go语言学习例子No.17-下载视频用ffmpeg合并

现在还不知道如何爬取视频地址，用插件获取视频地址

在项目里新建1.txt，粘贴进去

go代码部分合并了上面的带进度条下载和执行cmd命令部分

package main

import (
	"bufio"
	"fmt"
	"io"
	"io/ioutil"
	"log"
	"net/http"
	"os"
	"os/exec"
	"strconv"
)

type WriteCounter struct {
	Total uint64
}

func (wc *WriteCounter) Write(p []byte) (int, error) {
	n := len(p)
	wc.Total += uint64(n)
	wc.PrintProgress()
	return n, nil
}

func (wc WriteCounter) PrintProgress() {

	fmt.Printf("\rDownloading... %d complete", wc.Total)
}

func main() {

	s := readfile("./1.txt")
	var filename string
	for i, u := range s {
		filename = strconv.Itoa(i) + ".ts" //int转成string
		writefile("file '" + filename + "'\n")
		DownloadFile(filename, u)
	}
	fmt.Printf("download completed!")
	runcmd()
	delfile()

}

func DownloadFile(filepath string, url string) error {

	out, err := os.Create(filepath)
	if err != nil {
		return err
	}
	defer out.Close()

	// Get the data
	resp, err := http.Get(url)
	if err != nil {
		return err
	}
	defer resp.Body.Close()

	// Create our progress reporter and pass it to be used alongside our writer
	counter := &WriteCounter{}
	_, err = io.Copy(out, io.TeeReader(resp.Body, counter))
	if err != nil {
		return err
	}

	// The progress use the same line so print a new line once it's finished downloading
	fmt.Print("\n")

	return nil
}

func readfile(path string) []string {
	file, err := os.Open(path)
	if err != nil {
		panic(err)
	}
	defer file.Close()
	br := bufio.NewReader(file)
	s := make([]string, 0)
	for {
		a, _, c := br.ReadLine() //按行读取
		if c == io.EOF {
			break
		}
		s = append(s, string(a)) //追加到切片
	}
	return s

}

func writefile(f string) { //创建list.txt文件再写入
	filePath := "list.txt"
	file, err := os.OpenFile(filePath, os.O_WRONLY|os.O_CREATE|os.O_APPEND, 0666)
	if err != nil {
		fmt.Println("open file err", err)
	}
	//及时关闭file句柄
	defer file.Close()

	//写入文件时，使用带缓存的 *Writer
	write := bufio.NewWriter(file)
	write.WriteString(f)
	//Flush将缓存的文件真正写入到文件中
	write.Flush()
}

func runcmd() {
	cmd := exec.Command("cmd.exe", "/c", `C:\ffmpeg\ffmpeg.exe -f concat -safe 0 -i list.txt -c copy output.mp4`)
	err := cmd.Run()//start不等返回就接着执行下面的代码，Run会等待命令执行完在执行后面的
	if err != nil {
		log.Fatal(err)
	}
}
func delfile() {//删除文件
	var s string
	files, _ := ioutil.ReadDir("./")
	for _, f := range files {
		s = f.Name()
		if s[2:] == "ts" {
			os.Remove(f.Name()) //删除文件
		}

	}

}