Object Storage Service:Progress bar

Usage notes

• In this topic, the public endpoint of the China (Hangzhou) region is used. If you want to access OSS from other Alibaba Cloud services in the same region as OSS, use an internal endpoint. For more information about OSS regions and endpoints, see Regions, endpoints and open ports.

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

• In this topic, an OSSClient instance is created by using an OSS endpoint. If you want to create an OSSClient instance by using custom domain names or Security Token Service (STS), see Initialization.

Examples

The following sample code provides an example on how to display the progress of an object named exampleobject.txt that is being downloaded from a bucket named examplebucket:

package main

import (
	"fmt"
	"os"
	"sync/atomic"

	"github.com/aliyun/aliyun-oss-go-sdk/oss"
)

// Specify the progress bar listener. 
type OssProgressListener struct {
	lastProgress int64
}

// Specify the function that is used to handle progress change events. 
func (listener *OssProgressListener) ProgressChanged(event *oss.ProgressEvent) {
	switch event.EventType {
	case oss.TransferStartedEvent:
		fmt.Printf("Transfer Started, ConsumedBytes: %d, TotalBytes %d.\n",
			event.ConsumedBytes, event.TotalBytes)
	case oss.TransferDataEvent:
		if event.TotalBytes != 0 {
			progress := int64(event.ConsumedBytes * 100 / event.TotalBytes)
			if progress != atomic.LoadInt64(&listener.lastProgress) {
				atomic.StoreInt64(&listener.lastProgress, progress)
				fmt.Printf("\rTransfer Data, ConsumedBytes: %d, TotalBytes %d, %d%%.\n",
					event.ConsumedBytes, event.TotalBytes, progress)
			}
		}
	case oss.TransferCompletedEvent:
		fmt.Printf("\nTransfer Completed, ConsumedBytes: %d, TotalBytes %d.\n",
			event.ConsumedBytes, event.TotalBytes)
	case oss.TransferFailedEvent:
		fmt.Printf("\nTransfer Failed, ConsumedBytes: %d, TotalBytes %d.\n",
			event.ConsumedBytes, event.TotalBytes)
	default:
	}
}

func main() {
	// Obtain access credentials from environment variables. Before you run the sample code, make sure that the OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables are configured. 
	provider, err := oss.NewEnvironmentVariableCredentialsProvider()
	if err != nil {
		fmt.Println("Error:", err)
		os.Exit(-1)
	}
	// Create an OSSClient instance. 
	// Specify the endpoint of the region in which the bucket is located. For example, if the bucket is located in the China (Hangzhou) region, set the endpoint to https://oss-cn-hangzhou.aliyuncs.com. Specify your actual endpoint. 
	// Specify the region in which the bucket is located. For example, if the bucket is located in the China (Hangzhou) region, set the region to cn-hangzhou. Specify the actual region.
	clientOptions := []oss.ClientOption{oss.SetCredentialsProvider(&provider)}
	clientOptions = append(clientOptions, oss.Region("yourRegion"))
	// Specify the version of the signature algorithm.
	clientOptions = append(clientOptions, oss.AuthVersion(oss.AuthV4))
	client, err := oss.New("yourEndpoint", "", "", clientOptions...)
	if err != nil {
		fmt.Println("Error:", err)
		os.Exit(-1)
	}
	// Specify the name of the bucket. 
	bucketName := "examplebucket"
	// Specify the full path of the object. Do not include the bucket name in the full path. 
	objectName := "exampleobject.txt"
	// Specify the full path of the local file in which you want to store the downloaded object. If a file that has the same name already exists in the path, the downloaded object overwrites the file. If no file that has the same name exists in the path, the downloaded object is saved in the path. 
	// If you do not specify a local path for the downloaded object, the downloaded object is saved to the path of the project to which the sample program belongs. 
	localFile := "D:\\localpath\\examplefile.txt"

	// Query the name of the bucket. 
	bucket, err := client.Bucket(bucketName)
	if err != nil {
		fmt.Println("Error:", err)
		os.Exit(-1)
	}

	// Display the progress of the download task. 
	err = bucket.GetObjectToFile(objectName, localFile, oss.Progress(&OssProgressListener{}))
	if err != nil {
		fmt.Println("Error:", err)
		os.Exit(-1)
	}
	fmt.Println("Transfer Completed.")
}