改进：增加对Upload part - copy API的支持

API文档：https://cloud.tencent.com/document/product/436/8287

example/object/copyPart.go

@@ -0,0 +1,68 @@
+package main
+
+import (
+	"context"
+	"fmt"
+	"os"
+
+	"net/url"
+
+	"net/http"
+
+	"github.com/tencentyun/cos-go-sdk-v5"
+	"github.com/tencentyun/cos-go-sdk-v5/debug"
+)
+
+func initUpload(c *cos.Client, name string) *cos.InitiateMultipartUploadResult {
+	v, _, err := c.Object.InitiateMultipartUpload(context.Background(), name, nil)
+	if err != nil {
+		panic(err)
+	}
+	fmt.Printf("%#v\n", v)
+	return v
+}
+
+func main() {
+	u, _ := url.Parse("https://test-1253846586.cos.ap-guangzhou.myqcloud.com")
+	b := &cos.BaseURL{BucketURL: u}
+	c := cos.NewClient(b, &http.Client{
+		Transport: &cos.AuthorizationTransport{
+			SecretID:  os.Getenv("COS_SECRETID"),
+			SecretKey: os.Getenv("COS_SECRETKEY"),
+			Transport: &debug.DebugRequestTransport{
+				RequestHeader:  true,
+				RequestBody:    true,
+				ResponseHeader: true,
+				ResponseBody:   true,
+			},
+		},
+	})
+
+	sourceUrl := "test-1253846586.cos.ap-guangzhou.myqcloud.com/source/copy_multi_upload.go"
+	name := "test/test_multi_upload.go"
+	up := initUpload(c, name)
+	uploadID := up.UploadID
+
+	opt := &cos.ObjectCopyPartOptions{}
+	res, _, err := c.Object.CopyPart(
+		context.Background(), name, uploadID, 1, sourceUrl, opt)
+	if err != nil {
+		panic(err)
+	}
+	fmt.Println("ETag:", res.ETag)
+
+	completeOpt := &cos.CompleteMultipartUploadOptions{}
+	completeOpt.Parts = append(completeOpt.Parts, cos.Object{
+		PartNumber: 1,
+		ETag:       res.ETag,
+	})
+	v, resp, err := c.Object.CompleteMultipartUpload(
+		context.Background(), name, uploadID, completeOpt,
+	)
+	if err != nil {
+		panic(err)
+	}
+	fmt.Printf("%s\n", resp.Status)
+	fmt.Printf("%#v\n", v)
+	fmt.Printf("%s\n", v.Location)
+}