BAEL-7413 - Logging With AOP in Spring (#15810)

* BAEL-7413 - Logging With AOP in Spring

* Add GreetingServiceWithoutAOP class

spring-aop-2/src/main/java/com/baeldung/logging/GreetingService.java

@@ -0,0 +1,11 @@
+package com.baeldung.logging;
+
+import org.springframework.stereotype.Service;
+
+@Service
+public class GreetingService {
+
+    public String greet(String name) {
+        return String.format("Hello %s", name);
+    }
+}

spring-aop-2/src/main/java/com/baeldung/logging/GreetingServiceWithoutAOP.java

@@ -0,0 +1,18 @@
+package com.baeldung.logging;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.stereotype.Service;
+
+@Service
+public class GreetingServiceWithoutAOP {
+
+    private static final Logger logger = LoggerFactory.getLogger(GreetingServiceWithoutAOP.class);
+
+    public String greet(String name) {
+        logger.info(">> greet() - {}", name);
+        String result = String.format("Hello %s", name);
+        logger.info("<< greet() - {}", result);
+        return result;
+    }
+}

spring-aop-2/src/main/java/com/baeldung/logging/LoggingAspect.java

@@ -0,0 +1,55 @@
+package com.baeldung.logging;
+
+import org.aspectj.lang.JoinPoint;
+import org.aspectj.lang.ProceedingJoinPoint;
+import org.aspectj.lang.annotation.AfterReturning;
+import org.aspectj.lang.annotation.AfterThrowing;
+import org.aspectj.lang.annotation.Around;
+import org.aspectj.lang.annotation.Aspect;
+import org.aspectj.lang.annotation.Before;
+import org.aspectj.lang.annotation.Pointcut;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.stereotype.Component;
+
+import java.util.Arrays;
+
+@Aspect
+@Component
+public class LoggingAspect {
+
+    private static final Logger logger = LoggerFactory.getLogger(LoggingAspect.class);
+
+    @Pointcut("execution(public * com.baeldung.logging.*.*(..))")
+    private void publicMethodsFromLoggingPackage() {
+    }
+
+    @Before(value = "publicMethodsFromLoggingPackage()")
+    public void logBefore(JoinPoint joinPoint) {
+        Object[] args = joinPoint.getArgs();
+        String methodName = joinPoint.getSignature().getName();
+        logger.info(">> {}() - {}", methodName, Arrays.toString(args));
+    }
+
+    @AfterReturning(value = "publicMethodsFromLoggingPackage()", returning = "result")
+    public void logAfter(JoinPoint joinPoint, Object result) {
+        String methodName = joinPoint.getSignature().getName();
+        logger.info("<< {}() - {}", methodName, result);
+    }
+
+    @AfterThrowing(pointcut = "publicMethodsFromLoggingPackage()", throwing = "exception")
+    public void logException(JoinPoint joinPoint, Throwable exception) {
+        String methodName = joinPoint.getSignature().getName();
+        logger.error("<< {}() - {}", methodName, exception.getMessage());
+    }
+
+    @Around(value = "publicMethodsFromLoggingPackage()")
+    public Object logAround(ProceedingJoinPoint joinPoint) throws Throwable {
+        Object[] args = joinPoint.getArgs();
+        String methodName = joinPoint.getSignature().getName();
+        logger.info(">> {}() - {}", methodName, Arrays.toString(args));
+        Object result = joinPoint.proceed();
+        logger.info("<< {}() - {}", methodName, result);
+        return result;
+    }
+}

spring-aop-2/src/test/java/com/baeldung/logging/GreetingServiceUnitTest.java

@@ -0,0 +1,23 @@
+package com.baeldung.logging;
+
+import com.baeldung.Application;
+import org.junit.jupiter.api.Test;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.context.SpringBootTest;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+
+@SpringBootTest(classes = Application.class)
+class GreetingServiceUnitTest {
+
+    @Autowired
+    private GreetingService greetingService;
+
+    @Test
+    void givenName_whenGreet_thenReturnCorrectResult() {
+        String result = greetingService.greet("Baeldung");
+        assertNotNull(result);
+        assertEquals("Hello Baeldung", result);
+    }
+}