Object Storage Service:Resumable download

import com.aliyun.oss.ClientBuilderConfiguration;
import com.aliyun.oss.OSS;
import com.aliyun.oss.common.auth.*;
import com.aliyun.oss.OSSClientBuilder;
import com.aliyun.oss.OSSException;
import com.aliyun.oss.common.comm.SignVersion;
import com.aliyun.oss.model.*;

public class Demo {
    public static void main(String[] args) throws Exception {
        // In this example, the endpoint of the China (Hangzhou) region is used. Specify your actual endpoint. 
        String endpoint = "https://oss-cn-hangzhou.aliyuncs.com";
        // 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. 
        EnvironmentVariableCredentialsProvider credentialsProvider = CredentialsProviderFactory.newEnvironmentVariableCredentialsProvider();
        // Specify the name of the bucket. Example: examplebucket. 
        String bucketName = "examplebucket";
        // Specify the full path of the object. Example: exampledir/exampleobject.txt. Do not include the bucket name in the full path. 
        String objectName = "exampledir/exampleobject.txt";
        // 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.
        String region = "cn-hangzhou";

        // Create an OSSClient instance. 
        // Call the shutdown method to release associated resources when the OSSClient is no longer in use.
        ClientBuilderConfiguration clientBuilderConfiguration = new ClientBuilderConfiguration();
        clientBuilderConfiguration.setSignatureVersion(SignVersion.V4);        
        OSS ossClient = OSSClientBuilder.create()
        .endpoint(endpoint)
        .credentialsProvider(credentialsProvider)
        .clientConfiguration(clientBuilderConfiguration)
        .region(region)               
        .build();
        
      	try {
            // Perform resumable download in which 10 parts can be concurrently downloaded. 
            DownloadFileRequest downloadFileRequest = new DownloadFileRequest(bucketName, objectName);
            // Specify the full path to which you want to download the object. Example: D:\\localpath\\examplefile.txt. 
            downloadFileRequest.setDownloadFile("D:\\localpath\\examplefile.txt");
            // Specify the part size. Unit: bytes. Valid values: 100 KB to 5 GB. The default part size is 100 KB. 
            downloadFileRequest.setPartSize(1 * 1024 * 1024);
            // Specify the number of concurrent threads for the resumable download task. Default value: 1. 
            downloadFileRequest.setTaskNum(10);
            // Specify whether to enable resumable download. By default, resumable download is disabled. 
            downloadFileRequest.setEnableCheckpoint(true);
            // Specify the full path of the checkpoint file. Example: D:\\localpath\\examplefile.txt.dcp. 
            // The checkpoint file is generated when the download is interrupted. If you want to resume the download task, you must specify the full path of the checkpoint file. After the object is downloaded, the checkpoint file is deleted. 
            //downloadFileRequest.setCheckpointFile("D:\\localpath\\examplefile.txt.dcp");

            // Download the object. 
            DownloadFileResult downloadRes = ossClient.downloadFile(downloadFileRequest);
            // After the object is downloaded, the object metadata is returned. 
            ObjectMetadata objectMetadata = downloadRes.getObjectMetadata();
            System.out.println(objectMetadata.getETag());
            System.out.println(objectMetadata.getLastModified());
            System.out.println(objectMetadata.getUserMetadata().get("meta"));
        } catch (OSSException oe) {
            System.out.println("Caught an OSSException, which means your request made it to OSS, "
                    + "but was rejected with an error response for some reason.");
            System.out.println("Error Message:" + oe.getErrorMessage());
            System.out.println("Error Code:" + oe.getErrorCode());
            System.out.println("Request ID:" + oe.getRequestId());
            System.out.println("Host ID:" + oe.getHostId());
        } catch (Throwable ce) {
            System.out.println("Caught an ClientException, which means the client encountered "
                    + "a serious internal problem while trying to communicate with OSS, "
                    + "such as not being able to access the network.");
            System.out.println("Error Message:" + ce.getMessage());
        } finally {
            if (ossClient != null) {
                ossClient.shutdown();
            }
        }
    }
}

import argparse
import alibabacloud_oss_v2 as oss

# Create a parser for parsing command-line arguments and describe the purpose of the script.
parser = argparse.ArgumentParser(description="download file sample")

