In this spring aop example, we will learn to use aspectj @Around annotation. @Around annotated methods run before and after the all methods matching with pointcut expression.
In this example, We will create simple spring application, add logging around aspect and then invoke aspect methods based on pointcuts information passed in @Around annotation.
1. AspectJ @Around annotation usage
@Around advice surrounds a joinpoint such as a method invocation. This is the most powerful kind of advice. Around advice can perform custom behavior before and after the method invocation. It is also responsible for choosing whether to proceed to the join point or to shortcut the advised method execution by returning its own return value or throwing an exception.
@Aspect
public class LoggingAspect {
@Around("execution(* com.howtodoinjava.app.service.impl.EmployeeManagerImpl.*(..))")
public void logAroundAllMethods(ProceedingJoinPoint joinPoint) { ... }
@Around("execution(* com.howtodoinjava.app.service.impl.EmployeeManagerImpl.getEmployeeById(..))")
public void logAroundGetEmployee(ProceedingJoinPoint joinPoint) { ... }
}
Do not forget to use
ProceedingJoinPoint as parameter. You must call ProceedingJoinPoint.proceed(); method, else the original method will be executed.2. Project Structure
3. Spring AOP AspectJ maven dependencies
I have added spring core, spring aop and aspectj dependencies.
<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 http://maven.apache.org/xsd/maven-4.0.0.xsd;
<modelVersion>4.0.0</modelVersion>
<groupId>com.howtodoinjava</groupId>
<artifactId>SpringAOPExamples</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>Spring AOP Examples</name>
<dependencies>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context</artifactId>
<version>4.3.2.RELEASE</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context-support</artifactId>
<version>4.3.2.RELEASE</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-aop</artifactId>
<version>4.3.2.RELEASE</version>
</dependency>
<dependency>
<groupId>org.aspectj</groupId>
<artifactId>aspectjrt</artifactId>
<version>1.8.9</version>
</dependency>
<dependency>
<groupId>org.aspectj</groupId>
<artifactId>aspectjweaver</artifactId>
<version>1.8.9</version>
</dependency>
</dependencies>
</project>4. Enable Spring AOP AspectJ Support
In XML config file, you can add aop:aspectj-autoproxy element to enable @AspectJ annotation support.
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:aop="http://www.springframework.org/schema/aop"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
http://www.springframework.org/schema/aop/
http://www.springframework.org/schema/aop/spring-aop-3.0.xsd ">
<!-- Enable @AspectJ annotation support -->
<aop:aspectj-autoproxy />
<!-- Employee manager -->
<bean id="employeeManager" class="com.howtodoinjava.app.service.impl.EmployeeManagerImpl" />
<!-- Logging Aspect -->
<bean id="loggingAspect" class="com.howtodoinjava.app.aspect.LoggingAspect" />
</beans>
5. Methods around which aspects needs to be executed
EmployeeManager.java and EmployeeManagerImpl.java
public interface EmployeeManager
{
public EmployeeDTO getEmployeeById(Integer employeeId);
public List<EmployeeDTO> getAllEmployee();
public void createEmployee(EmployeeDTO employee);
public void deleteEmployee(Integer employeeId);
public void updateEmployee(EmployeeDTO employee);
}
public class EmployeeManagerImpl implements EmployeeManager
{
public EmployeeDTO getEmployeeById(Integer employeeId)
{
System.out.println("Method getEmployeeById() called");
return new EmployeeDTO();
}
public List<EmployeeDTO> getAllEmployee()
{
System.out.println("Method getAllEmployee() called");
return new ArrayList<EmployeeDTO>();
}
public void createEmployee(EmployeeDTO employee)
{
System.out.println("Method createEmployee() called");
}
public void deleteEmployee(Integer employeeId)
{
System.out.println("Method deleteEmployee() called");
}
public void updateEmployee(EmployeeDTO employee)
{
System.out.println("Method updateEmployee() called");
}
}
6. Write AspectJ Annotated Class and Methods
Write aspectj annotated class and methods with pointcut information.
