英文:
Trying to use channels in go but data is not properly sent/received into the channel
问题
希望能够快速解析非常多相似的URL（只有一个'id'元素在每个URL中不同），并将响应体转储到一个通道中，稍后主函数将查询该通道并用于构建文本文件。
在getpageCanal()函数内部，响应体似乎没问题，但之后，我不明白为什么通道没有正确加载响应体字符串。
package main
import (
"fmt"
"io/ioutil"
"net/http"
"os"
)
func main() {
initial := "https://www1.medion.de/downloads/index.pl?op=detail&id="
ending := "&type=treiber&lang=uk"
links := []string{}
os.Remove("dump.txt")
dumpFile, _ := os.Create("dump.txt")
c := make(chan string)
for i := 16000; i < 16004; i++ {
links = append(links, initial+fmt.Sprint(i)+ending)
}
fmt.Println(links[0])
for _, link := range links {
//希望将此处变为goroutine，但首先我需要让它正常工作
getpageCanal(c, link)
}
for el := range c {
fmt.Println(el)
n, err := dumpFile.WriteString(el)
if err != nil {
fmt.Println(err)
}
if n == 0 {
fmt.Println("主函数中没有写入任何内容")
}
}
}
func getpageCanal(canal chan string, url string) {
defer close(canal)
page, err := http.Get(url)
if err != nil {
fmt.Println("你搞砸了，小伙子")
}
content, er2 := ioutil.ReadAll(page.Body)
//fmt.Println(content)
if er2 != nil {
fmt.Println(er2)
}
canal <- string(content)
}
<details>
<summary>英文:</summary>
The hope is to quickly parse a very large number of similar URLs (only one 'id' element differs from one to the next) and dump the response body into a channel that will later be queried by the main function and used to build a text file.
Inside the `getpageCanal()` function, the body seems to be ok, but after that, I don't understand why the channel doesn't properly load the body string.
```golang
package main
import (
"fmt"
"io/ioutil"
"net/http"
"os"
)
func main() {
initial := "https://www1.medion.de/downloads/index.pl?op=detail&id="
ending := "&type=treiber&lang=uk"
links := []string{}
os.Remove("dump.txt")
dumpFile, _ := os.Create("dump.txt")
c := make(chan string)
for i := 16000; i < 16004; i++ {
links = append(links, initial+fmt.Sprint(i)+ending)
}
fmt.Println(links[0])
for _, link := range links {
//the hope is to make this a go routine, but first I need to just make it work
getpageCanal(c, link)
}
for el := range c {
fmt.Println(el)
n, err := dumpFile.WriteString(el)
if err != nil {
fmt.Println(err)
}
if n == 0 {
fmt.Println(" nothing written in main")
}
}
}
func getpageCanal(canal chan string, url string) {
defer close(canal)
page, err := http.Get(url)
if err != nil {
fmt.Println("you done fucked up, boy")
}
content, er2 := ioutil.ReadAll(page.Body)
//fmt.Println(content)
if er2 != nil {
fmt.Println(er2)
}
canal <- string(content)
}
</details>
# 答案1
**得分**: 1
根据第一个评论的指示（在每次调用后不关闭通道，并将对工作函数的调用设置为goroutine），我现在将为您提供一个可工作的版本：
```go
package main
import (
"fmt"
"io/ioutil"
"net/http"
"os"
)
func main() {
initial := "https://www1.medion.de/downloads/index.pl?op=detail&id="
ending := "&type=treiber&lang=uk"
links := []string{}
os.Remove("dump.txt")
dumpFile, _ := os.Create("dump.txt")
c := make(chan string)
for i := 16000; i < 16004; i++ {
links = append(links, initial+fmt.Sprint(i)+ending)
}
fmt.Println(links[0])
for _, link := range links {
go getpageCanal(c, link)
}
for el := range c {
fmt.Println(el)
n, err := dumpFile.WriteString(el)
if err != nil {
fmt.Println(err)
}
if n == 0 {
fmt.Println(" nothing written in main")
}
}
}
func getpageCanal(canal chan string, url string) {
//defer close(canal)
page, err := http.Get(url)
if err != nil {
fmt.Println("you done fucked up, boy")
}
content, er2 := ioutil.ReadAll(page.Body)
//fmt.Println(content)
if er2 != nil {
fmt.Println(er2)
}
canal <- string(content)
}
希望对您有所帮助！
英文:
After modifying the code as instructed by the first comments (not closing the channel after each call and making the call to the worker function a go routine) I will now provide you with a working version:
package main
import (
"fmt"
"io/ioutil"
"net/http"
"os"
)
func main() {
initial := "https://www1.medion.de/downloads/index.pl?op=detail&id="
ending := "&type=treiber&lang=uk"
links := []string{}
os.Remove("dump.txt")
dumpFile, _ := os.Create("dump.txt")
c := make(chan string)
for i := 16000; i < 16004; i++ {
links = append(links, initial+fmt.Sprint(i)+ending)
}
fmt.Println(links[0])
for _, link := range links {
go getpageCanal(c, link)
}
for el := range c {
fmt.Println(el)
n, err := dumpFile.WriteString(el)
if err != nil {
fmt.Println(err)
}
if n == 0 {
fmt.Println(" nothing written in main")
}
}
}
func getpageCanal(canal chan string, url string) {
//defer close(canal)
page, err := http.Get(url)
if err != nil {
fmt.Println("you done fucked up, boy")
}
content, er2 := ioutil.ReadAll(page.Body)
//fmt.Println(content)
if er2 != nil {
fmt.Println(er2)
}
canal <- string(content)
}
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