UML

classDiagram
    class Product {
<!--more-->
<<interface>>
        +operation()
    }
    class ConcreteProductA {
        +operation()
    }
    class ConcreteProductB {
        +operation()
    }
    class SimpleFactory {
        +createProduct(string) Product
    }
    Product <|.. ConcreteProductA
    Product <|.. ConcreteProductB
    SimpleFactory ..> Product
    SimpleFactory ..> ConcreteProductA
    SimpleFactory ..> ConcreteProductB

Go Sample

package main

import "fmt"

// Product 接口
type Product interface {
    Operation() string
}

// ConcreteProductA 结构体
type ConcreteProductA struct{}

func (p *ConcreteProductA) Operation() string {
    return "ConcreteProductA"
}

// ConcreteProductB 结构体
type ConcreteProductB struct{}

func (p *ConcreteProductB) Operation() string {
    return "ConcreteProductB"
}

// SimpleFactory 结构体
type SimpleFactory struct{}

func (f *SimpleFactory) CreateProduct(productType string) Product {
    switch productType {
    case "A":
        return &ConcreteProductA{}
    case "B":
        return &ConcreteProductB{}
    default:
        return nil
    }
}

func main() {
    factory := &SimpleFactory{}

    productA := factory.CreateProduct("A")
    fmt.Println(productA.Operation())

    productB := factory.CreateProduct("B")
    fmt.Println(productB.Operation())
}