Utilizzo GetObject con un AWS SDK o una CLI

        /// <summary>
        /// Shows how to download an object from an Amazon S3 bucket to the
        /// local computer.
        /// </summary>
        /// <param name="client">An initialized Amazon S3 client object.</param>
        /// <param name="bucketName">The name of the bucket where the object is
        /// currently stored.</param>
        /// <param name="objectName">The name of the object to download.</param>
        /// <param name="filePath">The path, including filename, where the
        /// downloaded object will be stored.</param>
        /// <returns>A boolean value indicating the success or failure of the
        /// download process.</returns>
        public static async Task<bool> DownloadObjectFromBucketAsync(
            IAmazonS3 client,
            string bucketName,
            string objectName,
            string filePath)
        {
            // Create a GetObject request
            var request = new GetObjectRequest
            {
                BucketName = bucketName,
                Key = objectName,
            };

            // Issue request and remember to dispose of the response
            using GetObjectResponse response = await client.GetObjectAsync(request);

            try
            {
                // Save object to local file
                await response.WriteResponseStreamToFileAsync($"{filePath}\\{objectName}", true, CancellationToken.None);
                return response.HttpStatusCode == System.Net.HttpStatusCode.OK;
            }
            catch (AmazonS3Exception ex)
            {
                Console.WriteLine($"Error saving {objectName}: {ex.Message}");
                return false;
            }
        }

Ottieni un oggetto usando una richiesta condizionale.

    /// <summary>
    /// Retrieves an object from Amazon S3 with a conditional request.
    /// </summary>
    /// <param name="objectKey">The key of the object to retrieve.</param>
    /// <param name="sourceBucket">The source bucket of the object.</param>
    /// <param name="conditionType">The type of condition: 'IfMatch', 'IfNoneMatch', 'IfModifiedSince', 'IfUnmodifiedSince'.</param>
    /// <param name="conditionDateValue">The value to use for the condition for dates.</param>
    /// <param name="etagConditionalValue">The value to use for the condition for etags.</param>
    /// <returns>True if the conditional read is successful, False otherwise.</returns>
    public async Task<bool> GetObjectConditional(string objectKey, string sourceBucket,
        S3ConditionType conditionType, DateTime? conditionDateValue = null, string? etagConditionalValue = null)
    {
        try
        {
            var getObjectRequest = new GetObjectRequest
            {
                BucketName = sourceBucket,
                Key = objectKey
            };

            switch (conditionType)
            {
                case S3ConditionType.IfMatch:
                    getObjectRequest.EtagToMatch = etagConditionalValue;
                    break;
                case S3ConditionType.IfNoneMatch:
                    getObjectRequest.EtagToNotMatch = etagConditionalValue;
                    break;
                case S3ConditionType.IfModifiedSince:
                    getObjectRequest.ModifiedSinceDateUtc = conditionDateValue.GetValueOrDefault();
                    break;
                case S3ConditionType.IfUnmodifiedSince:
                    getObjectRequest.UnmodifiedSinceDateUtc = conditionDateValue.GetValueOrDefault();
                    break;
                default:
                    throw new ArgumentOutOfRangeException(nameof(conditionType), conditionType, null);
            }

            var response = await _amazonS3.GetObjectAsync(getObjectRequest);
            var sampleBytes = new byte[20];
            await response.ResponseStream.ReadAsync(sampleBytes, 0, 20);
            _logger.LogInformation($"Conditional read successful. Here are the first 20 bytes of the object:\n{System.Text.Encoding.UTF8.GetString(sampleBytes)}");
            return true;
        }
        catch (AmazonS3Exception e)
        {
            if (e.ErrorCode == "PreconditionFailed")
            {
                _logger.LogError("Conditional read failed: Precondition failed");
            }
            else if (e.ErrorCode == "NotModified")
            {
                _logger.LogError("Conditional read failed: Object not modified");
            }
            else
            {
                _logger.LogError($"Unexpected error: {e.ErrorCode}");
                throw;
            }
            return false;
        }
    }

###############################################################################
# function errecho
#
# This function outputs everything sent to it to STDERR (standard error output).
###############################################################################
function errecho() {
  printf "%s\n" "$*" 1>&2
}

