + (new Date().getTime() - startTime));
    }

    @Override
    public void destroy() {
        System.out.println("TimeFilter destroy");
    }
}

2、声明：两种方式，一是在类前加入@Component ，不能指定拦截的路径；二是  对于SSM 在web.xml中进行声明，对于 SpringBoot 在webConfig中声明

web.xml

<filter>
    <filter-name>encodingFilter</filter-name>
    <filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
    <init-param>
      <param-name>encoding</param-name>
      <param-value>UTF-8</param-value>
    </init-param>
</filter>
<filter-mapping>
    <filter-name>encodingFilter</filter-name>
    <url-pattern>/*</url-pattern>
</filter-mapping>

SpringBoot：

package com.maple.web.config;

import java.util.ArrayList;
import java.util.List;import org.springframework.boot.web.servlet.FilterRegistrationBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;import com.maple.web.filter.TimeFilter;
import com.maple.web.interceptor.TimeInterceptor;

@Configuration
public class WebConfig{
 
    @Bean
    public FilterRegistrationBean timeFilter() {
        FilterRegistrationBean registrationBean = new FilterRegistrationBean();
        TimeFilter timeFilter = new TimeFilter();
        registrationBean.setFilter(timeFilter);
        List<String> url = new ArrayList<>();
        url.add("/*");
        registrationBean.setUrlPatterns(url);
        return registrationBean;
    }
}

Interceptor 拦截器

请求在到达Controller之前进行与返回去之后 调用 入参为 reuqest，response，handler，在过滤器之后调用，能够知道调用哪一个类，但是获取不了参数

1、继承HandlerInterceptor ，perHandler 在进入Controller前执行，若返回false则不进入Controller ，true进入Controller ，postHandler处理完Controller后进入此方法，若发生异常，则不进入postHandler。afterCompletion 都会进入此方法，无论是否发生异常都会进入。

package com.maple.web.interceptor;

import java.util.Date;

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

import org.springframework.stereotype.Component;
import org.springframework.web.method.HandlerMethod;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;

/**
 * @author hzc
 *
 */
@Component
public class TimeInterceptor implements HandlerInterceptor {

    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler)
            throws Exception {
        System.out.println("preHandle");

        System.out.println(((HandlerMethod)handler).getBean().getClass().getName());
        System.out.println(((HandlerMethod)handler).getMethod().getName());

        request.setAttribute("startTime", new Date().getTime());
        return true;
    }

    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler,
            ModelAndView modelAndView) throws Exception {
        System.out.println("postHandle");
        long startTime = (long) request.getAttribute("startTime");
        System.out.println("time interceptor 耗时： " + (new Date().getTime() - startTime));

    }

    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex)
            throws Exception {
        System.out.println("afterCompletion");
        long startTime = (long) request.getAttribute("startTime");
        System.out.println("time interceptor 耗时： " + (new Date().getTime() - startTime));
        System.out.println("ex is " + ex);
    }

}

2、声明，在SSM中需要在spring配置文件中声明，在Springboot中在Config中声明。

SSM：

<mvc:interceptors>
      <!--   对公众用户进行拦截 -->
        <mvc:interceptor>
            <mvc:mapping path="/**"/>
          <!--   拦截所有路径   -->
            <bean id="userinterceptor" class="org.sz.source.schedul.common.BaseOrgUserInterceptor">
                <property name="excludedUrls"><!-- 以下路径不拦截 -->
                   <list>
                       <value>/login.do</value>
                   </list>
                </property>
            </bean>
        </mvc:interceptor>
</mvc:interceptors>

SpringBoot：

package com.maple.web.config;

import java.util.ArrayList;
import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.web.servlet.FilterRegistrationBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;

@Configuration
public class WebConfig extends WebMvcConfigurerAdapter{

    @Autowired
    private TimeInterceptor timeInterceptor;

    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(timeInterceptor);
    }
}

Aspect 切面

使用切面，可前置增强，后置增强，环绕增强，在拦截器之后执行，可获取参数信息

1、编写切面方法类

import java.util.Date;
import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.annotation.Around;
import org.aspectj.lang.annotation.Aspect;
import org.springframework.stereotype.Component;

/**
 * @author hzc
 *
 */
@Aspect
@Component
public class TimeAspect {

    @Around("execution(* com.maple.web.controller.UserController.*(..))")
    public Object handlerControllerMethod(ProceedingJoinPoint pjp) throws Throwable {
        System.out.println("time aspect start");
        Object[] args = pjp.getArgs(); // 获取参数
        for (Object arg : args) {
            System.out.println("arg is " + arg);
        }
        long startTime = new Date().getTime();
        Object object = pjp.proceed();
        System.out.println("time aspect 耗时： " + (new Date().getTime() - startTime));
        return object;
    }
}

Filter、Interceptor、Aspect的作用范围如下：