Create - configure factory

You may encounter “ Configuration factory ” This kind of practice , This is not a design pattern , The general implementation idea is to configure the object to be created to properties In file , Then read the configuration file , Use reflection to create objects stored in a static global variable , Then, when the client gets it, it can get it from the global object .

One ：entity

public abstract class Coffee {
    
    public abstract String getName();
}

public class AmericanCoffee extends Coffee {
    
    @Override
    public String getName() {
    
        return " Cafe Americano （ American flavor ）";
    }
}

public class LatteCoffee extends Coffee {
    
    @Override
    public String getName() {
    
        return " Cafe Latte （ Italian flavor ）";
    }
}

Two ：bean.properties

American=com.example.design.AmericanCoffee
Latte=com.example.design.LatteCoffee

3、 ... and ：ConfigFactory

public class CoffeeConfigFactory {
    
    private static Map<String, Coffee> coffeeMap = new HashMap<>();

    static {
    
        InputStream inputStream = CoffeeConfigFactory.class.getClassLoader().getResourceAsStream("bean.properties");
        Properties properties = new Properties();
        try {
    
            properties.load(inputStream);
            for (Object key : properties.keySet()) {
    
                String classFullName = (String) properties.get(key);
                Coffee coffee = (Coffee)Class.forName(classFullName).newInstance();
                coffeeMap.put((String) key, coffee);
            }
        } catch (Exception e) {
    
            e.printStackTrace();
        }
    }

    public static Coffee createCoffee(String name) {
    
        return coffeeMap.get(name);
    }
}

Four ：Main

public static void main(String[] args) {
    
    Coffee coffee = CoffeeConfigFactory.createCoffee("Latte");
    System.out.println(coffee.getName());
}

5、 ... and ： Comparison with factory method design pattern

• When adding an object, the factory method pattern needs to add a corresponding factory class file , To configure a factory, you only need to add a new configuration in the configuration file , This is easier .
• The configuration factory will create all objects that will be permanently stored in memory and will not be recycled when the project is started , Exchange memory for convenience .