Master Advanced Spring Boot: Date Params, Conditional Controllers & Async Timeouts

1. Elegant Date Parameter Handling

Spring MVC automatically converts many data types, including Java 8 date types. Example:

<code>@GetMapping("/date")
public Object date(@RequestParam(value = "start")
    @DateTimeFormat(pattern = "yyyy-MM-dd HH:mm:ss")
    LocalDateTime start) {
    return start;
}</code>

Request example:

If repeatedly adding the annotation feels cumbersome, you can register a custom converter.

<code>public class LocalDateTimeConverter implements Converter<String, LocalDateTime> {
    private final DateTimeFormatter formatter;
    public LocalDateTimeConverter(String pattern) {
        this.formatter = DateTimeFormatter.ofPattern(pattern);
    }
    public LocalDateTime convert(String source) {
        if (source == null || source.isEmpty()) {
            return null;
        }
        return LocalDateTime.parse(source, formatter);
    }
}</code>

Register the converter in the container:

<code>@Component
public class DateConfigure implements WebMvcConfigurer {
    @Override
    public void addFormatters(FormatterRegistry registry) {
        registry.addConverter(new LocalDateTimeConverter("yyyy-MM-dd HH:mm:ss"));
    }
}</code>

2. Programmatic Control of Controller Activation

You can enable a controller only when a specific property is true using Spring’s conditional annotations:

<code>@ConditionalOnExpression("#{${pack.controller.user.enabled} == true}")
@RestController
@RequestMapping("/users")
public class UserController {}
</code>

When pack.controller.user.enabled=true in the environment, UserController becomes active.

Alternatively, use an interceptor to reject requests:

<code>public class ConditionalRejectionInterceptor implements HandlerInterceptor {
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        String requestUri = request.getRequestURI();
        if (shouldReject(requestUri)) {
            response.setStatus(HttpStatus.NOT_FOUND.value());
            return false;
        }
        return true;
    }
    private boolean shouldReject(String requestUri) {
        return requestUri.startsWith("/users");
    }
}
</code>

3. Unified API Prefix for Controllers

Goal: prepend /api to all controller paths, e.g., /api/customer , /api/orders .

Method 1: YAML configuration

<code>spring:
  mvc:
    servlet:
      path: /api
# or
server:
  servlet:
    context-path: /api
</code>

Method 2: Java configuration

<code>@Configuration
public class PrefixConfig implements WebMvcConfigurer {
    @Override
    public void configurePathMatch(PathMatchConfigurer configurer) {
        configurer.addPathPrefix("/api", HandlerTypePredicate.forAnnotation(RestController.class));
    }
}
</code>

4. Service‑Layer Parameter Validation with Annotations

Validation can also be performed in the service layer by injecting Validator :

<code>private final Validator validator;
public ValidationService(Validator validator) {
    this.validator = validator;
}
public User save(User user) {
    Set<ConstraintViolation<User>> validate = this.validator.validate(user);
    System.err.println(validate);
    return user;
}
</code>

Example output shows violations such as “姓名必须填写” (name required) and “年龄不能小于1” (age must be greater than 0). You can also place @Validated on the class and handle violations globally.

5. Controlling Asynchronous Endpoint Timeouts

Common async return types are @Async with CompletableFuture , Callable , or DeferredResult . Example using Callable :

<code>@GetMapping("")
public Callable<String> index() throws InterruptedException {
    return new Callable<String>() {
        @Override
        public String call() throws Exception {
            // Simulate delay
            Thread.sleep(5000);
            return "Pack Async Task";
        }
    };
}
</code>

Configure timeout via YAML:

<code>spring:
  mvc:
    async:
      request-timeout: 3000
</code>

Or programmatically:

<code>@Component
public class TimeoutConfig implements WebMvcConfigurer {
    @Override
    public void configureAsyncSupport(AsyncSupportConfigurer configurer) {
        configurer.setDefaultTimeout(1000);
    }
}
</code>

Register a timeout interceptor to return a default response when a timeout occurs:

<code>@Bean
TimeoutCallableProcessingInterceptor timeoutInterceptor() {
    return new TimeoutCallableProcessingInterceptor() {
        @Override
        public <T> Object handleTimeout(NativeWebRequest request, Callable<T> task) throws Exception {
            return "超时";
        }
    };
}
</code>