手把手教學切面編程實戰之Spring AOP基于注解實作

理論是實踐的基礎，實踐是檢驗真理的唯一標準

一、快速入門指引（所見即所得）

• Spring AOP核心概念

• 在我們開始使用AOP之前，我們先熟悉AOP概念和術語，這些術語并非特定于Spring，而是與AOP相關，理解這些概念和術語非常有助于理解本文，

• 切面在專案中應用場景

二、核心業務場景實戰之 "記錄業務操作行為"

• 快速上手的核心步驟

1. SpringBoot啟動類開啟AOP：@EnableAspectJAutoProxy(proxyTargetClass = true)
2. 定義切面注解類：ArticleOperational
3. 定義切面核心類：ArticleContentAspect
4. 在核心業務中使用切面注解：@ArticleOperational(action = "取消置頂")

• SpringBoot啟動類開啟Aop

package com.demo.content;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.EnableAspectJAutoProxy;

/**
 * @author youyun.xu
 * @ClassName: ContentApplication
 * @Description: 內容管理微服務
 * @date 2020/7/23 上午09:00
 */
@SpringBootApplication(scanBasePackages = "com.demo")
@EnableAspectJAutoProxy(proxyTargetClass = true)
public class ContentApplication {

    public static void main(String[] args) {
        SpringApplication.run(ContentApplication.class, args);
    }
}

• 定義切面注解類

package com.demo.annotation;

import java.lang.annotation.*;

/**
 * @author youyun.xu
 * @ClassName: ArticleOperational
 * @Description: 切面管理檔案操作注解
 * @date 2020/7/23 上午09:00
 */
@Target({ElementType.TYPE,ElementType.METHOD,ElementType.PARAMETER})
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface ArticleOperational {

    String action() default "";
}

• 定義切面核心類

package com.demo.aop;

import com.alibaba.fastjson.JSON;
import com.demo.annotation.ArticleOperational;
import org.aspectj.lang.JoinPoint;
import org.aspectj.lang.annotation.AfterReturning;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Pointcut;
import org.aspectj.lang.reflect.MethodSignature;
import org.springframework.core.DefaultParameterNameDiscoverer;
import org.springframework.core.ParameterNameDiscoverer;
import org.springframework.stereotype.Component;
import org.springframework.web.context.request.RequestContextHolder;
import org.springframework.web.context.request.ServletRequestAttributes;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.lang.reflect.Method;
import java.util.HashMap;
import java.util.Map;

/**
 * @author youyun.xu
 * @ClassName: ArticleContentAspect
 * @Description: 切面監控文章操作狀態
 * @date 2020/7/23 上午09:00
 */
@Aspect
@Component
public class ArticleContentAspect{

    // 定義切入點
    @Pointcut("@annotation(com.tcl.uf.content.annotation.ArticleOperational)")
    public void operational() {}

    /**
     * 獲取引數串列
     * @param joinPoint
     * @return
     * @throws ClassNotFoundException
     * @throws NoSuchMethodException
     */
    private static Map<String, Object> getFieldsName(JoinPoint joinPoint) {
        Object[] args = joinPoint.getArgs();
        ParameterNameDiscoverer pnd = new DefaultParameterNameDiscoverer();
        MethodSignature signature = (MethodSignature) joinPoint.getSignature();
        Method method = signature.getMethod();
        String[] parameterNames = pnd.getParameterNames(method);
        Map<String, Object> paramMap = new HashMap<String, Object>();
        for (int i = 0; i < parameterNames.length; i++) {
            paramMap.put(parameterNames[i], args[i]);
        }
        return paramMap;
    }

    @AfterReturning(value = "operational()")
    public void p1(JoinPoint joinPoint){
        //HttpServletRequest 和 HttpServletResponse 物件(示例)
        ServletRequestAttributes attributes = (ServletRequestAttributes) RequestContextHolder.getRequestAttributes();
        HttpServletRequest request = attributes.getRequest();
        HttpServletResponse response = attributes.getResponse();
        User user = getUserInfo(request);
        //獲取請求引數和值(示例)
        Map<String,Object> params = getFieldsName(joinPoint);
        MethodSignature signature = (MethodSignature) joinPoint.getSignature();
        Method method = signature.getMethod();
        //獲取注解資訊(示例)
        ArticleOperational articleOperational= method.getDeclaredAnnotation(ArticleOperational.class);
        //持久化操作日志
        saveArticleOperationalRecord(articleOperational.action(),user.getUserId(),JSON.toJSONString(params));
    }

    private void saveArticleOperationalRecord(String operational,String userId,String remarks){
        //持久化操作記錄到資料庫
    }

    private User getUserInfo(HttpServletRequest request){
        //我此處寫的是偽代碼、僅供參考
        return new User("youyun.xu","13246738031");
    }
}

• 業務使用AOP切面注解

package com.demo.service.impl;

import com.demo.annotation.ArticleOperational;
import com.demo.service.ArticleContentService;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import java.util.List;

/**
 * @author youyun.xu
 * @ClassName: ArticleContentServiceImpl
 * @Description: 文章內容服務Service
 * @date 2020/7/23 上午09:00
 */
@Service("articleContentService")
public class ArticleContentServiceImpl implements ArticleContentService {

    private static final Logger log = LoggerFactory.getLogger(ArticleContentServiceImpl.class);

    @Override
    @Transactional(rollbackFor = Exception.class)
    @ArticleOperational(action = "取消置頂")
    public void cancelArticleTop(Long articleId) {
        //取消置頂業務核心代碼
    }

    @Override
    @Transactional(rollbackFor = Exception.class)
    @ArticleOperational(action = "洗掉文章")
    public void delete(List<Long> articleIds) {
        //洗掉文章業務核心代碼
    }

    @Override
    @Transactional(rollbackFor = Exception.class)
    @ArticleOperational(action = "文章下線")
    public void offline(List<Long> articleIds) {
        //文章下線業務核心代碼
    }

    @Override
    @Transactional(rollbackFor = Exception.class)
    @ArticleOperational(action = "文章發布")
    public void publish(List<Long> articleIds) {
        //文章發布業務核心代碼
    }
}

在核心業務代碼的函式上添加自定義注解 @ArticleOperational(action = "洗掉文章") 即可，

• 小結

1. 高效、靈活、對代碼無任何侵入性
2. 減少大量冗余代碼、代碼可讀性更好
3. 原創不易，你如果喜歡請給幫我反手點個贊，

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