深入理解Golang之interface

深藏阁楼爱情的钟 2023-02-14 01:38 13阅读 0赞

### **1. interface:简单的说，interface是一组method的组合，我们通过interface来定义对象的一组行为。** ###

**参考下面这个例子：**

package main
     
    import "fmt"
     
    type Human interface {
        speak(language string)
    }
     
    type Chinese struct {
    }
     
    type American struct {
    }
     
    func (ch Chinese) speak(language string ) {
      fmt.Printf("speck %s\n",language)
    }
     
    func (am American ) speak(language string ) {
      fmt.Printf("speck %s\n",language)
    }
     
    func main() {
        var ch Human
        var am Human
     
        ch = Chinese{}
        am = American{}
     
        ch.speak("Chinese")
        am.speak("English")
    }

###       ** 2. 空interface** ###

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3k1MzI3OTgxMTM_size_16_color_FFFFFF_t_70][]

### 3.interface变量存储的类型 ###

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3k1MzI3OTgxMTM_size_16_color_FFFFFF_t_70 1][]

package main
    import (
      "fmt"
      "strconv"
    )
    
    type Element interface{}
    type List [] Element
    
    type Person struct {
         name string
         age int
    }
    //打印
    func (p Person) String() string {
       return "(name: " + p.name + " - age: "+strconv.Itoa(p.age)+ " years)"
    }
    func main() {
    
      list := make(List, 3)
      list[0] = 1 //an int
      list[1] = "Hello" //a string
      list[2] = Person{"Dennis", 70}
    
      for index, element := range list{
      switch value := element.(type) {
      case int:
        fmt.Printf("list[%d] is an int and its value is %d\n", index, value)
      case string:
        fmt.Printf("list[%d] is a string and its value is %s\n", index, value)
      case Person:
        fmt.Printf("list[%d] is a Person and its value is %s\n", index, value)
      default:
        fmt.Println("list[%d] is of a different type", index)
      }
    }

需要注意：element.(type)语法不能在switch外的任何逻辑里面使用，如果你要在switch外面判断一个类型就使用comma-ok

### 4. 嵌入interface ###

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3k1MzI3OTgxMTM_size_16_color_FFFFFF_t_70 2][]

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