Object Storage Service:Range download (Go SDK V1)

Suppose you have an object that is 1000 bytes. The valid download range is from byte 0 to byte 999. If you specify a range outside this interval, the Range parameter has no effect. The response returns a 200 status code and includes the entire object. The following examples show invalid requests and their responses:

• If you specify Range: bytes=500~2000, the end of the range is outside the valid interval. The entire file is returned, and the HTTP status code is 200.

• If you specify Range: bytes=1000~2000, the start of the range is outside the valid interval. The entire file is returned, and the HTTP status code is 200.

A standard behavior range download adds the x-oss-range-behavior:standard request header to change the download behavior of OSS when an invalid range is specified. Again, suppose you have an object that is 1000 bytes:

• If you specify Range: bytes=500~2000, the end of the range is outside the valid interval. The content from byte 500 to byte 999 is returned, and the HTTP status code is 206.

• If you specify Range: bytes=1000~2000, the start of the range is outside the valid interval. The HTTP status code 416 is returned with the InvalidRange error code.

The following code shows how to perform a standard behavior range download.

package main

import (
	"io"
	"log"
	"strings"

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

func main() {
	// Obtain access credentials from environment variables. Before you run this sample code, make sure that the OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables are set.
	provider, err := oss.NewEnvironmentVariableCredentialsProvider()
	if err != nil {
		log.Fatalf("Error: %v", err)
	}

	// Create an OSSClient instance.
	// Set yourEndpoint to the Endpoint of the bucket. For example, for a bucket in the China (Hangzhou) region, set the Endpoint to https://oss-cn-hangzhou.aliyuncs.com. For other regions, use the actual Endpoint.
	// Set yourRegion to the region where the bucket is located. For example, for a bucket in the China (Hangzhou) region, set the region to cn-hangzhou. For other regions, use the actual region.
	clientOptions := []oss.ClientOption{oss.SetCredentialsProvider(&provider)}
	clientOptions = append(clientOptions, oss.Region("yourRegion"))
	// Set the signature version.
	clientOptions = append(clientOptions, oss.AuthVersion(oss.AuthV4))
	client, err := oss.New("yourEndpoint", "", "", clientOptions...)
	if err != nil {
		log.Fatalf("Error: %v", err)
	}

	// Specify the bucket name.
	bucketName := "yourBucketName"
	bucket, err := client.Bucket(bucketName)
	if err != nil {
		log.Fatalf("Error: %v", err)
	}

	// Upload 1,000 bytes of content.
	strContent := ""
	for i := 0; i < 100; i++ {
		strContent += "abcdefghij"
	}
	log.Printf("content len: %d\n", len(strContent))

	// Upload the string.
	objectName := "yourObjectName"
	err = bucket.PutObject(objectName, strings.NewReader(strContent))
	if err != nil {
		log.Fatalf("Error: %v", err)
	}

	// If you specify Range: bytes=500~2000, the end of the range is outside the valid interval. The content from byte 500 to byte 999 is returned, and the HTTP status code is 206.
	// If you specify Range: bytes=1000~2000, the start of the range is outside the valid interval. The HTTP status code 416 is returned with the InvalidRange error code.
	rangeStart := int64(1000)
	rangeEnd := int64(2000)
	body, err := bucket.GetObject(objectName, oss.Range(rangeStart, rangeEnd), oss.RangeBehavior("standard"))
	if err != nil {
		log.Fatalf("Error: %v", err)
	}
	defer body.Close()

	// Read the data into memory.
	data, err := io.ReadAll(body)
	if err != nil {
		log.Fatalf("Error: %v", err)
	}

	if len(data) != 500 {
		log.Fatalf("read data error, len: %d", len(data))
	}
	log.Printf("data: %s", string(data))
}