goroutine求助

leavesdrift · 2017-11-23 13:53:02 · 992 次点击

新手希望练习 goroutine 爬取资源并且实现超时控制，但下列程序无输出。

package main

import (
    "net/http"
    "io/ioutil"
    "fmt"
    "time"
)

func fetch(ch chan string){
    resp, err := http.Get("http://www.baidu.com")
    defer resp.Body.Close()

    if err != nil {
        panic(err)
    }

    body, err := ioutil.ReadAll(resp.Body)
    ch <-string(body)
}

func main(){
    ch := make(chan string)
    go fetch(ch)

    select {
        case <-ch:
            fmt.Printf("success\n\t->%s", <-ch)
        case <-time.After(3*time.Second):
            fmt.Printf("failed\n\t->nil")
    } 
}

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leavesdrift

@channel

package main

import (
    "net/http"
    "io/ioutil"
    "fmt"
    "time"
)

func fetch(ch chan string){
    resp, err := http.Get("http://www.baidu.com")
    defer resp.Body.Close()

    if err != nil {
        panic(err)
    }

    body, err := ioutil.ReadAll(resp.Body)
    ch <-string(body)
}

func main(){
    ch := make(chan string)
    go fetch(ch)

    select {
        case rs := <-ch:
            fmt.Printf("success\n\t->%s", rs)
        case <-time.After(3*time.Second):
            fmt.Printf("failed\n\t->nil")
    } 
}