###############################################################################
# function download_object_from_bucket
#
# This function downloads an object in a bucket to a file.
#
# Parameters:
#       $1 - The name of the bucket to download the object from.
#       $2 - The path and file name to store the downloaded bucket.
#       $3 - The key (name) of the object in the bucket.
#
# Returns:
#       0 - If successful.
#       1 - If it fails.
###############################################################################
function download_object_from_bucket() {
  local bucket_name=$1
  local destination_file_name=$2
  local object_name=$3
  local response

  response=$(aws s3api get-object \
    --bucket "$bucket_name" \
    --key "$object_name" \
    "$destination_file_name")

  # shellcheck disable=SC2181
  if [[ ${?} -ne 0 ]]; then
    errecho "ERROR: AWS reports put-object operation failed.\n$response"
    return 1
  fi
}

bool AwsDoc::S3::getObject(const Aws::String &objectKey,
                           const Aws::String &fromBucket,
                           const Aws::S3::S3ClientConfiguration &clientConfig) {
    Aws::S3::S3Client client(clientConfig);

    Aws::S3::Model::GetObjectRequest request;
    request.SetBucket(fromBucket);
    request.SetKey(objectKey);

    Aws::S3::Model::GetObjectOutcome outcome =
            client.GetObject(request);

    if (!outcome.IsSuccess()) {
        const Aws::S3::S3Error &err = outcome.GetError();
        std::cerr << "Error: getObject: " <<
                  err.GetExceptionName() << ": " << err.GetMessage() << std::endl;
    } else {
        std::cout << "Successfully retrieved '" << objectKey << "' from '"
                  << fromBucket << "'." << std::endl;
    }

    return outcome.IsSuccess();
}

L'esempio seguente utilizza il get-object comando per scaricare un oggetto da Amazon S3:

aws s3api get-object --bucket text-content --key dir/my_images.tar.bz2 my_images.tar.bz2

Tieni presente che il parametro outfile è specificato senza un nome di opzione come «--outfile». Il nome del file di output deve essere l'ultimo parametro del comando.

L'esempio seguente dimostra l'utilizzo di --range per scaricare un intervallo di byte specifico da un oggetto. Nota che gli intervalli di byte devono essere preceduti dal prefisso «bytes=»:

aws s3api get-object --bucket text-content --key dir/my_data --range bytes=8888-9999 my_data_range

Per ulteriori informazioni sul recupero di oggetti, consulta Getting Objects nella Amazon S3 Developer Guide.

import (
	"bytes"
	"context"
	"errors"
	"fmt"
	"io"
	"log"
	"os"
	"time"

	"github.com/aws/aws-sdk-go-v2/aws"
	"github.com/aws/aws-sdk-go-v2/feature/s3/manager"
	"github.com/aws/aws-sdk-go-v2/service/s3"
	"github.com/aws/aws-sdk-go-v2/service/s3/types"
	"github.com/aws/smithy-go"
)

// BucketBasics encapsulates the Amazon Simple Storage Service (Amazon S3) actions
// used in the examples.
// It contains S3Client, an Amazon S3 service client that is used to perform bucket
// and object actions.
type BucketBasics struct {
	S3Client *s3.Client
}



// DownloadFile gets an object from a bucket and stores it in a local file.
func (basics BucketBasics) DownloadFile(ctx context.Context, bucketName string, objectKey string, fileName string) error {
	result, err := basics.S3Client.GetObject(ctx, &s3.GetObjectInput{
		Bucket: aws.String(bucketName),
		Key:    aws.String(objectKey),
	})
	if err != nil {
		var noKey *types.NoSuchKey
		if errors.As(err, &noKey) {
			log.Printf("Can't get object %s from bucket %s. No such key exists.\n", objectKey, bucketName)
			err = noKey
		} else {
			log.Printf("Couldn't get object %v:%v. Here's why: %v\n", bucketName, objectKey, err)
		}
		return err
	}
	defer result.Body.Close()
	file, err := os.Create(fileName)
	if err != nil {
		log.Printf("Couldn't create file %v. Here's why: %v\n", fileName, err)
		return err
	}
	defer file.Close()
	body, err := io.ReadAll(result.Body)
	if err != nil {
		log.Printf("Couldn't read object body from %v. Here's why: %v\n", objectKey, err)
	}
	_, err = file.Write(body)
	return err
}

Leggi i dati come array di byte utilizzando un'interfaccia S3Client.

