Exemplo de Factory Method

Patterns - Abstract Factory

Contexto Um sistema recebe arquivos de parceiros diferentes:

• Laboratórios
• Convênios
• ERPs externos

Cada parceiro manda em um formato diferente, mas o fluxo é sempre:

1. Abrir arquivo
2. Validar
3. Processar
4. Persistir

De-Para das classes

GoF	Exemplo
Product	ImportProcessor
ConcreteProduct	CsvImportProcessor, XmlImportProcessor, JsonImportProcessor
Creator	ImportService
ConcreteCreator	CsvImportService, XmlImportService

Código

// produto abstrato
public abstract class ImportProcessor
{
    public abstract void Validate(string filePath);
    public abstract void Process(string filePath);
}

// produtos concretos
public class CsvImportProcessor : ImportProcessor
{
    public override void Validate(string filePath)
    {
        Console.WriteLine("Validating CSV file");
    }

    public override void Process(string filePath)
    {
        Console.WriteLine("Processing CSV file");
    }
}

public class XmlImportProcessor : ImportProcessor
{
    public override void Validate(string filePath)
    {
        Console.WriteLine("Validating XML file");
    }

    public override void Process(string filePath)
    {
        Console.WriteLine("Processing XML file");
    }
}

public class JsonImportProcessor : ImportProcessor
{
    public override void Validate(string filePath)
    {
        Console.WriteLine("Validating JSON file");
    }

    public override void Process(string filePath)
    {
        Console.WriteLine("Processing JSON file");
    }
}

// Creator
public abstract class ImportService
{
	// o processamento sempre segue igual
    public void Import(string filePath)
    {
        var processor = CreateProcessor();

        processor.Validate(filePath);
        processor.Process(filePath);

        Console.WriteLine("Import finished");
    }

    // 🔥 FACTORY METHOD
    protected abstract ImportProcessor CreateProcessor();
}

// concrete creators
public class CsvImportService : ImportService
{
    protected override ImportProcessor CreateProcessor()
    {
        return new CsvImportProcessor();
    }
}

public class XmlImportService : ImportService
{
    protected override ImportProcessor CreateProcessor()
    {
        return new XmlImportProcessor();
    }
}

public class JsonImportService : ImportService
{
    protected override ImportProcessor CreateProcessor()
    {
        return new JsonImportProcessor();
    }
}

// Controller

// [...]
// concrete creator para csv
ImportService service = new CsvImportService();
service.Import("file.csv");

// concrete creator mas agora para json
service = new JsonImportService();
service.Import("file.json");

// [...]

Referências

• Chat GPT