Object Storage Service:Downloader no OSS SDK for Go 2.0

O código de exemplo a seguir demonstra como especificar o tamanho e o número de partes baixadas em paralelo configurando os parâmetros em DownloaderOptions:

package main

import (
	"context"
	"flag"
	"log"

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

// Define the global variables.
var (
	region     string // The region in which the bucket is located.
	bucketName string // The name of the bucket.
	objectName string // The name of the object.
)

// Use the init function to initialize 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, "src-object", "", "The name of the source object.")
}

func main() {
	// Parse 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 source object name is empty.
	if len(objectName) == 0 {
		flag.PrintDefaults()
		log.Fatalf("invalid parameters, src object name required")
	}

	// Create an OSS client configuration.
	cfg := oss.LoadDefaultConfig().
		WithCredentialsProvider(credentials.NewEnvironmentVariableCredentialsProvider()).
		WithRegion(region)

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

	// Create a Downloader.
	d := client.NewDownloader()

	// Create a request to download the object.
	request := &oss.GetObjectRequest{
		Bucket: oss.Ptr(bucketName), // The name of the bucket.
		Key:    oss.Ptr(objectName), // The name of the object.
	}

	// The path of the local file.
	localFile := "local-file"

	// Specify downloader options.
	downloaderOptions := func(do *oss.DownloaderOptions) {
		do.PartSize = 20 * 1024 * 1024 // Set the part size to 20 MiB.
		do.ParallelNum = 6            // Set the number of parts that can be downloaded in parallel to 6.
	}

	// Execute the request to download the object.
	result, err := d.DownloadFile(context.TODO(), request, localFile, downloaderOptions)
	if err != nil {
		log.Fatalf("failed to download file %v", err)
	}

	// Print the success response.
	log.Printf("download file %s to local-file successfully, size: %d", objectName, result.Written)
}

O código de exemplo a seguir demonstra como realizar um download resumível configurando DownloaderOptions para um Downloader:

package main

import (
	"context"
	"flag"
	"log"

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

// Define the global variables.
var (
	region     string // The region in which the bucket is located.
	bucketName string // The name of the bucket.
	objectName string // The name of the object.
)

// Use the init function to initialize 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, "src-object", "", "The name of the source object.")
}

func main() {
	// Parse 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 source object name is empty.
	if len(objectName) == 0 {
		flag.PrintDefaults()
		log.Fatalf("invalid parameters, src object name required")
	}

	// Create an OSS client configuration.
	cfg := oss.LoadDefaultConfig().
		WithCredentialsProvider(credentials.NewEnvironmentVariableCredentialsProvider()).
		WithRegion(region)

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

	// Create a Downloader.
	d := client.NewDownloader()

	// Create a request to download the object.
	request := &oss.GetObjectRequest{
		Bucket: oss.Ptr(bucketName), // The name of the bucket.
		Key:    oss.Ptr(objectName), // The name of the object.
	}

	// The path of the local file.
	localFile := "local-file"

	// Specify downloader options.
	downloaderOptions := func(do *oss.DownloaderOptions) {
		do.EnableCheckpoint = true        // Enable checkpoint recording.
		do.CheckpointDir = "./checkpoint" // Specify the path of the checkpoint file.
		do.UseTempFile = true             // Specify the use of a temporary file.
	}

	// Execute the request to download the object.
	result, err := d.DownloadFile(context.TODO(), request, localFile, downloaderOptions)
	if err != nil {
		log.Fatalf("failed to download file %v", err)
	}

	// Print the success response.
	log.Printf("download file %s to local-file successfully, size: %d", objectName, result.Written)
}