GO学习笔记(8)

八. 接口

　　接口（interface）是一种类型.

　　8.1. 定义接口

// 定义接口: 接口只有方法声明，没有实现，没有数据字段。
type Mover interface {
    move()
}
type dog struct {
    name string
}
type pig struct {
    name string
}

// 实现接口(实现接口中的方法)
func (d dog)move()  {
    fmt.Println("dog:",d.name)
}
func (p pig)move()  {
    fmt.Println("pig:",p.name)
}
func interfaceDemo()  {
    var x Mover    // 接口类型的变量
    var y Mover // 接口类型的变量
    var wangcai = dog{name:"wangcai"}
    x = wangcai    // 'Mover' as 'move' method has a pointer receiver
    x.move()
    var fugui = &pig{name:"fugui"}
    y = fugui
    y.move()
}

　　8.2. 值接收者和引用接收者实现接口的区别

 

 

 

 

 

　　8.3. 面试题: 下面的代码是否能正确编译type People interface {

    Speak(string) string
}
type Stduent struct{}

func (stu *Stduent) Speak(think string) (talk string) {
    if think == "sb" {
        talk = "你是个大帅比"
    } else {
        talk = "您好"
    }
    return
}
func main() {
    var peo People = Stduent{}　　// 这里会报错: Cannot use 'Stduent{}' (type Stduent) as type People in assignment Type does not implement 'People' as 'Speak' method has a pointer receiver
　　 // 修改为 var peo People = &Stduent{}

    think := "bitch"
    fmt.Println(peo.Speak(think))
}

　　8.4. 空接口:  空接口类型的变量可以存储任意类型的变量

　　　　8.4.1. 定义

func nilInterface() {
    // 定义一个空接口x
    var x interface{}
    s := "傻X"
    x = s
    fmt.Printf("%T %v\n", x, x) // string 傻X
    a := 100
    x = a
    fmt.Printf("%T %v\n", x, x) // int 100
    b := true
    x = b
    fmt.Printf("%T %v\n", x, x) // bool true
}

　　　　8.4.2. 应用

func info(a interface{}) {
    fmt.Printf("%T %v\n", a, a)
}
func interfaceUse() {
    // 空接口作为参数可实现接受任意类型为参数的函数
    info(10)    // int 10
    info(10.2)  // float64 10.2
    info("傻X")  // string 傻X
    info(false) // bool false

    // 空接口作为map的值, 实现可保存任意值的map
    var People = make(map[string]interface{})
    People["name"] = "傻X"
    People["sex"] = 1
    People["married"] = true
    fmt.Println(People) // map[married:true name:傻X sex:1]
}