Go设计模式之生成器模式详细讲解

时间:2023-02-03 Ch3n 人气:0

生成器模式

生成器是一种创建型设计模式，使你能够分步骤创建复杂对象。

与其他创建型模式不同，生成器不要求产品拥有通用接口。这使得用相同的创建过程生成不同的产品成为可能。

概念示例

当所需产品较为复杂且需要多个步骤才能完成时，也可以使用生成器模式。在这种情况下，使用多个构造方法比仅仅使用一个复杂可怕的构造函数更简单。分为多个步骤进行构建的潜在问题是，构建不完整的和不稳定的产品可能会被暴露给客户端。生成器模式能够在产品完成构建之前使其处于私密状态。

在下方的代码中，我们可以看到 iglooBuilder冰屋生成器与 normalBuilder普通房屋生成器可建造不同类型房屋，即 igloo冰屋和 normalHouse普通房屋。每种房屋类型的建造步骤都是相同的。主管（可选）结构体可对建造过程进行组织。

iBuilder.go: 生成器接口

package main
type IBuilder interface {
    setWindowType()
    setDoorType()
    setNumFloor()
    getHouse() House
}
func getBuilder(builderType string) IBuilder {
    if builderType == "normal" {
        return newNormalBuilder()
    }
    if builderType == "igloo" {
        return newIglooBuilder()
    }
    return nil
}

normalBuilder.go: 具体生成器

package main
type NormalBuilder struct {
    windowType string
    doorType   string
    floor      int
}
func newNormalBuilder() *NormalBuilder {
    return &NormalBuilder{}
}
func (b *NormalBuilder) setWindowType() {
    b.windowType = "Wooden Window"
}
func (b *NormalBuilder) setDoorType() {
    b.doorType = "Wooden Door"
}
func (b *NormalBuilder) setNumFloor() {
    b.floor = 2
}
func (b *NormalBuilder) getHouse() House {
    return House{
        doorType:   b.doorType,
        windowType: b.windowType,
        floor:      b.floor,
    }
}

iglooBuilder.go: 具体生成器

package main
type IglooBuilder struct {
    windowType string
    doorType   string
    floor      int
}
func newIglooBuilder() *IglooBuilder {
    return &IglooBuilder{}
}
func (b *IglooBuilder) setWindowType() {
    b.windowType = "Snow Window"
}
func (b *IglooBuilder) setDoorType() {
    b.doorType = "Snow Door"
}
func (b *IglooBuilder) setNumFloor() {
    b.floor = 1
}
func (b *IglooBuilder) getHouse() House {
    return House{
        doorType:   b.doorType,
        windowType: b.windowType,
        floor:      b.floor,
    }
}

house.go: 产品

package main

type House struct {
    windowType string
    doorType   string
    floor      int
}

director.go: 主管

package main
type Director struct {
    builder IBuilder
}
func newDirector(b IBuilder) *Director {
    return &Director{
        builder: b,
    }
}
func (d *Director) setBuilder(b IBuilder) {
    d.builder = b
}
func (d *Director) buildHouse() House {
    d.builder.setDoorType()
    d.builder.setWindowType()
    d.builder.setNumFloor()
    return d.builder.getHouse()
}

main.go: 客户端代码

package main
import "fmt"
func main() {
    normalBuilder := getBuilder("normal")
    iglooBuilder := getBuilder("igloo")
    director := newDirector(normalBuilder)
    normalHouse := director.buildHouse()
    fmt.Printf("Normal House Door Type: %s\n", normalHouse.doorType)
    fmt.Printf("Normal House Window Type: %s\n", normalHouse.windowType)
    fmt.Printf("Normal House Num Floor: %d\n", normalHouse.floor)
    director.setBuilder(iglooBuilder)
    iglooHouse := director.buildHouse()
    fmt.Printf("\nIgloo House Door Type: %s\n", iglooHouse.doorType)
    fmt.Printf("Igloo House Window Type: %s\n", iglooHouse.windowType)
    fmt.Printf("Igloo House Num Floor: %d\n", iglooHouse.floor)
}

output.txt: 执行结果

Normal House Door Type: Wooden Door
Normal House Window Type: Wooden Window
Normal House Num Floor: 2

Igloo House Door Type: Snow Door
Igloo House Window Type: Snow Window
Igloo House Num Floor: 1

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