并发下载网络资源并保存

使用go协程和channel管道实现下载

package main
import (
    "fmt"
    "io/ioutil"
    "net/http"
    "os"
    // "strconv"
    "strings"
)
func download(url string, name string, ret chan<- struct{}) {
    // fmt.Println(name)
    if name == "" {
        names := strings.Split(url, "/")
        name = names[len(names)-1]
    }
    // fmt.Println(name)
    response, err := http.Get(url)
    defer response.Body.Close()
    if err != nil {
        fmt.Println(err)
    }
    body, err := ioutil.ReadAll(response.Body)
    if err != nil {
        fmt.Println(err)
    }
    file, err := os.OpenFile(name, os.O_RDWR|os.O_CREATE, 0666)
    if err != nil {
        fmt.Println(err)
    }
    defer file.Close()
    _, er := file.Write(body)
    if er != nil {
        fmt.Println(er)
    }
    // fmt.Println(string(body))
    // close(ret)
    ret <- struct{}{}
}
func main() {
    urls := []string{"https://gloimg.zafcdn.com/zaful/pdm-product-pic/Clothing/2017/10/23/source-img/20171023104754_59693.png", "https://gloimg.zafcdn.com/zaful/pdm-product-pic/Clothing/2018/05/26/source-img/20180526163835_98732.png"}
    ret := make(chan struct{}, len(urls))
    // fmt.Println(len(urls))
    i := 0
    for _, url := range urls {
        go download(url, "", ret)
        i += 2
    }
    // select {}
    for i := 0; i < len(urls); i++ {
        // fmt.Println(<-ret)
        <-ret
    }
}

result: