Response received from service to controller class is null after aspect gets executed on service class method

Question

I have a controller class which further calls service class method. An AOP @Around aspect is applied on the service class method.

package com.hetal.example;

@RestController
public class CustomerController {
    @Autowired
    CustomerService customerService;

    @RequestMapping(value = "/getDetails", method = RequestMethod.GET)
    public String getCustomerDetails() {
        System.out.println("Inside controller class");
        String details = customerService.getDetails(custName);
        System.out.println("Customer details is = " + details); // prints null
    }
}

package com.hetal.example;

@Service
public class CustomerServiceImpl implements CustomerService {
    @Override
    public String getDetails(String custName) {
        //some code
        returns "Customer details";
    }
}

An aspect is written to be executed @Around the method getDetails() of CustomerServiceImpl

package com.hetal.config;

public class JoinPointConfig {
   @Pointcut(value="execution(* com.hetal.example.CustomerService.getDetails(..) && args(custName)")) 
   public void handleCustomerDetails(String custName) {}
}

package com.hetal.config;

@Aspect
@Component
public class CustomerAspect {
   @Around("com.hetal.config.JoinPointConfig.handleCustomerDetails(custName)") 
   public Object aroundCustomerAdvice(ProceedingJoinPoint joinpoint, String custName) {
       System.out.println("Start aspect");
       Object result= null;
       try { 
          result = joinpoint.proceed();
          System.out.println("End aspect");
       }
       catch(Exception e) {}
    return result;
   }
}

Execution goes as below,

1. Controller calls CustomerServiceImpl.getDetails method.

2. CustomerAspect is called, prints "Start aspect". //before advice

3. joinpoint.proceed() calls actual CustomerServiceImpl.getDetails method.

4. CustomerServiceImpl.getDetails returns a string "Customer details" and control comes back to the aspect, prints "End aspect" //after returning advice

5. Control goes back to controller class but the response received is null.

I want the response returned from the service class into the controller class after the completion of the aspect.

Thank you in advance !!

Answer 1

Yeah you some compilation issue in your applications make those changes and with the belwo return type issue in Aspect class, but the main issue is with your Aspect class, its void return type hence that coming as null you should return the result as object , below is the code

package com.hetal.config;
    @Aspect
    @Component
    public class CustomerAspect {

       @Around("com.hetal.config.JoinPointConfig.handleCustomerDetails(custName)") 
       public Object aroundCustomerAdvice(ProceedingJoinPoint joinpoint, String custName) {
           System.out.println("Start aspect");

           Object result= null;
           try { 
              result = joinpoint.proceed();
              System.out.println("End aspect");
           }
           catch(Exception e) {}
 return result;
       }
    }