    /**
     * Asynchronously retrieves the bytes of an object from an Amazon S3 bucket and writes them to a local file.
     *
     * @param bucketName the name of the S3 bucket containing the object
     * @param keyName    the key (or name) of the S3 object to retrieve
     * @param path       the local file path where the object's bytes will be written
     * @return a {@link CompletableFuture} that completes when the object bytes have been written to the local file
     */
    public CompletableFuture<Void> getObjectBytesAsync(String bucketName, String keyName, String path) {
        GetObjectRequest objectRequest = GetObjectRequest.builder()
            .key(keyName)
            .bucket(bucketName)
            .build();

        CompletableFuture<ResponseBytes<GetObjectResponse>> response = getAsyncClient().getObject(objectRequest, AsyncResponseTransformer.toBytes());
        return response.thenAccept(objectBytes -> {
            try {
                byte[] data = objectBytes.asByteArray();
                Path filePath = Paths.get(path);
                Files.write(filePath, data);
                logger.info("Successfully obtained bytes from an S3 object");
            } catch (IOException ex) {
                throw new RuntimeException("Failed to write data to file", ex);
            }
        }).whenComplete((resp, ex) -> {
            if (ex != null) {
                throw new RuntimeException("Failed to get object bytes from S3", ex);
            }
        });
    }

Usa un S3 TransferManager per scaricare un oggetto in un bucket S3 in un file locale. Visualizza il file completo ed esegui il test.

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import software.amazon.awssdk.core.sync.RequestBody;
import software.amazon.awssdk.transfer.s3.S3TransferManager;
import software.amazon.awssdk.transfer.s3.model.CompletedFileDownload;
import software.amazon.awssdk.transfer.s3.model.DownloadFileRequest;
import software.amazon.awssdk.transfer.s3.model.FileDownload;
import software.amazon.awssdk.transfer.s3.progress.LoggingTransferListener;

import java.io.IOException;
import java.net.URISyntaxException;
import java.net.URL;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.UUID;

    public Long downloadFile(S3TransferManager transferManager, String bucketName,
                             String key, String downloadedFileWithPath) {
        DownloadFileRequest downloadFileRequest = DownloadFileRequest.builder()
                .getObjectRequest(b -> b.bucket(bucketName).key(key))
                .destination(Paths.get(downloadedFileWithPath))
                .build();

        FileDownload downloadFile = transferManager.downloadFile(downloadFileRequest);

        CompletedFileDownload downloadResult = downloadFile.completionFuture().join();
        logger.info("Content length [{}]", downloadResult.response().contentLength());
        return downloadResult.response().contentLength();
    }

Leggi i tag appartenenti a un oggetto utilizzando un'interfaccia S3Client.

import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.s3.S3Client;
import software.amazon.awssdk.services.s3.model.GetObjectTaggingRequest;
import software.amazon.awssdk.services.s3.model.GetObjectTaggingResponse;
import software.amazon.awssdk.services.s3.model.S3Exception;
import software.amazon.awssdk.services.s3.model.Tag;

import java.util.List;

/**
 * Before running this Java V2 code example, set up your development
 * environment, including your credentials.
 * <p>
 * For more information, see the following documentation topic:
 * <p>
 * https://docs.aws.amazon.com/sdk-for-java/latest/developer-guide/get-started.html
 */

public class GetObjectTags {
    public static void main(String[] args) {
        final String usage = """

            Usage:
                <bucketName> <keyName>\s

            Where:
                bucketName - The Amazon S3 bucket name.\s
                keyName - A key name that represents the object.\s
            """;

        if (args.length != 2) {
            System.out.println(usage);
            System.exit(1);
        }

        String bucketName = args[0];
        String keyName = args[1];
        Region region = Region.US_EAST_1;
        S3Client s3 = S3Client.builder()
            .region(region)
            .build();

        listTags(s3, bucketName, keyName);
        s3.close();
    }

    /**
     * Lists the tags associated with an Amazon S3 object.
     *
     * @param s3 the S3Client object used to interact with the Amazon S3 service
     * @param bucketName the name of the S3 bucket that contains the object
     * @param keyName the key (name) of the S3 object
     */
    public static void listTags(S3Client s3, String bucketName, String keyName) {
        try {
            GetObjectTaggingRequest getTaggingRequest = GetObjectTaggingRequest
                .builder()
                .key(keyName)
                .bucket(bucketName)
                .build();

