Design pattern simple factory

Design Patterns After the previous article about the singleton pattern, I finally want to continue writing. Let’s start with the simplest one, the simple factory pattern. This design pattern is very simple and the most commonly used (isn’t it the same with many things? , the simpler, the lower the threshold and the more likable it is).

Concept (forgive me for shamelessly copying Baidu Encyclopedia):

The simple factory pattern is a creational pattern, also called the static factory method (Static Factory Method) pattern, but it does not belong to the 23 types of GOF One of the design patterns. The simple factory pattern uses a factory object to determine which product class instance is created. The simple factory pattern is the simplest and most practical pattern in the factory pattern family and can be understood as a special implementation of different factory patterns.

What is said here is very clear. A factory has N objects. This is the essence of a simple factory. The specific UML class diagram is as follows

First download the online tool Processon. This is my invitation link. Of course, if you need to draw a lot of pictures, please spend money to support them.

Let’s explain this class diagram. It consists of three parts. One is Creator, which is the factory class, the second is the IProduct interface, and the third is the specific products A and B.

The specific code is as follows

Product interface:

public interface IProduct {void meathod();
}

Specific product:

public class ProductA implements IProduct {public void meathod() {
        System.out.printf("产品A");
    }
}

public class ProductB implements IProduct {public void meathod() {
        System.out.printf("产品B");
    }
}

Factory:

public class Creator {public static IProduct createProduct(String productName) {if (null == productName) {return null;
        } else if ("A".equals(productName)) {return new ProductA();
        } else if ("B".equals(productName)) {return new ProductB();
        }return null;
    }public static void main(String[] args) {
        IProduct productA = Creator.createProduct("A");
        productA.meathod();

        IProduct productB = Creator.createProduct("B");
        productB.meathod();
    }
}

Output: Product A Product B

Specific example:

Such a simple model is relatively common. Take our project as an example. The products we make use various interfaces from multiple partners. Most of the interfaces are the same, but the specific fields and details are different. , for example, when applying for credit, all you need is some personal privacy information. What each company wants is roughly the same, but individual information is different. This is very suitable for the factory model.

Advantages and disadvantages:

Advantages: decoupling, helping encapsulation.

Disadvantages: Increases the complexity of the client, which is not conducive to expanding sub-factories

In fact, the essence of the simple factory pattern is to choose to implement it.

Let’s just say this and so much.

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