# Specify the --region parameter to indicate the region in which the bucket is located. This parameter is required.
parser.add_argument('--region', help='The region in which the bucket is located.', required=True)
# Specify the --bucket parameter to indicate the name of the bucket in which the object is stored. This parameter is required.
parser.add_argument('--bucket', help='The name of the bucket.', required=True)
# Specify the --endpoint parameter to indicate the endpoint of the region in which the bucket is located. This parameter is optional.
parser.add_argument('--endpoint', help='The domain names that other services can use to access OSS')
# Specify the --key parameter to indicate the name of the object. This parameter is required.
parser.add_argument('--key', help='The name of the object.', required=True)
# Specify the --file_path parameter to indicate the path to which the object is downloaded. This parameter is required. Example: "/Users/yourLocalPath/yourFileName"
parser.add_argument('--file_path', help='The path to save the downloaded file.', required=True)

def main():
    # Parse the command-line arguments.
    args = parser.parse_args()

    # Obtain access credentials from environment variables for authentication.
    credentials_provider = oss.credentials.EnvironmentVariableCredentialsProvider()

    # Use the default configuration to create a cfg object and specify the credential provider.
    cfg = oss.config.load_default()
    cfg.credentials_provider = credentials_provider
    
    # Set the region attribute of the cfg object to the region provided in the command line.
    cfg.region = args.region

    # If a custom endpoint is provided, update the endpoint attribute of the cfg object with the provided endpoint.
    if args.endpoint is not None:
        cfg.endpoint = args.endpoint

    # Use the preceding settings to initialize the OSSClient instance.
    client = oss.Client(cfg)

    # Create a downloader and specify advanced options.
    downloader = client.downloader(
        use_temp_file=True,            # Use a temporary file.
        enable_checkpoint=True,        # Enable resumable download.
        checkpoint_dir=args.file_path, # Specify the directory where the checkpoint file is saved.
        verify_data=True # Specify data verification.
    )

    # Call the download_file method to download the object.
    result = downloader.download_file(
        oss.GetObjectRequest(
            bucket=args.bucket,  # Specify the bucket name.
            key=args.key,        # Specify the name of the object to be downloaded.
        ),
        filepath=args.file_path  # Specify the local file path to which the object is downloaded.
    )

    # Display the result, including the number of written bytes.
    print(f'written: {result.written}')

# Call the main function to start the processing logic when the script is directly run.
if __name__ == "__main__":
    main()  # Specify the entry point of the script. The control flow starts here.

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)
}

using Aliyun.OSS;
using Aliyun.OSS.Common;

// 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. 
var endpoint = "yourEndpoint";
// 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. 
var accessKeyId = Environment.GetEnvironmentVariable("OSS_ACCESS_KEY_ID");
var accessKeySecret = Environment.GetEnvironmentVariable("OSS_ACCESS_KEY_SECRET");
// Specify the name of the bucket. Example: examplebucket. 
var bucketName = "examplebucket";
// Specify the full path of the object. Do not include the bucket name in the full path. Example: exampledir/exampleobject.txt. 
var objectName = "exampleobject.txt";
// Download the object to D:\\localpath. After the object is downloaded, the local file is named examplefile.txt. If a file with the same name already exists, the downloaded object overwrites the file. Otherwise, the downloaded object is saved in the path. 
// If you do not specify a path for the downloaded object, the downloaded object is saved to the path of the project to which the sample program belongs. 
var downloadFilename = "D:\\localpath\\examplefile.txt";
// Specify the full path of the checkpoint file. Example: D:\\localpath\\examplefile.txt.dcp. 
// The checkpoint file is generated when the download is interrupted. If you want to resume the download task, you must specify the full path of the checkpoint file. After the object is downloaded, the checkpoint file is deleted. 
var checkpointDir = "D:\\localpath\\examplefile.txt.dcp";
// 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.
const string region = "cn-hangzhou";

