命令模式(behavioral 2)

3.2 命令模式(command)

• 将来自客户端的请求传入一个对象，从而使你可用不同的请求对客户进行参数化。用于“行为请求者”与“行为实现者”解耦，可实现二者之间的松耦合，以便适应变化。分离变化与不变的因素。
• 请求以命令的形式包裹在对象中，并传给调用对象。调用对象寻找可以处理该命令的合适的对象，并把该命令传给相应的对象，该对象执行命令。
• 定义三个角色
  • Command 定义命令的接口，声明执行的方法。
    • ConcreteCommand 命令接口实现对象，是“虚”的实现；通常会持有接收者，并调用接收者的功能来完成命令要执行的操作。
  • Receiver 接收者，真正执行命令的对象。
  • Invoker 使用对象命令的入口 调用者 - Client 创建具体的命令对象，并且设置命令对象的接收者。 整体流程 定义三个角色,command 属于驾驶舱 receiver 属于涡轮 invoker 调用实际命令的入口；先创建具体的 receiver 将 receiver 传入到 invoker 调用者,最后 command 调用 invoker 处理对应的命令 执行,具体的状态 receiver 会发生变化

//驾驶舱 接受命令 执行命令 command
function Cockpit(command) {
	this.command = command
}
Cockpit.prototype.execute = function () {
	this.command.execute()
}

//涡轮  操作有开 关 加速 减速 receiver 命令真正执行的对象
function Turbine() {
	this.state = false
	this.speed = 0
}
Turbine.prototype.on = function () {
	this.state = true
	this.speed = 100
}
Turbine.prototype.off = function () {
	this.state = false
	this.speed = 0
}
Turbine.prototype.speedDown = function () {
	if (!this.state) return
	this.speed -= 100
}
Turbine.prototype.speedUp = function () {
	if (!this.state) return
	this.speed += 100
}
//命令 操作开命令 调用turbine实例的开
// invoker 使用命令对象的入口
function OnCommand(turbine) {
	this.turbine = turbine
}
OnCommand.prototype.execute = function () {
	this.turbine.on()
}

function OffCommand(turbine) {
	this.turbine = turbine
}
OffCommand.prototype.execute = function () {
	this.turbine.off()
}

function SpeedUpCommand(turbine) {
	this.turbine = turbine
}
SpeedUpCommand.prototype.execute = function () {
	this.turbine.speedUp()
}

function SpeedDownCommand(turbine) {
	this.turbine = turbine
}
SpeedDownCommand.prototype.execute = function () {
	this.turbine.speedDown()
}

module.exports = [Cockpit, Turbine, OffCommand, OnCommand, SpeedDownCommand, SpeedUpCommand]

const expect = require('chai').expect
const [Cockpit, Turbine, OffCommand, OnCommand, SpeedDownCommand, SpeedUpCommand] = require('../src/behavioral/command/command.js')

describe('命令模式 测试', () => {
	it('开/关 测试', () => {
		//receiver 创建命令的具体对象 涡轮  真正命令执行的对象
		var turbine = new Turbine()
		//invoker 调用者 使用命令对象入口
		const onCommand = new OnCommand(turbine)
		//command 驾驶舱
		const cockpit = new Cockpit(onCommand)
		cockpit.execute()
		expect(turbine.state).to.be.true
	})
	it('加减速 测试', () => {
		//先开启后加速
		var turbine = new Turbine()
		const onCommand = new OnCommand(turbine)
		var cockpit = new Cockpit(onCommand)
		cockpit.execute()

		const speedUpCommand = new SpeedUpCommand(turbine)
		cockpit = new Cockpit(speedUpCommand)
		cockpit.execute()
		expect(turbine.speed).to.equal(200)
	})
})

es6 实现

class Cockpit {
	constructor(command) {
		this.command = command
	}
	execute() {
		this.command.execute()
	}
}

class Turbine {
	constructor() {
		this.state = false
		this.speed = 0
	}
	on() {
		this.state = true
		this.speed = 100
	}
	off() {
		this.state = false
		this.speed = 0
	}
	speedDown() {
		if (!this.state) return
		this.speed -= 100
	}
	speedUp() {
		if (!this.state) return
		this.speed += 100
	}
}

class OnCommand {
	constructor(turbine) {
		this.turbine = turbine
	}
	execute() {
		this.turbine.on()
	}
}
class OffCommand {
	constructor(turbine) {
		this.turbine = turbine
	}
	execute() {
		this.turbine.off()
	}
}
class SpeedUpCommand {
	constructor(turbine) {
		this.turbine = turbine
	}
	execute() {
		this.turbine.speedUp()
	}
}
class SpeedDownCommand {
	constructor(turbine) {
		this.turbine = turbine
	}
	execute() {
		this.turbine.speedDown()
	}
}

export { Cockpit, Turbine, OffCommand, OnCommand, SpeedDownCommand, SpeedUpCommand }

const expect = require('chai').expect
import { Cockpit, Turbine, OffCommand, OnCommand, SpeedDownCommand, SpeedUpCommand } from '../src/behavioral/command/command_es6'

describe('命令模式 es6测试', () => {
	it('开/关 测试', () => {
		//receiver 创建命令的具体对象 涡轮  真正命令执行的对象
		var turbine = new Turbine()
		//invoker 调用者 使用命令对象入口
		const onCommand = new OnCommand(turbine)
		//command 驾驶舱
		const cockpit = new Cockpit(onCommand)
		cockpit.execute()
		expect(turbine.state).to.be.true
	})
	it('加减速 测试', () => {
		//先开启后加速
		var turbine = new Turbine()
		const onCommand = new OnCommand(turbine)
		var cockpit = new Cockpit(onCommand)
		cockpit.execute()

		const speedUpCommand = new SpeedUpCommand(turbine)
		cockpit = new Cockpit(speedUpCommand)
		cockpit.execute()
		expect(turbine.speed).to.equal(200)
	})
})