Go学习:接口的值类型

接口的值类型"/>

Go学习:接口的值类型

接口变量

接口的定义和实现

main

package mainimport ("fmt""learngo/retriever/mock""learngo/retriever/test""time"
)type Retriever interface {Get(url string) string
}func download(r Retriever) string {return r.Get("=1001.2014.3001.5502")
}func main() {r := mock.Retriever{"番茄炒蛋",time.Minute}// HTTP/2.0 200 OKfmt.Println(download(r))rr  := test.Retriever{"this is fake contents"}// this is fake contentsfmt.Println(download(rr))
}

mock.Retriever

package mockimport ("net/http""net/http/httputil""time"
)type Retriever struct {UserAgrent stringTimeOut       time.Duration
}func (r Retriever) Get(url string) string {resp, err := http.Get(url)if err != nil {panic(err)}defer resp.Body.Close()bytes, err := httputil.DumpResponse(resp, true)if err != nil {panic(err)}return string(bytes)
}

test.Retriever

package testtype Retriever struct {Contents string
}func (r Retriever) Get(url string) string {return r.Contents
}

接口变量内容

package mainimport ("fmt""learngo/retriever/mock""learngo/retriever/test""time"
)type Retriever interface {Get(url string) string
}func download(r Retriever) string {return r.Get("=1001.2014.3001.5502")
}func main() {r := mock.Retriever{"番茄炒蛋", time.Minute}// HTTP/2.0 200 OK//fmt.Println(download(r))// mock.Retriever {番茄炒蛋 1m0s}fmt.Printf("%T %v\n", r, r)rr := test.Retriever{"this is fake contents"}// this is fake contents//fmt.Println(download(rr))// test.Retriever {this is fake contents}fmt.Printf("%T %v\n", rr, rr)
}

r和rr里面有一个类型,和自己真实的value

通过指针访问

mock.Retriever

package mockimport ("net/http""net/http/httputil""time"
)type Retriever struct {UserAgrent stringTimeOut       time.Duration
}func (r *Retriever) Get(url string) string {resp, err := http.Get(url)if err != nil {panic(err)}defer resp.Body.Close()bytes, err := httputil.DumpResponse(resp, true)if err != nil {panic(err)}return string(bytes)
}

main

package mainimport ("fmt""learngo/retriever/mock""learngo/retriever/test""time"
)type Retriever interface {Get(url string) string
}func download(r Retriever) string {return r.Get("=1001.2014.3001.5502")
}func main() {r := &mock.Retriever{"番茄炒蛋", time.Minute}// HTTP/2.0 200 OK//fmt.Println(download(r))// *mock.Retriever &{番茄炒蛋 1m0s}fmt.Printf("%T %v\n", r, r)rr := test.Retriever{"this is fake contents"}// this is fake contents//fmt.Println(download(rr))// test.Retriever {this is fake contents}fmt.Printf("%T %v\n", rr, rr)
}

获取接口的类型

case方式访问

package mainimport ("fmt""learngo/retriever/mock""learngo/retriever/test""time"
)type Retriever interface {Get(url string) string
}func download(r Retriever) string {return r.Get("=1001.2014.3001.5502")
}func main() {var r Retriever = &mock.Retriever{"番茄炒蛋", time.Minute}// HTTP/2.0 200 OK//fmt.Println(download(r))// UserAgent: 番茄炒蛋funcName(r)if mockRetriever, ok := r.(*mock.Retriever); ok {// TimeOut: 1m0sfmt.Println("TimeOut:", mockRetriever.TimeOut)}else {fmt.Println("not a mock Retriever")}r = test.Retriever{"this is fake contents"}// this is fake contents//fmt.Println(download(rr))// ontents: this is fake contentsfuncName(r)}func funcName(r Retriever) {switch v := r.(type) {case *mock.Retriever:fmt.Println("UserAgent:", v.UserAgrent)case test.Retriever:fmt.Println("contents:", v.Contents)}
}

• 接口变量自带指针
• 接口变量同样采用值传递,因为接口变量里面有一个指针,所以几乎不需要使用接口的指针
• 指针接收者实现只能以指针的方式来使用;值接收者两者都可以

查看接口变量

• Type Assertion
• Type Switch
• 表示任何类型:interface{} (go语言任何类型表示法)