// Create a ClientConfiguration instance and modify the default parameters based on your requirements.
var conf = new ClientConfiguration();

// Use the signature algorithm V4.
conf.SignatureVersion = SignatureVersion.V4;

// Create an OSSClient instance.
var client = new OssClient(endpoint, accessKeyId, accessKeySecret, conf);
client.SetRegion(region);
try
{
    // Configure multiple parameters by using DownloadObjectRequest. 
    DownloadObjectRequest request = new DownloadObjectRequest(bucketName, objectName, downloadFilename)
    {
        // Specify the size of each part to download. Unit: bytes. 
        PartSize = 8 * 1024 * 1024,
        // Specify the number of concurrent threads. 
        ParallelThreadCount = 3,
        // checkpointDir is a file used to store the information about the resumable download progress. If a part fails to be downloaded, you can resume the download task based on the progress that is recorded in the checkpointDir file. If you set checkpointDir to null, resumable download does not take effect and the object is downloaded again if it fails to be downloaded. 
        CheckpointDir = checkpointDir,
    };
    // Start the resumable download. 
    client.ResumableDownloadObject(request);
    Console.WriteLine("Resumable download object:{0} succeeded", objectName);
}
catch (OssException ex)
{
    Console.WriteLine("Failed with error code: {0}; Error info: {1}. \nRequestID:{2}\tHostID:{3}",
        ex.ErrorCode, ex.Message, ex.RequestId, ex.HostId);
}
catch (Exception ex)
{
    Console.WriteLine("Failed with error info: {0}", ex.Message);
}

#import "DownloadService.h"
#import "OSSTestMacros.h"

@implementation DownloadRequest

@end

@implementation Checkpoint

- (instancetype)copyWithZone:(NSZone *)zone {
    Checkpoint *other = [[[self class] allocWithZone:zone] init];

    other.etag = self.etag;
    other.totalExpectedLength = self.totalExpectedLength;

    return other;
}

@end


@interface DownloadService()<NSURLSessionTaskDelegate, NSURLSessionDataDelegate>

@property (nonatomic, strong) NSURLSession *session;         // The network session. 
@property (nonatomic, strong) NSURLSessionDataTask *dataTask;   // The data request task. 
@property (nonatomic, copy) DownloadFailureBlock failure;    // The request failure. 
@property (nonatomic, copy) DownloadSuccessBlock success;    // The request success. 
@property (nonatomic, copy) DownloadProgressBlock progress;  // The download progress. 
@property (nonatomic, copy) Checkpoint *checkpoint;        // The checkpoint. 
@property (nonatomic, copy) NSString *requestURLString;    // The object resource URL used in a download request. 
@property (nonatomic, copy) NSString *headURLString;       // The object resource URL used in a HEAD request. 
@property (nonatomic, copy) NSString *targetPath;     // The path to which the object is stored. 
@property (nonatomic, assign) unsigned long long totalReceivedContentLength; // The size of the downloaded content. 
@property (nonatomic, strong) dispatch_semaphore_t semaphore;

@end

@implementation DownloadService

- (instancetype)init
{
    self = [super init];
    if (self) {
        NSURLSessionConfiguration *conf = [NSURLSessionConfiguration defaultSessionConfiguration];
        conf.timeoutIntervalForRequest = 15;

        NSOperationQueue *processQueue = [NSOperationQueue new];
        _session = [NSURLSession sessionWithConfiguration:conf delegate:self delegateQueue:processQueue];
        _semaphore = dispatch_semaphore_create(0);
        _checkpoint = [[Checkpoint alloc] init];
    }
    return self;
}
// DownloadRequest is the core of the download logic. 
+ (instancetype)downloadServiceWithRequest:(DownloadRequest *)request {
    DownloadService *service = [[DownloadService alloc] init];
    if (service) {
        service.failure = request.failure;
        service.success = request.success;
        service.requestURLString = request.sourceURLString;
        service.headURLString = request.headURLString;
        service.targetPath = request.downloadFilePath;
        service.progress = request.downloadProgress;
        if (request.checkpoint) {
            service.checkpoint = request.checkpoint;
        }
    }
    return service;
}

