springboot三種過濾功能的使用與比較

若要實現對請求的過濾，有三種方式可供選擇：filter、interceptort和aop。本文主要討論三種攔截器的使用場景與使用方式。

下文中的舉例功能是計算每個請求的從開始到結束的時間，例子來源是慕課網。

一、filter

特點：可以獲取原始的ServletRequest，但無法獲取具體方法

實現：

1.繼承javax.servlet.Filter類，

2.@Component注解將其注入到框架中

3.實現其中的dofilter方法，所有的請求都會經過該方法，可以在此計算出每個請求的耗時，代碼如下：

package com.zzy.web.filter;

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 {
        // TODO Auto-generated method stub
        System.out.println("filter init");
        
    }

    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
            throws IOException, ServletException {
        // TODO Auto-generated method stub
        Long startTime = new Date().getTime();
        System.out.println("filter 請求開始時間:"+ startTime);
        chain.doFilter(request, response);
         Long endTime = new Date().getTime();
        System.out.println("filter 請求結束時間：" + endTime +",請求耗時：" + (endTime - startTime));
        
    }

    @Override
    public void destroy() {
        // TODO Auto-generated method stub
        
    }

}

注：如果有的框架沒有@Component 這個注解，可以自己寫一個配置類，在該類中指定過濾器，而且還可以指定過濾的url，配置類如下：

package com.zzy.web.config;

import static org.assertj.core.api.Assertions.failBecauseExceptionWasNotThrown;

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;

import com.zzy.web.filter.TimeFilter;
import com.zzy.web.interceptor.TimeInterceptor;

@Configuration
public class WebConfig extends WebMvcConfigurerAdapter {
    
    @Autowired
    private TimeInterceptor timeInterceptor;
    
//    @Override
//    public void addInterceptors(InterceptorRegistry registry) {
//        // TODO Auto-generated method stub
//        registry.addInterceptor(timeInterceptor);
//    }
    
    @Bean
    public FilterRegistrationBean timeFilter() {
        FilterRegistrationBean registrationBean = new FilterRegistrationBean();
        TimeFilter timeFilter = new TimeFilter();
        registrationBean.setFilter(timeFilter);
        List<String> urls = new ArrayList<>();
        urls.add("/user/*");
        registrationBean.setUrlPatterns(urls);
        return registrationBean;
    }

}

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二、interceptor

特點：可以獲取到原始的request和請求的方法，但無法獲取方法的具體參數的值。

實現：

1.繼承HandlerInterceptor接口

2.請求前的邏輯寫在prehandle（請求前調用）

3.請求后的邏輯寫在posthandle（請求成功后調用，失敗則不調用）

4.請求后，不管成功失敗都會調用aftercompletion。

5.intceptor方式繼承了之后還沒起作用，還需要在配置類里面加一下，把剛聲明的攔截器注冊一下。

代碼示例：

package com.zzy.web.interceptor;

import java.util.Arrays;
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;
@Component
public class TimeInterceptor implements HandlerInterceptor {

    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler)
            throws Exception {
        // TODO Auto-generated method stub
        System.out.println("interceptor 執行preHandle");

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

    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler,
            ModelAndView modelAndView) throws Exception {
        // TODO Auto-generated method stub
        Long startTime = Long.parseLong(request.getAttribute("startTime").toString());
        Long endTime = new Date().getTime();
        System.out.println("interceptor 執行postHandle");
        System.out.println("interceptor 請求類："+((HandlerMethod)handler).getBean().getClass().getName());
        System.out.println("interceptor 請求方法："+((HandlerMethod)handler).getMethod());
//        System.out.println("interceptor 請求參數：");
//        Arrays.asList(((HandlerMethod)handler).getMethodParameters()).stream().forEach(arg->System.out.println(arg));
        System.out.println("interceptor 請求耗時：" + (endTime - startTime));

    }

    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex)
            throws Exception {
        // TODO Auto-generated method stub
        Long startTime = Long.parseLong(request.getAttribute("startTime").toString());
        Long endTime = new Date().getTime();
        System.out.println("interceptor 執行afterCompletion");
        System.out.println("interceptor 請求類："+((HandlerMethod)handler).getBean().getClass().getName());
        System.out.println("interceptor 請求方法："+((HandlerMethod)handler).getMethod());
        System.out.println("interceptor 請求耗時：" + (endTime - startTime));
        System.out.println("interceptor 請求異常：" + ex);

    }

}

配置類如下：

package com.zzy.web.config;

import static org.assertj.core.api.Assertions.failBecauseExceptionWasNotThrown;

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;

import com.zzy.web.filter.TimeFilter;
import com.zzy.web.interceptor.TimeInterceptor;

@Configuration
public class WebConfig extends WebMvcConfigurerAdapter {
    
    @Autowired
    private TimeInterceptor timeInterceptor;
    
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        // TODO Auto-generated method stub
        registry.addInterceptor(timeInterceptor);
    }


}

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三、aop

特點：能拿到方法和具體參數的值，但是拿不到原始的servletrequest的信息。

實現：

1.使用@aspect注解

2.@execution聲明切面，聲明切面的語法可參考官網https://docs.spring.io/spring/docs/4.3.18.RELEASE/spring-framework-reference/htmlsingle/#aop-pointcuts

3.使用@Around(方法前和方法后),@Before（方法前）或@After（方法后）

以下為@Around舉例，代碼如下：

package com.zzy.web.aspect;

import java.util.Date;

import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.annotation.Around;
import org.aspectj.lang.annotation.Aspect;
import org.codehaus.jackson.map.ObjectMapper;
import org.springframework.stereotype.Component;

@Aspect
@Component
public class TimeAspect {

    @Around("execution(* com.zzy.web.controller.UserController.*(..))")
    public Object test(ProceedingJoinPoint pjp) throws Throwable {
        Long startTime = new Date().getTime();
        Object[] args = pjp.getArgs();
        for (Object arg : args) {
            System.out.println("aspect 參數：" + arg);
        }
        Object object = pjp.proceed();
        System.out.println("aspect 請求耗時：" + (new Date().getTime() - startTime));
        System.out.println("aspect 請求結果：" + new ObjectMapper().writeValueAsString(object));

        return object;

    }
}

?下圖是三種方式的攔截順序，圖片來自慕課網：

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