接口

接口是一种类型, 约定了要实现的方法列表, 可实现鸭子类型, 即看起来像鸭子, 叫起来像鸭子, 就是鸭子

定义接口

type Player interface {
	Runner // 接口嵌套
	Jumper
}

type Runner interface {
	run(speed int) (res string, canRun bool)
}

type Jumper interface {
	jump(height int) (res string, canJump bool)
}

结构体实现接口

type Pig struct {
	name string
}

func (p Pig) run(speed int) (res string, canRun bool) {
	return p.name + "'s speed is " + fmt.Sprint(speed) + "km/h", true
}

func (p Pig) jump(height int) (res string, canJump bool) {
	return p.name + " can jump " + fmt.Sprint(height) + "m hight", true
}

type Dog struct {
	name string
}

func (p Dog) run(speed int) (res string, canRun bool) {
	return p.name + "'s speed is " + fmt.Sprint(speed) + "km/h", true
}

func (p Dog) jump(height int) (res string, canJump bool) {
	return p.name + " can jump " + fmt.Sprint(height) + "m hight", true
}

接口应用

	pig := Pig{name: "Peggy"}
	runRes, canRun := pig.run(30)
	if canRun {
		fmt.Println(runRes) // Peggy's speed is 30km/h
	}
	var player Player
	player = pig
	jumpRes, canJump := player.jump(2)
	if canJump {
		fmt.Println(jumpRes) // Peggy can jump 2m hight
	}
	dog := Dog{name: "Wangcai"}
	player = dog
	runRes, canRun = dog.run(50)
	if canRun {
		fmt.Println(runRes) // Wangcai's speed is 50km/h
	}

内嵌结构体实现部分接口

// 洗剪吹
type WashCutBlow interface {
	wash()
	cut()
	blow()
}

type Blower struct {
}

func (b Blower) blow() {
	fmt.Println("I can blow~")
}
// 托尼老师
type TeacherTony struct {
	name string
	Blower
}

func (t TeacherTony) wash() {
	fmt.Println("I can wasg~")
}
func (t TeacherTony) cut()  {
	fmt.Println("I can cut~")
}

func main () {
        // 内嵌结构体实现部分接口
	var wcb WashCutBlow
	teacherTony := TeacherTony{name: "Tony"}
	wcb = teacherTony
	fmt.Println(wcb)
	wcb.blow() // I can blow~
}

空接口

类似ts中的any

// 空接口
	type EmptyInterface interface{}
	var x EmptyInterface
	x = 1
	fmt.Printf("type: %T, value: %#v \n", x, x) // type: int, value: 1
	x = "a"
	fmt.Printf("type: %T, value: %#v \n", x, x) // type: string, value: "a"
	x = 'a'
	fmt.Printf("type: %T, value: %#v \n", x, x) // type: int32, value: 97

	// 空接口应用, 类似ts中的any
	person := make(map[interface{}]interface{})
	person["age"] = 18
	person[false] = 1
	fmt.Printf("type: %T, value: %#v \n", person, person) // type: map[interface {}]interface {}, value: map[interface {}]interface {}{false:1, "age":18}

类型断言

类似js中的tyeof

	value, ok := x.(string)
	if ok {
		fmt.Printf("value: %#v \n", value)
	} else {
		fmt.Println("x is not string") // x is not string
	}
	x = "b"
	value, ok = x.(string)
	if ok {
		fmt.Printf("value: %#v \n", value) // value: "b"
	} else {
		fmt.Println("x is not string")
	}