问ValidationRule中的WPF依赖注入

EN

public class ExternalServiceValidationRule : ValidationRule
{
    private readonly IValidationService _validationService;

    public ExternalServiceValidationRule (IValidationService validationService)
    {
        _validationService = validationService;
    }

    public override ValidationResult Validate(object value, CultureInfo cultureInfo)
    {
        // simplified code
        return _validationService.Validate(value);
    }
}