Golang下载文件方法全解析

resp, err := http.Get("https://example.com/file.zip")
if err != nil {
    log.Fatal(err)
}
defer resp.Body.Close()

file, err := os.Create("file.zip")
if err != nil {
    log.Fatal(err)
}
defer file.Close()

_, err = io.Copy(file, resp.Body)
if err != nil {
    log.Fatal(err)
}

resp, err := http.Get("https://example.com/file.zip")
if err != nil {
    log.Fatal(err)
}
defer resp.Body.Close()

if resp.StatusCode != http.StatusOK {
    log.Fatalf("下载失败: %v", resp.Status)
}

file, err := os.Create("file.zip")
if err != nil {
    log.Fatal(err)
}
defer file.Close()

_, err = io.Copy(file, resp.Body)
if err != nil {
    log.Fatal(err)
}

file, err := os.OpenFile("file.zip", os.O_RDWR|os.O_CREATE, 0644)
if err != nil {
    log.Fatal(err)
}
defer file.Close()

info, _ := file.Stat()
start := info.Size()

req, err := http.NewRequest("GET", "https://example.com/file.zip", nil)
if err != nil {
    log.Fatal(err)
}

if start > 0 {
    req.Header.Set("Range", fmt.Sprintf("bytes=%d-", start))
}

client := &http.Client{}
resp, err := client.Do(req)
if err != nil {
    log.Fatal(err)
}
defer resp.Body.Close()

if resp.StatusCode == http.StatusPartialContent || resp.StatusCode == http.StatusOK {
    _, err = io.Copy(file, resp.Body)
    if err != nil {
        log.Fatal(err)
    }
} else {
    log.Fatalf("服务器不支持断点续传: %v", resp.Status)
}

type ProgressReader struct {
    io.Reader
    Total   int64
    Current int64
    OnProgress func(current, total int64)
}

func (pr *ProgressReader) Read(p []byte) (n int, err error) {
    n, err = pr.Reader.Read(p)
    pr.Current += int64(n)
    if pr.OnProgress != nil {
        pr.OnProgress(pr.Current, pr.Total)
    }
    return
}

resp, _ := http.Get(url)
defer resp.Body.Close()

totalSize := resp.ContentLength
file, _ := os.Create("file.zip")
defer file.Close()

progressReader := &ProgressReader{
    Reader: resp.Body,
    Total:  totalSize,
    OnProgress: func(current, total int64) {
        fmt.Printf("下载进度: %d/%d (%.2f%%)\n", current, total, float64(current)/float64(total)*100)
    },
}

io.Copy(file, progressReader)