/**
 * Obtain object information by using the HEAD method. OSS compares the ETag of the object with the ETag stored in the local checkpoint file and returns the comparison result. 
 */
- (BOOL)getFileInfo {
    __block BOOL resumable = NO;
    NSURL *url = [NSURL URLWithString:self.headURLString];
    NSMutableURLRequest *request = [[NSMutableURLRequest alloc]initWithURL:url];
    [request setHTTPMethod:@"HEAD"];
    // Process the information about the object. For example, the ETag is used for precheck during resumable upload, and the Content-Length header is used to calculate the download progress. 
    NSURLSessionDataTask *task = [[NSURLSession sharedSession] dataTaskWithRequest:request completionHandler:^(NSData * _Nullable data, NSURLResponse * _Nullable response, NSError * _Nullable error) {
        if (error) {
            NSLog(@"Failed to obtain object metadata. error: %@", error);
        } else {
            NSHTTPURLResponse *httpResponse = (NSHTTPURLResponse *)response;
            NSString *etag = [httpResponse.allHeaderFields objectForKey:@"Etag"];
            if ([self.checkpoint.etag isEqualToString:etag]) {
                resumable = YES;
            } else {
                resumable = NO;
            }
        }
        dispatch_semaphore_signal(self.semaphore);
    }];
    [task resume];

    dispatch_semaphore_wait(self.semaphore, DISPATCH_TIME_FOREVER);
    return resumable;
}

/**
 * Query the size of the local file. 
 */
- (unsigned long long)fileSizeAtPath:(NSString *)filePath {
    unsigned long long fileSize = 0;
    NSFileManager *dfm = [NSFileManager defaultManager];
    if ([dfm fileExistsAtPath:filePath]) {
        NSError *error = nil;
        NSDictionary *attributes = [dfm attributesOfItemAtPath:filePath error:&error];
        if (!error && attributes) {
            fileSize = attributes.fileSize;
        } else if (error) {
            NSLog(@"error: %@", error);
        }
    }

    return fileSize;
}

- (void)resume {
    NSURL *url = [NSURL URLWithString:self.requestURLString];
    NSMutableURLRequest *request = [[NSMutableURLRequest alloc]initWithURL:url];
    [request setHTTPMethod:@"GET"];

    BOOL resumable = [self getFileInfo];    // If the value of the resumable field is NO, the resumable download condition is not met. 
    if (resumable) {
        self.totalReceivedContentLength = [self fileSizeAtPath:self.targetPath];
        NSString *requestRange = [NSString stringWithFormat:@"bytes=%llu-", self.totalReceivedContentLength];
        [request setValue:requestRange forHTTPHeaderField:@"Range"];
    } else {
        self.totalReceivedContentLength = 0;
    }

    if (self.totalReceivedContentLength == 0) {
        [[NSFileManager defaultManager] createFileAtPath:self.targetPath contents:nil attributes:nil];
    }

    self.dataTask = [self.session dataTaskWithRequest:request];
    [self.dataTask resume];
}

- (void)pause {
    [self.dataTask cancel];
    self.dataTask = nil;
}

- (void)cancel {
    [self.dataTask cancel];
    self.dataTask = nil;
    [self removeFileAtPath: self.targetPath];
}

- (void)removeFileAtPath:(NSString *)filePath {
    NSError *error = nil;
    [[NSFileManager defaultManager] removeItemAtPath:self.targetPath error:&error];
    if (error) {
        NSLog(@"remove file with error : %@", error);
    }
}

