Spring Boot中整型字段非数字输入的验证与异常处理策略

public class MyRequestDTO {
    @NotNull
    @Digits(integer = 4, fraction = 0, message = "Provide valid Year in the format YYYY")
    @Min(value = 1900, message = "Year must be greater than 1900")
    private Integer year;

    // Getters and Setters
}

import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.MethodArgumentNotValidException;
import org.springframework.web.bind.annotation.ControllerAdvice;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.method.annotation.MethodArgumentTypeMismatchException;
import com.fasterxml.jackson.databind.exc.MismatchedInputException;

import java.util.HashMap;
import java.util.Map;

@ControllerAdvice
public class GlobalExceptionHandler {

    /**
     * 处理GET请求路径变量或查询参数的类型转换错误
     * 例如：/api/resource?year=abc
     */
    @ExceptionHandler(MethodArgumentTypeMismatchException.class)
    public ResponseEntity<Map<String, String>> handleTypeMismatch(MethodArgumentTypeMismatchException ex) {
        Map<String, String> errors = new HashMap<>();
        String paramName = ex.getName();
        String requiredType = ex.getRequiredType() != null ? ex.getRequiredType().getSimpleName() : "unknown";
        String value = ex.getValue() != null ? ex.getValue().toString() : "null";
        String errorMessage = String.format("参数 '%s' 的值 '%s' 无效，期望类型为 '%s'。", paramName, value, requiredType);

        // 可以进一步检查ex.getCause()来获取更详细的原始异常信息
        if (ex.getCause() instanceof NumberFormatException) {
            errorMessage = String.format("参数 '%s' 必须是有效的数字，但接收到 '%s'。", paramName, value);
        }

        errors.put("error", errorMessage);
        return new ResponseEntity<>(errors, HttpStatus.BAD_REQUEST);
    }

    /**
     * 处理请求体（如JSON）的类型转换错误
     * 例如：POST请求体中 {"year": "abc"}
     */
    @ExceptionHandler(MismatchedInputException.class)
    public ResponseEntity<Map<String, String>> handleMismatchedInput(MismatchedInputException ex) {
        Map<String, String> errors = new HashMap<>();
        String fieldName = ex.getPath().stream()
                               .map(p -> p.getFieldName() != null ? p.getFieldName() : "[" + p.getIndex() + "]")
                               .reduce((a, b) -> a + "." + b)
                               .orElse("未知字段");

        String errorMessage = String.format("字段 '%s' 的输入格式不匹配，期望类型为数字。", fieldName);
        errors.put("error", errorMessage);
        return new ResponseEntity<>(errors, HttpStatus.BAD_REQUEST);
    }

    /**
     * 处理Bean Validation失败的异常
     * （与本教程主题直接相关，但作为完整异常处理器的补充）
     */
    @ExceptionHandler(MethodArgumentNotValidException.class)
    public ResponseEntity<Map<String, String>> handleValidationExceptions(MethodArgumentNotValidException ex) {
        Map<String, String> errors = new HashMap<>();
        ex.getBindingResult().getFieldErrors().forEach(error -> 
            errors.put(error.getField(), error.getDefaultMessage()));
        return new ResponseEntity<>(errors, HttpStatus.BAD_REQUEST);
    }

    // 可以添加更多通用的异常处理器
    @ExceptionHandler(Exception.class)
    public ResponseEntity<Map<String, String>> handleAllOtherExceptions(Exception ex) {
        Map<String, String> errors = new HashMap<>();
        errors.put("error", "服务器内部错误：" + ex.getMessage());
        return new ResponseEntity<>(errors, HttpStatus.INTERNAL_SERVER_ERROR);
    }
}

import javax.validation.constraints.Pattern;
import javax.validation.constraints.Size;

public class MyRequestDTO {
    // 允许接收任何字符串，并通过正则表达式验证其是否为4位数字
    @Pattern(regexp = "^\d{4}$", message = "Year must be a 4-digit number.")
    private String yearString;

    // 手动提供一个转换为Integer的getter
    public Integer getYear() {
        if (yearString == null || yearString.isEmpty()) {
            return null; // 或者抛出IllegalArgumentException，根据业务需求
        }
        try {
            return Integer.parseInt(yearString);
        } catch (NumberFormatException e) {
            // 理论上，如果@Pattern验证通过，这里不应该抛出异常
            // 但作为防御性编程，可以处理
            throw new IllegalArgumentException("Invalid year format after validation: " + yearString);
        }
    }

    public String getYearString() {
        return yearString;
    }

    public void setYearString(String yearString) {
        this.yearString = yearString;
    }
}