            GetObjectTaggingResponse tags = s3.getObjectTagging(getTaggingRequest);
            List<Tag> tagSet = tags.tagSet();
            for (Tag tag : tagSet) {
                System.out.println(tag.key());
                System.out.println(tag.value());
            }

        } catch (S3Exception e) {
            System.err.println(e.awsErrorDetails().errorMessage());
            System.exit(1);
        }
    }
}

Recupera un URL per un oggetto utilizzando un'interfaccia S3Client.

import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.s3.S3Client;
import software.amazon.awssdk.services.s3.model.GetUrlRequest;
import software.amazon.awssdk.services.s3.model.S3Exception;

import java.net.URL;

/**
 * Before running this Java V2 code example, set up your development
 * environment, including your credentials.
 * <p>
 * For more information, see the following documentation topic:
 * <p>
 * https://docs.aws.amazon.com/sdk-for-java/latest/developer-guide/get-started.html
 */

public class GetObjectUrl {
    public static void main(String[] args) {
        final String usage = """

            Usage:
                <bucketName> <keyName>\s

            Where:
                bucketName - The Amazon S3 bucket name.
                keyName - A key name that represents the object.\s
            """;

        if (args.length != 2) {
            System.out.println(usage);
            System.exit(1);
        }

        String bucketName = args[0];
        String keyName = args[1];
        Region region = Region.US_EAST_1;
        S3Client s3 = S3Client.builder()
            .region(region)
            .build();

        getURL(s3, bucketName, keyName);
        s3.close();
    }

    /**
     * Retrieves the URL for a specific object in an Amazon S3 bucket.
     *
     * @param s3 the S3Client object used to interact with the Amazon S3 service
     * @param bucketName the name of the S3 bucket where the object is stored
     * @param keyName the name of the object for which the URL should be retrieved
     * @throws S3Exception if there is an error retrieving the URL for the specified object
     */
    public static void getURL(S3Client s3, String bucketName, String keyName) {
        try {
            GetUrlRequest request = GetUrlRequest.builder()
                .bucket(bucketName)
                .key(keyName)
                .build();

            URL url = s3.utilities().getUrl(request);
            System.out.println("The URL for  " + keyName + " is " + url);

        } catch (S3Exception e) {
            System.err.println(e.awsErrorDetails().errorMessage());
            System.exit(1);
        }
    }
}

Recupera un oggetto utilizzando l'oggetto client S3Presigner mediante un'interfaccia S3Client.

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.HttpURLConnection;
import java.time.Duration;

import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.s3.model.GetObjectRequest;
import software.amazon.awssdk.services.s3.model.S3Exception;
import software.amazon.awssdk.services.s3.presigner.model.GetObjectPresignRequest;
import software.amazon.awssdk.services.s3.presigner.model.PresignedGetObjectRequest;
import software.amazon.awssdk.services.s3.presigner.S3Presigner;
import software.amazon.awssdk.utils.IoUtils;

/**
 * Before running this Java V2 code example, set up your development
 * environment, including your credentials.
 * <p>
 * For more information, see the following documentation topic:
 * <p>
 * https://docs.aws.amazon.com/sdk-for-java/latest/developer-guide/get-started.html
 */
public class GetObjectPresignedUrl {
    public static void main(String[] args) {
        final String USAGE = """

            Usage:
                <bucketName> <keyName>\s

            Where:
                bucketName - The Amazon S3 bucket name.\s
                keyName - A key name that represents a text file.\s
            """;

        if (args.length != 2) {
            System.out.println(USAGE);
            System.exit(1);
        }

        String bucketName = args[0];
        String keyName = args[1];
        Region region = Region.US_EAST_1;
        S3Presigner presigner = S3Presigner.builder()
            .region(region)
            .build();

        getPresignedUrl(presigner, bucketName, keyName);
        presigner.close();
    }

