<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-aop</artifactId>
</dependency>

import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Pointcut;
import org.aspectj.lang.annotation.Before;
import org.springframework.stereotype.Component;

@Aspect     // 聲明這是一個(gè)切面類
@Component // 讓Spring容器接管
public class LoggingAspect {

    // 定義切點(diǎn)，攔截com.example包及其子包下的所有方法
    @Pointcut("within(com.example..*)")
    public void loggable() {}

    // 定義一個(gè)前置通知
    @Before("loggable()")
    public void beforeAdvice() {
        System.out.println("Before the method is called");
    }
    
    ```
//	方法正常執(zhí)行完之后
    /**
     * 在程序正常執(zhí)行完之后如果有返回值，我們可以對(duì)這個(gè)返回值進(jìn)行接收
     * returning用來(lái)接收方法的返回值
     * */
    @AfterReturning("loggable()",returning="result")
    public void LogReturn(JoinPoint joinPoint,Object result) {
		System.out.println("【" + joinPoint.getSignature().getName() + "】程序方法執(zhí)行完畢了...結(jié)果是：" + result);
	}
}

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

@SpringBootApplication
@EnableAspectJAutoProxy
public class MyApp {
    public static void main(String[] args) {
        SpringApplication.run(MyApp.class, args);
    }
}

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

@Target({ElementType.METHOD}) // 這個(gè)注解只能應(yīng)用至方法上
@Retention(RetentionPolicy.RUNTIME) // 運(yùn)行時(shí)還會(huì)保留這個(gè)注解
public @interface Loggable { 
}

import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Pointcut;
import org.aspectj.lang.annotation.Before;
import org.aspectj.lang.JoinPoint;
import org.aspectj.lang.reflect.MethodSignature;
import org.springframework.stereotype.Component;

@Aspect
@Component
public class LoggingAspect {

    // 定義切點(diǎn)，匹配所有標(biāo)記了@Loggable注解的方法
    @Pointcut("@annotation(com.example.Loggable)")
    public void loggable() {}

    // 定義一個(gè)前置通知
    @Before("loggable()")
    public void beforeAdvice(JoinPoint joinPoint) {
        // 這里利用了JAVA反射的特性
        MethodSignature signature = (MethodSignature) joinPoint.getSignature();
        Loggable loggable = signature.getMethod().getAnnotation(Loggable.class);
        if (loggable != null) {
            System.out.println("Before method: " + joinPoint.getSignature().getName() + " - " + loggable);
        }
    }
}

import com.example.Loggable;
import org.springframework.stereotype.Service;

@Service
public class MyService {

    @Loggable
    public void someMethod() {
        System.out.println("Executing someMethod");
    }
}

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

@SpringBootApplication
@EnableAspectJAutoProxy
public class MyApp {
    public static void main(String[] args) {
        SpringApplication.run(MyApp.class, args);
    }
}