#pragma mark - NSURLSessionDataDelegate

- (void)URLSession:(NSURLSession *)session task:(NSURLSessionTask *)task
// Check whether the download task is complete and return the result to the upper layer. 
didCompleteWithError:(nullable NSError *)error {
    NSHTTPURLResponse *httpResponse = (NSHTTPURLResponse *)task.response;
    if ([httpResponse isKindOfClass:[NSHTTPURLResponse class]]) {
        if (httpResponse.statusCode == 200) {
            self.checkpoint.etag = [[httpResponse allHeaderFields] objectForKey:@"Etag"];
            self.checkpoint.totalExpectedLength = httpResponse.expectedContentLength;
        } else if (httpResponse.statusCode == 206) {
            self.checkpoint.etag = [[httpResponse allHeaderFields] objectForKey:@"Etag"];
            self.checkpoint.totalExpectedLength = self.totalReceivedContentLength + httpResponse.expectedContentLength;
        }
    }

    if (error) {
        if (self.failure) {
            NSMutableDictionary *userInfo = [NSMutableDictionary dictionaryWithDictionary:error.userInfo];
            [userInfo oss_setObject:self.checkpoint forKey:@"checkpoint"];

            NSError *tError = [NSError errorWithDomain:error.domain code:error.code userInfo:userInfo];
            self.failure(tError);
        }
    } else if (self.success) {
        self.success(@{@"status": @"success"});
    }
}

- (void)URLSession:(NSURLSession *)session dataTask:(NSURLSessionDataTask *)dataTask didReceiveResponse:(NSURLResponse *)response completionHandler:(void (^)(NSURLSessionResponseDisposition))completionHandler
{
    NSHTTPURLResponse *httpResponse = (NSHTTPURLResponse *)dataTask.response;
    if ([httpResponse isKindOfClass:[NSHTTPURLResponse class]]) {
        if (httpResponse.statusCode == 200) {
            self.checkpoint.totalExpectedLength = httpResponse.expectedContentLength;
        } else if (httpResponse.statusCode == 206) {
            self.checkpoint.totalExpectedLength = self.totalReceivedContentLength +  httpResponse.expectedContentLength;
        }
    }

    completionHandler(NSURLSessionResponseAllow);
}
// Write the received network data to the object by using append upload and update the download progress. 
- (void)URLSession:(NSURLSession *)session dataTask:(NSURLSessionDataTask *)dataTask didReceiveData:(NSData *)data {

    NSFileHandle *fileHandle = [NSFileHandle fileHandleForWritingAtPath:self.targetPath];
    [fileHandle seekToEndOfFile];
    [fileHandle writeData:data];
    [fileHandle closeFile];

    self.totalReceivedContentLength += data.length;
    if (self.progress) {
        self.progress(data.length, self.totalReceivedContentLength, self.checkpoint.totalExpectedLength);
    }
}

@end

#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 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. */
    std::string Region = "yourRegion";
    /* 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";
    /* Download the object to the local path D:\\localpath as a local file named examplefile.txt. If a file that has the same name already exists in the specified path, the downloaded object overwrites the file. Otherwise, the downloaded object is saved in the path. */
    /* If you do not specify the path of the local file, the downloaded object is saved to the path of the project to which the sample program belongs. */
    std::string DownloadFilePath = "D:\\localpath\\examplefile.txt";
    /* Specify the directory where the checkpoint file is stored and make sure that the specified directory exists, such as D:\\localpath. */
    /* The checkpoint file is generated when the download is interrupted. If you want to resume the download task, you must specify the full path of the checkpoint file. After the object is downloaded, the checkpoint file is deleted. */
    std::string CheckpointFilePath = "D:\\localpath";

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

    ClientConfiguration conf;
    conf.signatureVersion = SignatureVersionType::V4;
    /* 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);
    client.SetRegion(Region);

    /* Start resumable download. */
    DownloadObjectRequest request(BucketName, ObjectName, DownloadFilePath, CheckpointFilePath);
    auto outcome = client.ResumableDownloadObject(request);

    if (!outcome.isSuccess()) {
        /* Handle exceptions. */
        std::cout << "ResumableDownloadObject 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;
}

#include "oss_api.h"
#include "aos_http_io.h"
/* 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. */
const char *endpoint = "yourEndpoint";

