如何解决Go语言中的并发文件下载问题？

package main

import (
    "fmt"
    "io"
    "net/http"
    "os"
)

func downloadFile(url string, filename string, ch chan<- string) {
    resp, err := http.Get(url)
    if err != nil {
        ch <- fmt.Sprintf("Error downloading file from %s: %s", url, err.Error())
        return
    }
    defer resp.Body.Close()

    file, err := os.Create(filename)
    if err != nil {
        ch <- fmt.Sprintf("Error creating file %s: %s", filename, err.Error())
        return
    }
    defer file.Close()

    _, err = io.Copy(file, resp.Body)
    if err != nil {
        ch <- fmt.Sprintf("Error writing file %s: %s", filename, err.Error())
        return
    }

    ch <- fmt.Sprintf("File %s downloaded successfully", filename)
}

func main() {
    urls := []string{"http://example.com/file1.txt", "http://example.com/file2.txt", "http://example.com/file3.txt"}

    ch := make(chan string)

    for _, url := range urls {
        go downloadFile(url, url[17:], ch)
    }

    for i := 0; i < len(urls); i++ {
        result := <-ch
        fmt.Println(result)
    }
}