Range download with OSS SDK for Go 2.0

Usage notes

• The sample code uses the China (Hangzhou) region ID cn-hangzhou and a public endpoint. To access OSS from other Alibaba Cloud services in the same region, use an internal endpoint. For more information about supported regions and endpoints, see Regions and Endpoints.

• In this topic, access credentials are obtained from environment variables. For more information, 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 policies 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 adds the RangeBehavior:standard request header to download a specified byte range with 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 complete sample code, see the GitHub example.

• For the API reference, see GetObject.