/* Specify the name of the bucket. Example: examplebucket. */
const char *bucket_name = "examplebucket";
/* Specify the full path of the object. Do not include the bucket name in the full path. Example: exampledir/exampleobject.txt. */
const char *object_name = "exampledir/exampleobject.txt";
/* Specify the full path of the local file. */
const char *local_filename = "yourLocalFilename";
/* 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. */
const char *region = "yourRegion";
void init_options(oss_request_options_t *options)
{
    options->config = oss_config_create(options->pool);
    /* Use a char* string to initialize aos_string_t. */
    aos_str_set(&options->config->endpoint, endpoint);
    /* 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. */    
    aos_str_set(&options->config->access_key_id, getenv("OSS_ACCESS_KEY_ID"));
    aos_str_set(&options->config->access_key_secret, getenv("OSS_ACCESS_KEY_SECRET"));
    // Specify two additional parameters.
    aos_str_set(&options->config->region, region);
    options->config->signature_version = 4;
    /* Specify whether to use CNAME. The value 0 indicates that CNAME is not used. */
    options->config->is_cname = 0;
    /* Specify network parameters, such as the timeout period. */
    options->ctl = aos_http_controller_create(options->pool, 0);
}
int main(int argc, char *argv[])
{
    /* Call the aos_http_io_initialize method in main() to initialize global resources, such as network and memory resources. */
    if (aos_http_io_initialize(NULL, 0) != AOSE_OK) {
        exit(1);
    }
    /* Create a memory pool to manage memory. aos_pool_t is equivalent to apr_pool_t. The code that is used to create a memory pool is included in the APR library. */
    aos_pool_t *pool;
    /* Create a memory pool. The value of the second parameter is NULL. This value specifies that the pool does not inherit other memory pools. */
    aos_pool_create(&pool, NULL);
    /* Create and initialize options. This parameter includes global configuration information, such as endpoint, access_key_id, access_key_secret, is_cname, and curl. */
    oss_request_options_t *oss_client_options;
    /* Allocate memory resources in the memory pool to the options. */
    oss_client_options = oss_request_options_create(pool);
    /* Initialize oss_client_options. */
    init_options(oss_client_options);
    /* Initialize the parameters. */
    aos_string_t bucket;
    aos_string_t object;
    aos_string_t file;
    aos_table_t *headers = NULL;
    aos_table_t *resp_headers = NULL; 
    aos_status_t *resp_status = NULL; 
    oss_resumable_clt_params_t *clt_params;
    aos_str_set(&bucket, bucket_name);
    aos_str_set(&object, object_name);
    aos_str_set(&file, local_filename);
    /* Perform resumable download to download the object. */
    clt_params = oss_create_resumable_clt_params_content(pool, 1024 * 100, 3, AOS_TRUE, NULL);
    resp_status = oss_resumable_download_file(oss_client_options, &bucket, &object, &file, headers, NULL, clt_params, NULL, &resp_headers);
    if (aos_status_is_ok(resp_status)) {
        printf("download succeeded\n");
    } else {
        printf("download failed\n");
    }
    /* Release the memory pool. This operation releases memory resources allocated for the request. */
    aos_pool_destroy(pool);
    /* Release the allocated global resources. */
    aos_http_io_deinitialize();
    return 0;
}

require 'aliyun/oss'

client = Aliyun::OSS::Client.new(
  # In this example, the endpoint of the China (Hangzhou) region is used. Specify your actual endpoint. 
  endpoint: 'https://oss-cn-hangzhou.aliyuncs.com',
  # 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. 
  access_key_id: ENV['OSS_ACCESS_KEY_ID'],
  access_key_secret: ENV['OSS_ACCESS_KEY_SECRET']
)

# Specify the name of the bucket. Example: examplebucket. 
bucket = client.get_bucket('examplebucket')
# Set key to the full path of the object. Do not include the bucket name in the full path. Example: exampledir/example.zip. 
# Set file to the full path of the local file. Example: /tmp/example.zip. 
bucket.resumable_download('exampledir/example.zip', '/tmp/example.zip') do |p|
  puts "Progress: #{p}"
end

bucket.resumable_download(
  'exampledir/example.zip', '/tmp/example.zip',
  # Set cpt_file to the path of the checkpoint file. 
  :part_size => 100 * 1024, :cpt_file => '/tmp/example.zip.cpt') { |p|
  puts "Progress: #{p}"
}