简介

AOP意为“面向切面编程”,这样的名字并不是非常容易理解，且容易产生一些误导。AOP是新一代软件开发方式”，在Spring中提供了面向切面编程的丰富支持，允许通过分离应用的业务逻辑与系统级服务（例如审计（auditing）和事务（transaction）管理）进行内聚性的开发。应用对象只实现它们应该做的——完成业务逻辑——仅此而已。它们并不负责（甚至是意识）其它的系统级关注点，例如日志或事务支持。
AOP主要功能有日志记录，性能统计，安全控制，事务处理，异常处理。

OK，教程走起。。。。（看完保证你不再手动打印出入参了啥）

PS:本教程是基于spring boot项目讲解的

1、第一步肯定是新建项目，引入依赖啦

pom文件如下：

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.4.8</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.example</groupId>
    <artifactId>springboot-logback-async</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>springboot-logback-async</name>
    <description>Demo project for Spring Boot</description>
    <properties>
        <java.version>1.8</java.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter</artifactId>
        </dependency>
        <!-- 构建成可运行的Web项目 -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
                <!--  AOP 依赖必须加进来-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-aop</artifactId>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.20</version>
        </dependency>
        <!-- 打印日志需要 -->
        <dependency>
            <groupId>com.google.code.gson</groupId>
            <artifactId>gson</artifactId>
            <version>2.8.5</version>
        </dependency>
    </dependencies>
    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
</project>

2、新建两个实体类 UserDto、Result，代码如下：

import lombok.Data;

/**
 * body入参
 */
@Data
public class UserDto {
    private String userId;
    private String userName;
}

import lombok.AllArgsConstructor;
import lombok.Data;

/**
 * 返回对象
 * @param <T>
 */
@Data
@AllArgsConstructor
public class Result<T> {

    private static final int success = 0;
    private static final int fail = -1;

    private static final String successMsg = "请求成功";
    private static final String failMsg = "请求失败";

    private int code;
    private String message;
    private T data;
    
    public static <T> Result<T> returnSuccess(T data) {
        return new Result<T>(success, successMsg, data);
    }

    public static <T> Result<T> returnFail(T data) {
        return new Result<T>(fail, failMsg, null);
    }
}

3、新建一个测试接口类InitRest

import com.example.demo.dto.UserDto;
import com.example.demo.model.Result;
import org.springframework.web.bind.annotation.*;

//使用restful风格
@RestController
public class InitRest {
    //测试get入参
    @GetMapping("/hello")
    public Result<String> hello(@RequestParam String userId) {
        return Result.returnSuccess("Hello get...");
    }
    //测试body入参
    @PostMapping("/hello")
    public Result<UserDto> hello(@RequestBody UserDto userDto) {
        userDto.setUserId("你的名字被修改啦。。。");
        return Result.returnSuccess(userDto);
    }
}

4、关键的一步，新建一个AOP类：WebLog.java

import com.google.gson.Gson;
import lombok.extern.slf4j.Slf4j;
import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.annotation.Around;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Pointcut;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.context.request.RequestContextHolder;
import org.springframework.web.context.request.ServletRequestAttributes;
import javax.servlet.http.HttpServletRequest;
import java.util.UUID;

@Slf4j
//下面两个注解是必须的，少一个都不行哦
@Aspect
@Configuration
public class WebLog {

    //标记切入点，为指定包下的所有类的所有public方法
    @Pointcut(value = "execution(public * com.example.demo.rest.*.* (*))")
    public void webLog() {
    }

    @Around(value = "webLog()")
    public Object around(ProceedingJoinPoint joinPoint) throws Throwable {
        ServletRequestAttributes attributes = (ServletRequestAttributes) RequestContextHolder.getRequestAttributes();
        HttpServletRequest request = attributes.getRequest();
        String requestId = UUID.randomUUID().toString().replace("-", "");
        //打印入参
        log.info("requestId={},请求入参 {}", requestId, new Gson().toJson(joinPoint.getArgs()));

        Object object = joinPoint.proceed();
        //打印出参
        log.info("requestId={},请求出参 {}", requestId, new Gson().toJson(object));
        return object;
    }
}