Spring Web 应用中自定义校验异常的统一处理：从 500 到 400

@Documented
@Retention(RetentionPolicy.RUNTIME)
@Target({ METHOD, FIELD, CONSTRUCTOR, PARAMETER, TYPE_USE })
@Constraint(validatedBy = ListValidator.class)
public @interface ValidList  {
    String message() default "List cannot empty or contain null values";
    Class<?>[] groups() default {};
    Class<? extends Payload>[] payload() default {};
}

import javax.validation.ConstraintValidator;
import javax.validation.ConstraintValidatorContext;
import java.util.List;
import java.util.Objects;

public class ListValidator implements ConstraintValidator<ValidList, List<? extends Object>> {
    @Override
    public boolean isValid(List<? extends Object> list,
                           ConstraintValidatorContext context) {
        // 如果列表为 null、为空或包含任何 null 元素，则标记为无效
        return !(list == null || list.isEmpty() || list.stream().anyMatch(Objects::isNull));
    }

    @Override
    public void initialize(ValidList constraintAnnotation) {}
}

import org.springframework.http.MediaType;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RestController;

import javax.validation.Valid;
import javax.validation.constraints.NotNull;
import java.util.ArrayList;

@RestController
public class RequestAPI {
    @PostMapping(value = "/request",
        consumes = MediaType.APPLICATION_JSON_VALUE,
        produces = MediaType.APPLICATION_JSON_VALUE)
    public ResponseEntity request(
        @Valid @NotNull @RequestBody(required = false) Data data) {
        // 业务逻辑处理
        return ResponseEntity.ok("Request processed successfully");
    }
}

// 应用了自定义校验注解的 Data 类
@ValidList
public class Data extends ArrayList<@Valid Entries> { }

// 列表元素类
public class Entries {
  @NotNull
  String firstName;

  @NotNull
  String lastName;
}

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.bind.annotation.RestControllerAdvice;
import org.springframework.web.servlet.mvc.method.annotation.ResponseEntityExceptionHandler;

import javax.validation.ConstraintViolationException; // 确保导入正确的包
import java.util.stream.Collectors; // 用于处理详细错误信息

@RestControllerAdvice
public class ApiExceptionHandler extends ResponseEntityExceptionHandler {

    private static final Logger logger = LoggerFactory.getLogger(ApiExceptionHandler.class);

    /**
     * 处理 ConstraintViolationException 异常，通常由方法参数校验失败引起
     * 或通过 Validator 接口手动校验时抛出。
     * 返回 400 Bad Request。
     */
    @ExceptionHandler(value = {ConstraintViolationException.class})
    public ResponseEntity<Object> handleConstraintViolationException(ConstraintViolationException ex) {
        logger.error("Constraint Violation Exception: {}", ex.getMessage(), ex);

        // 提取详细的校验错误信息
        String errorMessage = ex.getConstraintViolations().stream()
                .map(violation -> violation.getPropertyPath() + ": " + violation.getMessage())
                .collect(Collectors.joining(", "));

        // 构建自定义的错误响应体
        // 在实际应用中，可以返回一个更结构化的 JSON 对象
        return new ResponseEntity<>("请求参数校验失败：" + errorMessage, HttpStatus.BAD_REQUEST);
    }

    // 可以根据需要添加其他异常处理器，例如处理 MethodArgumentNotValidException
    // MethodArgumentNotValidException 通常在 @RequestBody 参数校验失败时抛出
    // @Override
    // protected ResponseEntity<Object> handleMethodArgumentNotValid(MethodArgumentNotValidException ex,
    //                                                               HttpHeaders headers,
    //                                                               HttpStatus status,
    //                                                               WebRequest request) {
    //     logger.error("Method Argument Not Valid Exception: {}", ex.getMessage(), ex);
    //     List<String> errors = ex.getBindingResult()
    //                             .getFieldErrors()
    //                             .stream()
    //                             .map(error -> error.getField() + ": " + error.getDefaultMessage())
    //                             .collect(Collectors.toList());
    //     return new ResponseEntity<>(errors, HttpStatus.BAD_REQUEST);
    // }
}