[英]Refactoring business logic validation
我正在嘗試重構此代碼
private void validate(Customer customer) {
List<String> errors = new ArrayList<>();
if (customer == null) {
errors.add("Customer must not be null");
}
if (customer != null && customer.getName() == null) {
errors.add("Name must not be null");
}
if (customer != null && customer.getName().isEmpty()) {
errors.add("Name must not be empty");
}
if (customer != null) {
Customer customerFromDb = customerRepository.findByName(customer.getName());
if (customerFromDb != null) {
errors.add("Customer already present on db");
}
}
if (!errors.isEmpty()) {
throw new ValidationException(errors);
}
}
我讀了這篇文章業務邏輯驗證模式和建議
我想為我的實體和實體字段構建通用驗證器,我寫了這個
private void validate(Customer customer) {
List<ValidationRule> validationRules = new ArrayList<>();
validationRules.add(new NotNullValidationRule(customer));
validationRules.add(new NotNullValidationRule(customer, Customer::getName));
validationRules.add(new NotEmptyValidationRule(customer, Customer::getName));
validationRules.add(new NotExistValidationRule(customer -> customerRepository.findByName(customer.getName())));
Validator.validate(validationRules);
}
和Validator類
public class Validator {
public static void validate(List<ValidationRule> validationRules) {
final List<String> errors = new ArrayList<>();
for (final ValidationRule rule : validationRules) {
final Optional<String> error = rule.validate();
if (error.isPresent()) {
errors.add(error.get());
}
}
if (!errors.isEmpty()) {
throw new ValidationException(errors);
}
}
}
但我不知道如何實現接口ValidationRule和其他類(NotNullValidationRule,NotEmptyValidationRule,NotExistValidationRule)
我會寫類似:
CommonValidations.notNull(errors, customer);
if (customer != null) {
CommonValidations.notEmpty(errors, customer.getName());
}
customerCustomeBeanValidations.validName(errors, customer.getName());
customerCustomeBeanValidations.notExist(errors, customer.getName());
在您參考的鏈接中,建議使用策略設計模式回答可接受的問題,然后給出界面和實現的示例。 在您的情況下,您將使用至少一個方法validate()創建一個新的接口ValidationRule,然后創建每個在該接口上實現的具體類(NotNullValidationRule,NotEmptyValidationRule,AlreadyExistValidationRule)。
我找到了這個解決方案:
我創建一個接口ValidationRule
import java.util.Optional;
public interface ValidationRule {
Optional<ValidationError> validate();
}
還有一些實現行為的類
public class NotNullValidationRule implements ValidationRule {
private Object object;
private String field;
public NotNullValidationRule(Object object, String field) {
this.object = object;
if (field == null || field.isEmpty()) {
throw new IllegalArgumentException("field must not be null or emtpy");
}
this.field = field;
}
@Override public Optional<ValidationError> validate() {
if (object == null) {
return Optional.empty();
}
try {
Object value = new PropertyDescriptor(field, object.getClass()).getReadMethod().invoke(object);
if (value == null) {
ValidationError validationError = new ValidationError();
validationError.setName(object.getClass().getSimpleName() + "." + field);
validationError.setError("Field " + field + " is null");
return Optional.of(validationError);
}
}
catch (Exception e) {
throw new IllegalStateException("error during retrieve of field value");
}
return Optional.empty();
}
}
另一個我傳遞方法調用的地方:
package it.winetsolutions.winactitime.core.service.validation;
import java.beans.PropertyDescriptor;
import java.util.Optional;
import java.util.function.Function;
public class NotExistValidationRule implements ValidationRule {
Object object;
String field;
Function<? super String, ? super Object> function;
public NotExistValidationRule(Object object, String field, Function<? super String, ? super Object> function) {
this.object = object;
if (field == null || field.isEmpty() || function == null) {
throw new IllegalArgumentException("field and function must not be null or emtpy");
}
this.field = field;
this.function = function;
}
@Override public Optional<ValidationError> validate() {
if (object == null) {
return Optional.empty();
}
try {
Object value = new PropertyDescriptor(field, object.getClass()).getReadMethod().invoke(object);
Long id = (Long) new PropertyDescriptor("id", object.getClass()).getReadMethod().invoke(object);
Object result = function.apply(value == null ? (String) value : ((String) value).trim());
if (result != null &&
!id.equals((Long) new PropertyDescriptor("id", result.getClass()).getReadMethod().invoke(result))) {
ValidationError validationError = new ValidationError();
validationError.setName(object.getClass().getSimpleName() + "." + field);
validationError.setError("Element with " + field +": " + value + " already exists");
return Optional.of(validationError);
}
}
catch (Exception e) {
throw new IllegalStateException("error during retrieve of field value");
}
return Optional.empty();
}
}
聲明:本站的技術帖子網頁,遵循CC BY-SA 4.0協議,如果您需要轉載,請注明本站網址或者原文地址。任何問題請咨詢:yoyou2525@163.com.