Custom annotation not being called

Question

I'm trying to time methods via annotations, I've found plenty of information about how to time executions of things, and I feel like I'm close but my console isn't getting any output.

The jist of what I'm trying to do

    public static void main(String[] args) {
        Simpleton simp = new Simpleton();
        simp.howLongDidThisTake();
    }

    @MethodTimer
    public void howLongDidThisTake() {
        try {
            Thread.sleep(50);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }

My Interface

package com.lixar.apba.aop.annotations;

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

@Target(ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
public @interface MethodTimer{
}

and my advice/service class for the functionality attached to it.

package com.lixar.apba.aop.annotations;

import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.annotation.Around;
import org.aspectj.lang.annotation.Aspect;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.stereotype.Component;

import java.util.HashMap;
import java.util.Map;

@Aspect
@Component
public class MethodTimerService {
    Logger logger = LoggerFactory.getLogger(MethodTimerService.class);
    static Map<String, Long> loggedMethods = new HashMap<>();
    String signature = null;

    @Around("@annotation(com.lixar.apba.aop.annotations.MethodTimer)")
    public Object methodTimer(ProceedingJoinPoint proceedingJoinPoint) throws Throwable {
        long startTime = System.currentTimeMillis();
        Object callback = proceedingJoinPoint.proceed();
        long endTime = System.currentTimeMillis();
        insertLoggedExecution(proceedingJoinPoint, startTime, endTime);
        return callback;
    }

    private void insertLoggedExecution(ProceedingJoinPoint pjp, long startTime, long endTime) {
        signature = String.valueOf(pjp.getSignature());
        long calculatedTime = getCalculatedTime(startTime, endTime);
        loggedMethods.put(String.valueOf(pjp.getSignature()), calculatedTime);
        System.out.println("Method name: " + signature + " : TotalExecutionTime: " + calculatedTime);
    }

    private long getCalculatedTime(long startTime, long endTime) {
        long calculatedTime = endTime - startTime;
        if(loggedMethods.containsKey(signature)) {
            calculatedTime = endTime - startTime + loggedMethods.get(signature);
        }
        return calculatedTime;
    }

    public static void outPutLoggedExecution() {
        for(var log : loggedMethods.entrySet()) {
            System.out.println("Method name: " + log.getKey() + " : TotalExecutionTime: " + log.getValue());
        }
    }
}

The annotation is never being called, how can I fix this?

Answer 1

Configuration
First of all, you need to configure your IDE to work with AspectJ.
1. Configuration for IntelliJ

• install AspectJ plugin
• configure compiller

2. Configuration for Eclipse

3. Spring configuration documentation

4. Spring Boot configuration

Code changes

1. Using @Pointcut

Declare @Pointcut for your custom @MethodTimer annotation

    @Pointcut("@annotation(methodTimer)")
    public void callMethod(MethodTimer methodTimer) { }

Pointcut: A predicate that matches join points. Advice is associated with a pointcut expression and runs at any join point matched by the pointcut (for example, the execution of a method with a certain name). The concept of join points as matched by pointcut expressions is central to AOP: Spring uses the AspectJ pointcut language by default.

Bind Pointcut with your @Around advice. Also, you need to restrict @Around advice only for execution, otherwise method will be called twice: Why does AspectJ @Around advice execute twice?

    @Around("callMethod(methodTimer) && execution(* *(..))")
    public Object methodTimer(ProceedingJoinPoint proceedingJoinPoint, MethodTimer methodTimer) throws Throwable {
        long startTime = System.currentTimeMillis();
        Object callback = proceedingJoinPoint.proceed();
        long endTime = System.currentTimeMillis();
        insertLoggedExecution(proceedingJoinPoint, startTime, endTime);
        return callback;
    }

2. Another variant, custom annotation binding

    @Around("@annotation(methodTimer) && execution(* *(..)) ")
    public Object methodTimer(ProceedingJoinPoint proceedingJoinPoint, MethodTimer methodTimer) throws Throwable {
        long startTime = System.currentTimeMillis();
        Object callback = proceedingJoinPoint.proceed();
        long endTime = System.currentTimeMillis();
        insertLoggedExecution(proceedingJoinPoint, startTime, endTime);
        return callback;
    }

Full code:

public static void main(String[] args) {
    Simpleton simp = new Simpleton();
    simp.howLongDidThisTake();
}

public class Simpleton {
    @MethodTimer
    public void howLongDidThisTake() {
        try {
            Thread.sleep(50);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
}

@Target(ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
public @interface MethodTimer{
}

@Aspect
@Component
public class MethodTimerService {
    static Map<String, Long> loggedMethods = new HashMap<>();
    String signature = null;

    @Pointcut("@annotation(methodTimer)")
    public void callMethod(MethodTimer methodTimer) { }

    @Around("callMethod(methodTimer) && execution(* *(..)) ")
    public Object methodTimer(ProceedingJoinPoint proceedingJoinPoint, MethodTimer methodTimer) throws Throwable {
        long startTime = System.currentTimeMillis();
        Object callback = proceedingJoinPoint.proceed();
        long endTime = System.currentTimeMillis();
        insertLoggedExecution(proceedingJoinPoint, startTime, endTime);
        return callback;
    }

    private void insertLoggedExecution(ProceedingJoinPoint pjp, long startTime, long endTime) {
        signature = String.valueOf(pjp.getSignature());
        long calculatedTime = getCalculatedTime(startTime, endTime);
        loggedMethods.put(String.valueOf(pjp.getSignature()), calculatedTime);
        System.out.println("Method name: " + signature + " : TotalExecutionTime: " + calculatedTime);
    }

    private long getCalculatedTime(long startTime, long endTime) {
        long calculatedTime = endTime - startTime;
        if(loggedMethods.containsKey(signature)) {
            calculatedTime = endTime - startTime + loggedMethods.get(signature);
        }
        return calculatedTime;
    }

    public static void outPutLoggedExecution() {
        for(Map.Entry<String, Long> log : loggedMethods.entrySet()) {
            System.out.println("Method name: " + log.getKey() + " : TotalExecutionTime: " + log.getValue());
        }
    }
}

Program execution result

Method name: void Simpleton.howLongDidThisTake() : TotalExecutionTime: 55