    /**
     * Generates a pre-signed URL for an Amazon S3 object.
     *
     * @param presigner The {@link S3Presigner} instance to use for generating the pre-signed URL.
     * @param bucketName The name of the Amazon S3 bucket where the object is stored.
     * @param keyName The key name (file name) of the object in the Amazon S3 bucket.
     *
     * @throws S3Exception If there is an error interacting with the Amazon S3 service.
     * @throws IOException If there is an error opening the HTTP connection or reading/writing the request/response.
     */
    public static void getPresignedUrl(S3Presigner presigner, String bucketName, String keyName) {
        try {
            GetObjectRequest getObjectRequest = GetObjectRequest.builder()
                .bucket(bucketName)
                .key(keyName)
                .build();

            GetObjectPresignRequest getObjectPresignRequest = GetObjectPresignRequest.builder()
                .signatureDuration(Duration.ofMinutes(60))
                .getObjectRequest(getObjectRequest)
                .build();

            PresignedGetObjectRequest presignedGetObjectRequest = presigner.presignGetObject(getObjectPresignRequest);
            String theUrl = presignedGetObjectRequest.url().toString();
            System.out.println("Presigned URL: " + theUrl);
            HttpURLConnection connection = (HttpURLConnection) presignedGetObjectRequest.url().openConnection();
            presignedGetObjectRequest.httpRequest().headers().forEach((header, values) -> {
                values.forEach(value -> {
                    connection.addRequestProperty(header, value);
                });
            });

            // Send any request payload that the service needs (not needed when
            // isBrowserExecutable is true).
            if (presignedGetObjectRequest.signedPayload().isPresent()) {
                connection.setDoOutput(true);

                try (InputStream signedPayload = presignedGetObjectRequest.signedPayload().get().asInputStream();
                     OutputStream httpOutputStream = connection.getOutputStream()) {
                    IoUtils.copy(signedPayload, httpOutputStream);
                }
            }

            // Download the result of executing the request.
            try (InputStream content = connection.getInputStream()) {
                System.out.println("Service returned response: ");
                IoUtils.copy(content, System.out);
            }

        } catch (S3Exception | IOException e) {
            e.getStackTrace();
        }
    }
}

Ottieni un oggetto usando un ResponseTransformer oggetto e S3Client.

import software.amazon.awssdk.core.ResponseBytes;
import software.amazon.awssdk.core.sync.ResponseTransformer;
import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.s3.S3Client;
import software.amazon.awssdk.services.s3.model.GetObjectRequest;
import software.amazon.awssdk.services.s3.model.S3Exception;
import software.amazon.awssdk.services.s3.model.GetObjectResponse;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;

/**
 * Before running this Java V2 code example, set up your development
 * environment, including your credentials.
 * <p>
 * For more information, see the following documentation topic:
 * <p>
 * https://docs.aws.amazon.com/sdk-for-java/latest/developer-guide/get-started.html
 */

public class GetObjectData {
    public static void main(String[] args) {
        final String usage = """

            Usage:
                <bucketName> <keyName> <path>

            Where:
                bucketName - The Amazon S3 bucket name.\s
                keyName - The key name.\s
                path - The path where the file is written to.\s
            """;

        if (args.length != 3) {
            System.out.println(usage);
            System.exit(1);
        }

        String bucketName = args[0];
        String keyName = args[1];
        String path = args[2];
        Region region = Region.US_EAST_1;
        S3Client s3 = S3Client.builder()
            .region(region)
            .build();

        getObjectBytes(s3, bucketName, keyName, path);
        s3.close();
    }

    /**
     * Retrieves the bytes of an object stored in an Amazon S3 bucket and saves them to a local file.
     *
     * @param s3 The S3Client instance used to interact with the Amazon S3 service.
     * @param bucketName The name of the S3 bucket where the object is stored.
     * @param keyName The key (or name) of the S3 object.
     * @param path The local file path where the object's bytes will be saved.
     * @throws IOException If an I/O error occurs while writing the bytes to the local file.
     * @throws S3Exception If an error occurs while retrieving the object from the S3 bucket.
     */
    public static void getObjectBytes(S3Client s3, String bucketName, String keyName, String path) {
        try {
            GetObjectRequest objectRequest = GetObjectRequest
                .builder()
                .key(keyName)
                .bucket(bucketName)
                .build();

            ResponseBytes<GetObjectResponse> objectBytes = s3.getObject(objectRequest, ResponseTransformer.toBytes());
            byte[] data = objectBytes.asByteArray();

