Go 接口

package main

import (
    "awesomeProject/retriever/mock"
    "awesomeProject/retriever/real"
    "fmt"
    "time"
)

//接口由使用者定义
//接口的实现是隐式的，只要实现接口里的方法
//接口变量自带指针
//接口变量采用值传递，几乎不需要使用接口的指针
//指针接收者实现只能以指针方式使用，值接收者都可
//查看接口变量:
//             表示任何类型 :interface{}
//             Type Assertion
//             Type Switch

type Retriever interface {
     Get( url string) string
}

type Postser interface {
    Post(url string,
        form map[string] string) string
}

const  url  = "http://www.baidu.com"
func post( postser Postser)  {
    postser.Post(url, map[string] string{
            "name": "yuxiaoba",
            "course": "go",
        })
}

type RetrieverPoster interface {  //接口的组合
    Retriever
    Postser
}

func session( s RetrieverPoster)  string{

    s.Post(url, map[string]string{
        "contents": "another faked baidu.com",
    })
    return s.Get(url)
}
//func download( r Retriever) string {
//    return  r.Get("http://www.baidu.com")
//}

func inspect(r Retriever)  {
    switch v := r.(type) {
    case *mock.Retriever:
        fmt.Println("Contents", v.Contents)

    case *real.Retriever:
        fmt.Println("UserAgent", v.UserAgent)
    }
    fmt.Printf("%T %v
", r, r)
    fmt.Println()
}

func main() {
    var r  Retriever
    retriever := mock.Retriever{"this is a fake baidu"}
    r = &retriever
    inspect(r)  //Contents this is a fake baidu
                //     *mock.Retriever Retriver: {Contents = this is a fake baidu}

    r = &real.Retriever{
        UserAgent: "Mozilla/5.0",
        TimeOut: time.Minute,
    }
    inspect(r)     //UserAgent Mozilla/5.0
                  /*   *real.Retriever &{Mozilla/5.0 1m0s}*/

    //type assertion
    realRetriever := r.(*real.Retriever)

    if mockRetriever , ok := r.(*mock.Retriever); ok {
        fmt.Println(mockRetriever.Contents)
    }else {
        fmt.Println("not mock retriever")   //not mock retriever
    }

    fmt.Println(realRetriever.TimeOut)  //1m0s
    /*    fmt.Println(download(r))*/

    fmt.Println(session(&retriever))  //another faked baidu.com

}

package real

import (
    "time"
    "net/http"
    "net/http/httputil"
)

//真实retriever
type Retriever struct {
    UserAgent string
    TimeOut time.Duration
}

func (r *Retriever) Get(url string) string {    //指针接收者
    resp, err := http.Get(url)
    if err != nil {
        panic(err)
    }
    result, err := httputil.DumpResponse( resp, true)
    resp.Body.Close()

    if err != nil{
        panic(err)
    }
    return  string(result)
}

package mock

import "fmt"

type  Retriever struct {
    Contents string
}

func (r *Retriever) String() string {
    return fmt.Sprintf(
        "Retriver: {Contents = %s}", r.Contents,
    )
}

func (r *Retriever) Post (url string,
    form map[string]string) string {
    r.Contents = form["contents"]
    return  "OK"
}

func (r *Retriever) Get(url string) string  {
    return r.Contents
}