@Aspect
public class LoggingAspect {
@Around("execution(* com.howtodoinjava.app.service.impl.EmployeeManagerImpl.*(..))")
public void logAroundAllMethods(ProceedingJoinPoint joinPoint) throws Throwable
{
System.out.println("****LoggingAspect.logAroundAllMethods() : " + joinPoint.getSignature().getName() + ": Before Method Execution");
try {
joinPoint.proceed();
} finally {
//Do Something useful, If you have
}
System.out.println("****LoggingAspect.logAroundAllMethods() : " + joinPoint.getSignature().getName() + ": After Method Execution");
}
@Around("execution(* com.howtodoinjava.app.service.impl.EmployeeManagerImpl.getEmployeeById(..))")
public void logAroundGetEmployee(ProceedingJoinPoint joinPoint) throws Throwable
{
System.out.println("****LoggingAspect.logAroundGetEmployee() : " + joinPoint.getSignature().getName() + ": Before Method Execution");
try {
joinPoint.proceed();
} finally {
//Do Something useful, If you have
}
System.out.println("****LoggingAspect.logAroundGetEmployee() : " + joinPoint.getSignature().getName() + ": After Method Execution");
}
@Around("execution(* com.howtodoinjava.app.service.impl.EmployeeManagerImpl.createEmployee(..))")
public void logAroundCreateEmployee(ProceedingJoinPoint joinPoint) throws Throwable
{
System.out.println("****LoggingAspect.logAroundCreateEmployee() : " + joinPoint.getSignature().getName() + ": Before Method Execution");
try {
joinPoint.proceed();
} finally {
//Do Something useful, If you have
}
System.out.println("****LoggingAspect.logAroundCreateEmployee() : " + joinPoint.getSignature().getName() + ": After Method Execution");
}
}
7. Spring AspectJ @Around example
Now let’s test whether above configured aspects execute on given pointcut information.
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import com.howtodoinjava.app.model.EmployeeDTO;
import com.howtodoinjava.app.service.EmployeeManager;
public class TestMain
{
@SuppressWarnings("resource")
public static void main(String[] args) {
ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");
EmployeeManager manager = (EmployeeManager) context.getBean("employeeManager");
manager.getEmployeeById(1);
manager.createEmployee(new EmployeeDTO());
}
}
****LoggingAspect.logAroundAllMethods() : getEmployeeById: Before Method Execution ****LoggingAspect.logAroundGetEmployee() : getEmployeeById: Before Method Execution Method getEmployeeById() called ****LoggingAspect.logAroundGetEmployee() : getEmployeeById: After Method Execution ****LoggingAspect.logAroundAllMethods() : getEmployeeById: After Method Execution ****LoggingAspect.logAroundAllMethods() : createEmployee: Before Method Execution ****LoggingAspect.logAroundCreateEmployee() : createEmployee: Before Method Execution Method createEmployee() called ****LoggingAspect.logAroundCreateEmployee() : createEmployee: After Method Execution ****LoggingAspect.logAroundAllMethods() : createEmployee: After Method Execution
Clearly aspect advices executed around relevant jointpoints.
Happy Learning !!
References:
Spring AOP Reference
@Around Annotation
@Aspect Annotation
AspectJ Annotation Config Example
Different Pointcut Expressions With Examples
Srinivasa Rao Gurram
In my current scenario, I need to provide mock response for specific methods. The above article helped me to understand the concept.
@Around("execution(* eu.dreamix.rest.SoundController.callSound(..))") public Object mockSound(ProceedingJoinPoint jp) throws Throwable { if (isMockEnabled) { System.out.println("In mockSound" + customer); /*Customer customer = new Customer(); customer.setName("SriMock");*/ return ResponseEntity.ok(customer); } else { return jp.proceed(); } }