一、简介

门面模式，也叫外观模式，英文全称是Facade Design Pattern。门面模式为子系统提供一组统一的接口，定义一组高层接口让子系统更易用。

目的：简化复杂系统的交互方式

特点：提供一个统一的交互接口

二、UML类图

三、案例

以下案例是家庭影院，家庭影院中有各种播放设备，如DVD、音响等，整体对外提供看电影和关闭的功能。

package main

import "fmt"

type Projecter struct {
}

func (Projecter) On() {
    fmt.Println("Turning on the projecter...")
}

func (Projecter) Off() {
    fmt.Println("Turning off the projecter...")
}

type DVDPlayer struct {
}

func (DVDPlayer) Play() {
    fmt.Println("Playing the DVDPlayer...")
}

func (DVDPlayer) Stop() {
    fmt.Println("Stopping the DVDPlayer...")
}

type SoundSystem struct {
}

func (SoundSystem) On() {
    fmt.Println("Turning on the sound system...")
}

func (SoundSystem) Off() {
    fmt.Println("Turning off the sound system...")
}

type HomeTheaterFacade struct {
    Projecter Projecter
    DVDPlayer DVDPlayer
    SoundSystem SoundSystem
}

func NewHomeTheaterFacade(projecter Projecter, dvdPlayer DVDPlayer, soundSystem SoundSystem) HomeTheaterFacade {
    homeTheaterFacade := HomeTheaterFacade{}
    homeTheaterFacade.Projecter = projecter
    homeTheaterFacade.DVDPlayer = dvdPlayer
    homeTheaterFacade.SoundSystem = soundSystem
    return homeTheaterFacade
}

func (htf HomeTheaterFacade) WatchMovie() {
    htf.Projecter.On()
    htf.DVDPlayer.Play()
    htf.SoundSystem.On()
}

func (htf HomeTheaterFacade) StopMovie() {
    htf.Projecter.Off()
    htf.DVDPlayer.Stop()
    htf.SoundSystem.Off()
}

func main() {
    projecter := Projecter{}
    dvdPlayer := DVDPlayer{}
    soundSystem := SoundSystem{}
   	homeTheaterFacade := NewHomeTheaterFacade(projecter, dvdPlayer, soundSystem)
  	homeTheaterFacade.WatchMovie()
  	homeTheaterFacade.StopMovie()
}