Jackson未抛出自定义异常求助：日期反序列化异常未被正确捕获

相关代码 #

实体类字段定义 #

@NotNull
@JsonDeserialize(using = LocalDateDeserializer.class)
@Schema(description = "BIRTH DATE", example = "1992-02-15")
private LocalDate birthDate;

自定义Jackson反序列化器 #

public class LocalDateDeserializer extends StdDeserializer<LocalDate> {

    private static final DateTimeFormatter DATE_TIME_FORMATTER = DateTimeFormatter.ofPattern("yyyy-MM-dd");

    protected LocalDateDeserializer() {
        super(LocalDate.class);
    }

    @Override
    public LocalDate deserialize(
            final JsonParser jsonParser,
            final DeserializationContext deserializationContext)
            throws IOException {
        JsonNode node = jsonParser.getCodec().readTree(jsonParser);
        String date = node.asText();

        try {
            return LocalDate.parse(date, DATE_TIME_FORMATTER);
        } catch (Exception e) {
            throw new InvalidDateFormatException("Invalid format" + date);
        }
    }
}

自定义异常类 #

public class InvalidDateFormatException extends RuntimeException {
    public InvalidDateFormatException(final String message) {
        super(message);
    }
}

全局异常处理器 #

@ControllerAdvice
public class ApplicationExceptionHandler extends ResponseEntityExceptionHandler {

    public static final String MISSING_HEADER_MESSAGE = "{0} header must be informed";

    @ExceptionHandler(InvalidDateFormatException.class)
    public ResponseEntity<String> handleInvalidDateFormatException(InvalidDateFormatException ex) {
        return new ResponseEntity<>(ex.getMessage(), HttpStatus.BAD_REQUEST);
    }
}

问题现象 #

发送格式错误的birthDate请求时，代码进入反序列化器并捕获到异常，但自定义错误未生效，仅返回通用400错误。

核心原因：Jackson反序列化阶段抛出的自定义异常会被Spring的HttpMessageConverter包装成HttpMessageNotReadableException，而继承ResponseEntityExceptionHandler的全局处理器默认会处理这个包装后的异常，导致自定义异常的处理器无法触发。

方式一：修改反序列化器，使用Jackson内置异常处理机制 #

调整反序列化器的异常抛出逻辑，利用Jackson的DeserializationContext抛出规范异常，让Spring能正确识别错误信息：

@Override
public LocalDate deserialize(
        final JsonParser jsonParser,
        final DeserializationContext deserializationContext)
        throws IOException {
    JsonNode node = jsonParser.getCodec().readTree(jsonParser);
    String date = node.asText();

    try {
        return LocalDate.parse(date, DATE_TIME_FORMATTER);
    } catch (Exception e) {
        // 用Jackson的方法抛出格式错误异常
        return deserializationContext.handleWeirdStringValue(LocalDate.class, date,
                "Invalid format: " + date);
    }
}

然后在全局处理器中重写handleHttpMessageNotReadable方法，返回自定义响应：

@Override
protected ResponseEntity<Object> handleHttpMessageNotReadable(HttpMessageNotReadableException ex,
                                                              HttpHeaders headers,
                                                              HttpStatus status,
                                                              WebRequest request) {
    Throwable cause = ex.getCause();
    if (cause instanceof JsonMappingException) {
        // 提取Jackson抛出的错误信息返回
        return new ResponseEntity<>(cause.getMessage(), HttpStatus.BAD_REQUEST);
    }
    // 其他情况沿用默认处理
    return super.handleHttpMessageNotReadable(ex, headers, status, request);
}

方式二：在全局处理器中处理包装后的异常 #

无需修改反序列化器，直接在全局处理器中新增对HttpMessageNotReadableException的处理，提取根异常判断是否为自定义异常：

@ExceptionHandler(HttpMessageNotReadableException.class)
public ResponseEntity<String> handleHttpMessageNotReadable(HttpMessageNotReadableException ex) {
    Throwable rootCause = ex.getRootCause();
    if (rootCause instanceof InvalidDateFormatException) {
        return new ResponseEntity<>(rootCause.getMessage(), HttpStatus.BAD_REQUEST);
    }
    return new ResponseEntity<>("Invalid request body", HttpStatus.BAD_REQUEST);
}

内容的提问来源于stack exchange，提问作者Jossany Moura