Download objects - Object Storage Service - Alibaba Cloud Documentation Center

By default, when you call the GetObject operation on an object in a versioning-enabled bucket, only the current version of the object is returned.

Background information

When you call the GetObject operation to download an object in a bucket, you may obtain one of the following results:

If the current version of the object is a delete marker, OSS returns 404 Not Found.
If a version ID of the object is specified in the request, OSS returns the specified version of the object. If the version ID is set to null in the request, OSS returns the version whose version ID is null.
If the version ID specified in the request is the version ID of a delete marker, OSS returns 405 Method Not Allowed.

Usage notes

In this topic, the public endpoint of the China (Hangzhou) region is used. If you want to access OSS by using other Alibaba Cloud services in the same region as OSS, use an internal endpoint. For more information about the regions and endpoints supported by OSS, see Regions and endpoints.
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 Create an OSSClient instance.
To download an object, you must have the oss:GetObject permission. For more information, see Attach a custom policy to a RAM user.

Sample code

The following sample code provides an example on how to download an object:

#include <alibabacloud/oss/OssClient.h>
using namespace AlibabaCloud::OSS;

int main(void)
{
    /* Initialize information about the account that is used to access OSS. */
            
    /* 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. */
    std::string Endpoint = "yourEndpoint";
    /* Specify the name of the bucket. Example: examplebucket. */
    std::string BucketName = "examplebucket";
    /* Specify the full path of the object. Do not include the bucket name in the full path. Example: exampledir/exampleobject.txt. */
    std::string ObjectName = "exampledir/exampleobject.txt";

    /* Initialize resources such as network resources. */
    InitializeSdk();

    ClientConfiguration conf;
    /* 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. */
    auto credentialsProvider = std::make_shared<EnvironmentVariableCredentialsProvider>();
    OssClient client(Endpoint, credentialsProvider, conf);

    /* Download the object into memory. */
    GetObjectRequest request(BucketName, ObjectName);
    request.setVersionId("yourObjectVersionId");
    auto outcome = client.GetObject(request);
    if (outcome.isSuccess()) {
        std::cout << "getObjectToBuffer" << " success, Content-Length:" << outcome.result().Metadata().ContentLength() << std::endl;
        /* Read the content of the downloaded object. */
        std::string content;
        *(outcome.result().Content()) >> content;
        std::cout << "getObjectToBuffer" << "content:" << content << std::endl;
        /* Display the version ID of the downloaded object. */
        std::cout << "versionid:" << outcome.result().VersionId() << std::endl;
    }
    else {
            /* Handle exceptions. */
            std::cout << "getObjectToBuffer fail" <<
        ",code:" << outcome.error().Code() <<
        ",message:" << outcome.error().Message() <<
        ",requestId:" << outcome.error().RequestId() << std::endl;
        return -1;
    }

    /* Release resources such as network resources. */
    ShutdownSdk();
    return 0;
}

References

For more information about the API operation that you can call to download an object, see GetObject.