对于每个空响应返回404

Question

我想在spring boot中，当响应对象对于每个响应自动为null时返回404。

我需要建议。

我不想检查控制器中的对象是否为null。

Answer 1

与@manish的答案类似(https://stackoverflow.com/a/43891952/986160)但是没有AspectJ切入点，而是使用另一个@ControllerAdvice：

步骤1:NotFoundException类：

public class NotFoundException extends RuntimeException {
    public NotFoundException(String msg) {
        super(msg);
    }
    public NotFoundException() {}
}

步骤2：检查endpoint中返回的主体是否为null，并抛出NotFoundException:

@ControllerAdvice
public class NotFoundAdvice implements ResponseBodyAdvice {
    @Override
    public boolean supports(MethodParameter returnType, Class converterType) {
        return true;
    }

    @Override
    @SuppressWarnings("unchecked")
    public Object beforeBodyWrite(Object body, MethodParameter returnType, MediaType selectedContentType, Class selectedConverterType, ServerHttpRequest request, ServerHttpResponse response) {
        if (body == null) {
            throw new NotFoundException("resource not found");
        }
        return body;
    }
}

步骤3：处理NotFoundExcture并使响应具有404的状态

@ControllerAdvice
public class GlobalExceptionAdvice {

    @Data
    public class ErrorDetails {
        private Date timestamp;
        private String message;
        private String details;

        public ErrorDetails(Date timestamp, String message, String details) {
            super();
            this.timestamp = timestamp;
            this.message = message;
            this.details = details;
        }
    }

    @ExceptionHandler(NotFoundException.class)
    public final ResponseEntity<ErrorDetails> notFoundHandler(Exception ex, WebRequest request) {
        ErrorDetails errorDetails = new ErrorDetails(new Date(), ex.getMessage(),
                request.getDescription(false));
        return new ResponseEntity<>(errorDetails, HttpStatus.NOT_FOUND);
    }
}

步骤3的备选方案：

您可以只注释您的NotFoundExc0019与@响应状态和覆盖fillInStackTrace（）（从https://stackoverflow.com/a/31263942/986160），使其具有类似的效果，以GlobalExceptionAdwn，并且不会显示这样的stackTrace：

@ResponseStatus(value = HttpStatus.NOT_FOUND,reason =  "resource not found")
public class NotFoundException extends RuntimeException {
    public NotFoundException(String msg) {
        super(msg);
    }
    public NotFoundException() {}

    @Override
    public synchronized Throwable fillInStackTrace() {
        return this;
    }
}

Answer 2

在Spring中实现这一点的最简单方法是编写自己的异常类，如下所示

@ResponseStatus(value = HttpStatus.NOT_FOUND)
class ResourceNotFoundException extends RuntimeException{
}

然后从任意位置抛出ResourceNotFoundException。

if (something == null) throw new ResourceNotFoundException();

更多-

Answer 3

您需要多个Spring模块来完成此操作。基本步骤是：

1. 声明一个异常类，该类可用于在存储库方法未返回预期值时引发异常

步骤1：异常类

public class ResourceNotFoundException extends RuntimeException {}

步骤2：控制器建议

@ControllerAdvice
public class ResourceNotFoundExceptionHandler
{
  @ExceptionHandler(ResourceNotFoundException.class)
  @ResponseStatus(HttpStatus.NOT_FOUND)
  public void handleResourceNotFound() {}
}

第3步：建议

@Aspect
@Component
public class InvalidRepositoryReturnValueAspect
{
  @AfterReturning(pointcut = "execution(* org.example.data.*Repository+.findOne(..))", returning = "result")
  public void intercept(final Object result)
  {
    if (result == null)
    {
      throw new ResourceNotFoundException();
    }
  }
}

Github上提供了一个示例应用程序来演示所有这些功能。使用REST客户端（如Postman for Google Chrome）添加一些记录。然后，尝试通过标识符获取现有记录将正确返回记录，但尝试通过不存在的标识符获取记录将返回404。