Domain Design : Repository Implementation

Реализация репозитория 

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

/**
 * Для инстационирования и временного сохранения репозитория
 * @author oleksandr.zakharov

 */
public final class RepositoryFactory {

    private Repository repository;
    
    private static Map<String,Repository> repositoryMap = new HashMap<String,Repository>();
    
    private RepositoryFactory(){
        repository = new Repository();
    }
    
    public static RepositoryFactory createRepository(){
        RepositoryFactory repositoryFactory = new RepositoryFactory();  
        return repositoryFactory;
    }
    
    public RepositoryFactory addName(String name){
        repository.setName(name);
        return this;
    }
    
    public RepositoryFactory addSpecification(Specification s){
        repository.getSpecifications().add(s);
        return this;
    }
    
    public static Repository findRepository(String name){
        return repositoryMap.get(name);
    }
    
    public Repository buildAll(){
        repositoryMap.put(repository.getName(), repository);
        return repository;
    }
    
}

Определяем спецификацию репозитория

package repository;

/**
 *
 * @author oleksandr.zakharov
 */
public interface Specification {
    
    boolean validate(IEntity entity);
    
}

Сам репозиторий со спецификациями

package repository;

import java.util.ArrayList;
import java.util.List;

/**
 *
 * @author oleksandr.zakharov
 * @param <T>
 */
public class Repository<T extends IEntity> {

    public Repository() {
        ts = new ArrayList<>();
        specifications = new ArrayList<>();
    }
    
    private boolean validate(IEntity entity){
        for(Specification s: specifications){
            if(!s.validate(entity)) return false;
        }
        return true;
    }
    
    private String name;
    
    private List<Specification> specifications;
    
    private List<T> ts; 

    List<Specification> getSpecifications() {
        return specifications;
    }

    String getName() {
        return name;
    }

    void setName(String name) {
        this.name = name;
    }
    
    public boolean save(T entity){
        if(validate(entity)){
            ts.add(entity);
            return true;
        }
        return false;
    }
}

интерфейс сущности 

package repository;

/**
 *
 * @author oleksandr.zakharov
 */
public interface IEntity {
    
    Long getId();
    
}

Небольшая реализация(счет продукта не должен быть больше 40)

package repository.impl;

import repository.IEntity;
import repository.Specification;

/**
 *
 * @author oleksandr.zakharov
 */
public class AmountSpec implements Specification{

    @Override
    public boolean validate(IEntity entity) {
        Product p = (Product) entity;
        return p.getAmount() > 40;
    }        
}

package repository.impl;

import repository.IEntity;

/**
 *
 * @author oleksandr.zakharov
 */
public class Product implements IEntity{
    
    private Long id;
    
    private double amount;

    @Override
    public Long getId() {
        return id;
    }

    public double getAmount() {
        return amount;
    }

    public void setAmount(double amount) {
        this.amount = amount;
    }
    
}

package repository.impl;

import repository.Repository;
import repository.RepositoryFactory;

/**
 *
 * @author oleksandr.zakharov Simple example
 */
public class TestMain {

    public static void main(String[] str) {
        RepositoryFactory
                .createRepository()
                .addName("Repository")
                .addSpecification(new AmountSpec()) // i added for specific repository
                .buildAll();
        Repository r = RepositoryFactory.findRepository("Repository");
        Product product = new Product();
        product.setAmount(40);
        System.out.print(r.save(product)); // если меньше сорока не сохраниться

    }

}