5-2 接口的定义和实现

main.go

package main

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

type Retriever interface {
    Get(url string) string
}

func download(r Retriever) string {
    return r.Get("http://www.imooc.com")
}

func main() {
    var r Retriever
    r = &mock.Retriever{Contents:"this is a fake imooc.com"}
    r = &real.RealRetriever{}
    fmt.Println(download(r))
}

mock/mockretriever.go

package mock

type Retriever struct {
    Contents string
}

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

real/retriever.go

package real

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

type RealRetriever struct {
    UserAgent string
    TimeOut time.Duration
}

func (r *RealRetriever) Get(url string) string {
    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)
}