golang实现的wget

func main() {    // 解析命令行参数    flag.Parse()    // 配置HTTP客户端    client := http.Client{        Transport: &http.Transport{            Proxy:      http.ProxyFromEnvironment,            TLSClientConfig: &tls.Config{InsecureSkipVerify: true},        },    }    // 下载文件    download(&client, *url, *filePath, *isResume)}func download(client *http.Client, url, filePath string, isResume bool) error {    // 检查是否支持断点续传    var startPosition int64 = 0    var err error    if isResume {        if isFileExists(filePath) {            startPosition, err = getFileSize(filePath)        }    }    // 创建HTTP请求    req, err := http.NewRequest("GET", url, nil)    if err != nil {        return err    }    if isResume {        req.Header.Set("Range", fmt.Sprintf("bytes=%d-", startPosition))    }    // 开始下载文件或续传文件    res, err := client.Do(req)    if err != nil {        return err    }    defer res.Body.Close()    f, err := os.OpenFile(filePath, os.O_CREATE|os.O_WRONLY, os.ModePerm)    if err != nil {        return err    }    defer f.Close()    // 如果需要续传，则先将位置定位到起始位置    if isResume {        _, err = f.Seek(startPosition, io.SeekStart)        if err != nil {            return err        }    }    _, err = io.Copy(f, res.Body)    if err != nil {        return err    }    return nil}

golang-wget -url=URL -out=FILE_PATH [-resume=true|false] [-proxy=true|false] [-proxyAddr=PROXY_ADDR] [-debug=true|false]

golang-wget -url=https://golang.org/doc/gopher/pkg.png -out=/tmp/pkg.png

golang-wget -url=https://golang.org/doc/gopher/pkg.png -out=/tmp/pkg.png -resume=true

golang-wget -url=https://golang.org/doc/gopher/pkg.png -out=/tmp/pkg.png -proxy=true -proxyAddr=http://proxyserver:port