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Qiniu MultiRange Download Example
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| package main | |
| import ( | |
| "bytes" | |
| "errors" | |
| "fmt" | |
| "io" | |
| "mime" | |
| "mime/multipart" | |
| "net/http" | |
| "os" | |
| "strings" | |
| ) | |
| // 注意：保证 Ranges 至少有两对，且 Ranges 最终不会覆盖整个文件 | |
| func MultiRangeGet(client *http.Client, url string, ranges [][2]int) ([]byte, error) { | |
| rangeHeaderValue := fmt.Sprintf("bytes=%s", generateRangeHeader(ranges)) | |
| buffer := bytes.NewBuffer(make([]byte, 0, sumRangeSize(ranges))) | |
| req, err := http.NewRequest("GET", url, http.NoBody) | |
| if err != nil { | |
| return nil, err | |
| } | |
| req.Header.Add("Range", rangeHeaderValue) | |
| resp, err := client.Do(req) | |
| if err != nil { | |
| return nil, err | |
| } | |
| defer resp.Body.Close() | |
| switch resp.StatusCode { | |
| case http.StatusOK: | |
| return nil, errors.New("Status code is 200, we don't support it here") | |
| case http.StatusPartialContent: | |
| contentType := resp.Header.Get("Content-Type") | |
| _, params, err := mime.ParseMediaType(contentType) | |
| if err != nil { | |
| return nil, err | |
| } | |
| multipartReader := multipart.NewReader(resp.Body, params["boundary"]) | |
| for { | |
| part, err := multipartReader.NextPart() | |
| if err == io.EOF { | |
| break | |
| } | |
| if err != nil { | |
| return nil, err | |
| } | |
| _, partSize, err := parseContentRange(part.Header.Get("Content-Range")) | |
| if err != nil { | |
| return nil, err | |
| } | |
| copied, err := io.Copy(buffer, part) | |
| if err != nil { | |
| return nil, err | |
| } | |
| if copied != int64(partSize) { | |
| return nil, io.ErrUnexpectedEOF | |
| } | |
| } | |
| default: | |
| return nil, errors.New("Status code is neither 200 nor 206") | |
| } | |
| return buffer.Bytes(), nil | |
| } | |
| func generateRangeHeader(ranges [][2]int) string { | |
| parts := make([]string, 0, len(ranges)) | |
| for _, rg := range ranges { | |
| parts = append(parts, fmt.Sprintf("%d-%d", rg[0], rg[0]+rg[1]-1)) | |
| } | |
| return strings.Join(parts, ",") | |
| } | |
| func sumRangeSize(ranges [][2]int) int { | |
| sum := 0 | |
| for _, rg := range ranges { | |
| sum += rg[1] | |
| } | |
| return sum | |
| } | |
| func parseContentRange(contentRange string) (int, int, error) { | |
| var from, to, total int | |
| parsed, err := fmt.Sscanf(contentRange, "bytes %d-%d/%d", &from, &to, &total) | |
| if err != nil || parsed != 3 { | |
| return 0, 0, fmt.Errorf("Content-Range is invalid: %s", err) | |
| } | |
| return from, to - from + 1, nil | |
| } |
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