Object Storage Service:オブジェクトが同じ名前のオブジェクトによって上書きされないようにする

次のサンプルコードは、既存のオブジェクトが同じ名前の新しくコピーされたオブジェクトによって上書きされないようにする方法の例を示しています。

package main

import (
	"log"

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

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 {
		log.Fatalf("Failed to create credentials provider: %v", err)
	}

	// 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 {
		log.Fatalf("Failed to create OSS client: %v", err)
	}

	// Specify the name of your bucket. 
	bucketName := "yourBucketName"
	// Specify the full path of the source object. Do not include the bucket name in the full path.
	objectName := "yourObjectName"
	// Specify the full path of the destination object. Do not include the bucket name in the full path.
	destObjectName := "yourDestObjectName"

	// Specify the name of the bucket.
	bucket, err := client.Bucket(bucketName)
	if err != nil {
		log.Fatalf("Failed to get bucket '%s': %v", bucketName, err)
	}

	// Specify whether to overwrite an existing object with the same name. 
	// By default, if you do not specify oss.ForbidOverWrite, an object that has the same name is overwritten. 
	// If you set oss.ForbidOverWrite to false, an object that has the same name is overwritten. 
	// If you set oss.ForbidOverWrite to true, an object that has the same name is not overwritten. If such an object exists, an error is reported. 
	forbidWrite := oss.ForbidOverWrite(true)

	// Create a copy of the object within the bucket.
	_, err = bucket.CopyObject(objectName, destObjectName, forbidWrite)
	if err != nil {
		log.Fatalf("Failed to copy object from '%s' to '%s': %v", objectName, destObjectName, err)
	}

	log.Printf("Successfully copied object from '%s' to '%s'", objectName, destObjectName)
}

次のサンプルコードは、マルチパートアップロードを使用してオブジェクトをアップロードするときに、既存のオブジェクトが同じ名前のオブジェクトによって上書きされないようにする方法の例を示しています。

package main

import (
	"log"
	"os"

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

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 {
		log.Fatalf("Failed to create credentials provider: %v", err)
	}

	// 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 {
		log.Fatalf("Failed to create OSS client: %v", err)
	}

	// Specify the name of the bucket. 
	bucketName := "yourBucketName"
	// Specify the full path of the object. Do not include the bucket name in the full path. 
	objectName := "yourObjectName"
	// Specify the full path of the local file. 
	localFilename := "yourLocalFilename"

	// Specify the name of the bucket.
	bucket, err := client.Bucket(bucketName)
	if err != nil {
		log.Fatalf("Failed to get bucket '%s': %v", bucketName, err)
	}

	// Split the object into multiple chunks.
	chunks, err := oss.SplitFileByPartNum(localFilename, 3)
	if err != nil {
		log.Fatalf("Failed to split file: %v", err)
	}

	// Open the local file.
	fd, err := os.Open(localFilename)
	if err != nil {
		log.Fatalf("Failed to open local file '%s': %v", localFilename, err)
	}
	defer fd.Close()

	// Specify whether to overwrite an existing object with the same name. 
	// By default, if you do not specify oss.ForbidOverWrite, an object that has the same name is overwritten. 
	// If you set oss.ForbidOverWrite to false, an object that has the same name is overwritten. 
	// If you set oss.ForbidOverWrite to true, an object that has the same name is not overwritten. If such an object exists, an error is reported. 
	forbidWrite := oss.ForbidOverWrite(true)

	// Step 1: Initiate a multipart upload task. 
	imur, err := bucket.InitiateMultipartUpload(objectName, forbidWrite)
	if err != nil {
		log.Fatalf("Failed to initiate multipart upload for '%s': %v", objectName, err)
	}

	// Step 2: Upload the parts. 
	var parts []oss.UploadPart
	for _, chunk := range chunks {
		fd.Seek(chunk.Offset, os.SEEK_SET)
		// Call the UploadPart method to upload each part. 
		part, err := bucket.UploadPart(imur, fd, chunk.Size, chunk.Number)
		if err != nil {
			log.Fatalf("Failed to upload part %d of '%s': %v", chunk.Number, objectName, err)
		}
		parts = append(parts, part)
	}

	// Step 3: Complete the multipart upload task. Disable overwrites between objects that have the same names. 
	cmur, err := bucket.CompleteMultipartUpload(imur, parts, forbidWrite)
	if err != nil {
		log.Fatalf("Failed to complete multipart upload for '%s': %v", objectName, err)
	}

	log.Printf("Multipart upload completed successfully for '%s'. cmur: %v", objectName, cmur)
}