Getting Started with java Simple Factory Mode

Table of Contents Preface Test Example 1. Create beverage interface (or abstract class) 2. Realization of specific beverage class (Coke, Sprite) 3. Beverage production factory class 4. Factory call summary

Preface

Define a factory class, which can return instances of different classes according to different parameters. The created instances usually have a common parent class

The method used to create an instance in a simple factory pattern is usually a static (static) method, so the simple factory pattern is called a static factory method (Static Factory Method) and only needs to pass in a correct parameter to get the desired object without knowing its implementation process

Example

Take beverage processing factory as an example

1. Create a drink interface (or abstract class)

public interface Drink {
    void production();
}

2. Realization of specific beverages (Coke, Sprite)

public class ColaDrinkProduction implements Drink{
    @Override
    public void production() {
        System.out.println(" Production of cola drinks ");
    }
}

public class SpriteDrinkProduction implements Drink{
    @Override
    public void production() {
        System.out.println(" Production of Sprite Beverage ");
    }
}

3. Beverage production factories

public class DrinkProductionFactory {
    public static Drink productionDrink(String type){
        switch (type){
            case "cloa":
                return new ColaDrinkProduction();
            default:
                return new SpriteDrinkProduction();
        }
    }
}

4. Factory call

What object needs to pass in the corresponding parameters

Drink cloa = DrinkProductionFactory.productionDrink("cloa");
 cloa.production();

Characteristic

It is a concrete class, not an interface abstract class. There is an important call method (productionDrink), which is usually static. Create a product with if or switch and return

Disadvantages

Poor expandability I want to add one kind of beverage. Besides adding one kind of beverage product, I also need to modify the factory method (adding the branch condition of 'Case'). So it is not only open to expansion, but also open to modification, which violates the open-closed principle

Summarize

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