Object Storage Service:Range download (Go SDK V2)

Usage notes

• The sample code in this topic uses the China (Hangzhou) region ID, cn-hangzhou. By default, a public endpoint is used. If you want to access OSS from other Alibaba Cloud products in the same region, use an internal endpoint. For more information about the regions and endpoints that OSS supports, see Regions and endpoints.

• In this topic, access credentials are read from environment variables. For more information about how to configure access credentials, see Configure access credentials.

Permissions

By default, an Alibaba Cloud account has full permissions. RAM users or RAM roles under an Alibaba Cloud account do not have any permissions by default. The Alibaba Cloud account or account administrator must grant operation permissions through RAM Policy or Bucket Policy.

Method definition

func (c *Client) GetObject(ctx context.Context, request *GetObjectRequest, optFns ...func(*Options)) (*GetObjectResult, error)

Request parameters

Return values

Sample code

The following sample code shows how to add the RangeBehavior:standard request header to download data from a specified range of a file using the standard download behavior.

package main

import (
	"context"
	"flag"
	"io"
	"log"

	"github.com/aliyun/alibabacloud-oss-go-sdk-v2/oss"
	"github.com/aliyun/alibabacloud-oss-go-sdk-v2/oss/credentials"
)

// Define global variables.
var (
	region     string // The region.
	bucketName string // The bucket name.
	objectName string // The object name.
)

// The init function is used to initialize command-line parameters.
func init() {
	flag.StringVar(&region, "region", "", "The region in which the bucket is located.")
	flag.StringVar(&bucketName, "bucket", "", "The name of the bucket.")
	flag.StringVar(&objectName, "object", "", "The name of the object.")
}

func main() {
	// Parse command-line parameters.
	flag.Parse()

	// Check whether the bucket name is empty.
	if len(bucketName) == 0 {
		flag.PrintDefaults()
		log.Fatalf("invalid parameters, bucket name required")
	}

	// Check whether the region is empty.
	if len(region) == 0 {
		flag.PrintDefaults()
		log.Fatalf("invalid parameters, region required")
	}

	// Check whether the object name is empty.
	if len(objectName) == 0 {
		flag.PrintDefaults()
		log.Fatalf("invalid parameters, object name required")
	}

	// Load the default configurations and set the credential provider and region.
	cfg := oss.LoadDefaultConfig().
		WithCredentialsProvider(credentials.NewEnvironmentVariableCredentialsProvider()).
		WithRegion(region)

	// Create an OSS client.
	client := oss.NewClient(cfg)

	// Create a request to get the object.
	request := &oss.GetObjectRequest{
		Bucket:        oss.Ptr(bucketName),     // The bucket name.
		Key:           oss.Ptr(objectName),     // The object name.
		Range:         oss.Ptr("bytes=15-35"), // Specify the download range.
		RangeBehavior: oss.Ptr("standard"),     // Specify the standard range download behavior.
	}

	// Execute the operation to get the object and process the result.
	result, err := client.GetObject(context.TODO(), request)
	if err != nil {
		log.Fatalf("failed to get object %v", err)
	}
	defer result.Body.Close() // Make sure that the response body is closed when the function ends.

	log.Printf("get object result:%#v\n", result)

	// Read the content of the object.
	data, _ := io.ReadAll(result.Body)
	log.Printf("body:%s\n", data)
}

References

• For the complete sample code for range download, see the GitHub example.

• For more information about the API operation for range download, see GetObject.