[FIXED] Kotlin: RestTemplateCustomizer customize() method is not being called

Issue

• I am writing a customize ResponseErrorHandler for all RestTemplate api call in application. This application is a Spring Boot application and written in Kotlin

My code:

ServiceApiErrorHandler.class

class ServiceApiErrorHandler(
    @Autowired
    val agentAuthService: AgentAuthService
) : DefaultResponseErrorHandler() {
    companion object {
        private val logger: LogService = LogServiceImpl(ServiceApiErrorHandler::class.java)
    }

    override fun hasError(response: ClientHttpResponse): Boolean {
        return (response.statusCode.is4xxClientError || response.statusCode.is5xxServerError)
    }

    override fun handleError(response: ClientHttpResponse) {
        logger.info("LOGIN AGAIN 1")

    }

    override fun handleError(url: URI, method: HttpMethod, response: ClientHttpResponse) {
        if (response.statusCode == HttpStatus.UNAUTHORIZED && ServiceApiEnpoint.isServiceApiEndpoint(url = url.toString())) {
            logger.info("LOGIN AGAIN")
            agentAuthService.callLogin();
        }
    }
}

CustomRestTemplateCustomizer class

class CustomRestTemplateCustomizer(
    @Autowired
    val agentAuthService: AgentAuthService
) : RestTemplateCustomizer {
    override fun customize(restTemplate: RestTemplate) {
            restTemplate.errorHandler = ServiceApiErrorHandler(agentAuthService = agentAuthService)
    }
}

ClientHttpConfig class

@Configuration
class ClientHttpConfig(
    @Autowired
    val agentAuthService: AgentAuthService
) {
    @Bean
    fun customRestTemplateCustomizer(): CustomRestTemplateCustomizer {
        return CustomRestTemplateCustomizer(agentAuthService = agentAuthService);
    }
}

The problem is when I run, RestTemplate still handle error using DefaultResponseErrorHandler and after debug, I quickly realize that the customize() method in class CustomRestTemplateCustomizer was never being called.

So my questions is:

• Is customize() method suppose to be automatic called? If not, how should i call it?
• Does my code is ok to implement customize ResponseErrorHandler?

Note: I follow the tutorial in Java: https://www.baeldung.com/spring-rest-template-builder to write this version in Kotlin.

Solution

how do you create the RestTemplate instance?

try adding a Bean, then the customizer should be used

@Configuration
class ClientHttpConfig(
    @Autowired
    val agentAuthService: AgentAuthService,
    @Autowired val builder: RestTemplateBuilder
) {
    @Bean
    fun customRestTemplateCustomizer(): CustomRestTemplateCustomizer {
        return CustomRestTemplateCustomizer(agentAuthService = agentAuthService);
    }

    @Bean
    fun customizedRestTemplate(): RestTemplate {
        return builder.build();
    }
}

Edit: needs to be created by RestTemplateBuilder

Answered By - Marc Stroebel
Answer Checked By - Marie Seifert (JavaFixing Admin)