将Spring @Retryable与Jackson json反序列化一起使用

Question

I'm trying to use Spring Retry for Jackson deserialization into a POJO object like so:

@Data
public class myPOJO {
    private String cmpStr = "test";
    private String myStr;

    @Retryable(maxAttempts=3, value=RuntimeException.class, backoff=@Backoff(delay=3000))
    @JsonProperty("jsonElement")
    private void retryableFunc(Map<String, Object> jsonElement) {
        try {
            myStr = jsonElement.get("jsonAttribute");
            if (!Objects.equals(myStr, cmpStr))
                throw new RuntimeException("Bad Response");
        }
        catch (Exception e) {
            throw new RuntimeException("Bad Response");
        }
    }

    @Recover
    private void recover(Exception e) {
        System.out.println("Recover triggered");
    }
}

MyPOJO is instantiated like this:

RestTemplate restTemplate = new RestTemplate();
HttpHeaders headers = new HttpHeaders();
headers.setAccept(Collections.singleTonList(MediaType.APPLICATION_JSON));
String jsonAttribute = restTemplate.exchange(URL, HttpMethod.GET, new HttpEntity<>(headers), myPOJO.class).getBody().getMyStr();

Main app looks like:

@SpringBootApplication
@EnableRetry
public class mainApplication {
    public static void main(String[] args) {
        SpringApplication.run(mainApplication.class, args);
    }
}

JSON response looks like this:

{
    "jsonElement": {
        "jsonAttribute": "test1"
    }
}

Retry is never triggered, but the exception is thrown:

Error while extracting response for type myPOJO and content type [application/json;charset=utf-8]; nested exception is org.springframework.http.converter.HttpMessageNotReadableException: JSON parse error: Bad Response; nested exception is com.fasterxml.jackson.databind.JsonMappingException: Bad Response

Answer 1

I think you have some basic misunderstanding. Spring Retry can only be applied to beans that Spring manages. Your POJO might be created by a Spring component ( RestTemplate ), it's not a managed @Bean in the application context.

You can't use annotation-based retry on objects that are not managed by the application context.

You still didn't show how you are calling the retryableFunc but you should, instead, call your object from some helper bean:

public class MyHelper {

    @Retryable(...)
    public void validateMyPojo(MyPojo pojo, Map<...,...> jsonElement) {
        pojo.retryableFunc(jsonElement);
    }

}

and

@Bean
public MyHelper myHelper() {
    return new MyHelper();
}

Or, you can simply use a RetryTemplate to call the method.