            // Write the data to a local file.
            File myFile = new File(path);
            OutputStream os = new FileOutputStream(myFile);
            os.write(data);
            System.out.println("Successfully obtained bytes from an S3 object");
            os.close();

        } catch (IOException ex) {
            ex.printStackTrace();
        } catch (S3Exception e) {
            System.err.println(e.awsErrorDetails().errorMessage());
            System.exit(1);
        }
    }
}

Scarica l'oggetto.

import {
  GetObjectCommand,
  NoSuchKey,
  S3Client,
  S3ServiceException,
} from "@aws-sdk/client-s3";

/**
 * Get a single object from a specified S3 bucket.
 * @param {{ bucketName: string, key: string }}
 */
export const main = async ({ bucketName, key }) => {
  const client = new S3Client({});

  try {
    const response = await client.send(
      new GetObjectCommand({
        Bucket: bucketName,
        Key: key,
      }),
    );
    // The Body object also has 'transformToByteArray' and 'transformToWebStream' methods.
    const str = await response.Body.transformToString();
    console.log(str);
  } catch (caught) {
    if (caught instanceof NoSuchKey) {
      console.error(
        `Error from S3 while getting object "${key}" from "${bucketName}". No such key exists.`,
      );
    } else if (caught instanceof S3ServiceException) {
      console.error(
        `Error from S3 while getting object from ${bucketName}.  ${caught.name}: ${caught.message}`,
      );
    } else {
      throw caught;
    }
  }
};

Scarica l'oggetto a condizione ETag che non corrisponda a quello fornito.

import {
  GetObjectCommand,
  NoSuchKey,
  S3Client,
  S3ServiceException,
} from "@aws-sdk/client-s3";

/**
 * Get a single object from a specified S3 bucket.
 * @param {{ bucketName: string, key: string, eTag: string }}
 */
export const main = async ({ bucketName, key, eTag }) => {
  const client = new S3Client({});

  try {
    const response = await client.send(
      new GetObjectCommand({
        Bucket: bucketName,
        Key: key,
        IfMatch: eTag,
      }),
    );
    // The Body object also has 'transformToByteArray' and 'transformToWebStream' methods.
    const str = await response.Body.transformToString();
    console.log("Success. Here is text of the file:", str);
  } catch (caught) {
    if (caught instanceof NoSuchKey) {
      console.error(
        `Error from S3 while getting object "${key}" from "${bucketName}". No such key exists.`,
      );
    } else if (caught instanceof S3ServiceException) {
      console.error(
        `Error from S3 while getting object from ${bucketName}.  ${caught.name}: ${caught.message}`,
      );
    } else {
      throw caught;
    }
  }
};

// Call function if run directly
import { parseArgs } from "node:util";
import {
  isMain,
  validateArgs,
} from "@aws-doc-sdk-examples/lib/utils/util-node.js";

const loadArgs = () => {
  const options = {
    bucketName: {
      type: "string",
      required: true,
    },
    key: {
      type: "string",
      required: true,
    },
    eTag: {
      type: "string",
      required: true,
    },
  };
  const results = parseArgs({ options });
  const { errors } = validateArgs({ options }, results);
  return { errors, results };
};

if (isMain(import.meta.url)) {
  const { errors, results } = loadArgs();
  if (!errors) {
    main(results.values);
  } else {
    console.error(errors.join("\n"));
  }
}

Scarica l'oggetto a condizione ETag che non corrisponda a quello fornito.

import {
  GetObjectCommand,
  NoSuchKey,
  S3Client,
  S3ServiceException,
} from "@aws-sdk/client-s3";

/**
 * Get a single object from a specified S3 bucket.
 * @param {{ bucketName: string, key: string, eTag: string }}
 */
export const main = async ({ bucketName, key, eTag }) => {
  const client = new S3Client({});

  try {
    const response = await client.send(
      new GetObjectCommand({
        Bucket: bucketName,
        Key: key,
        IfNoneMatch: eTag,
      }),
    );
    // The Body object also has 'transformToByteArray' and 'transformToWebStream' methods.
    const str = await response.Body.transformToString();
    console.log("Success. Here is text of the file:", str);
  } catch (caught) {
    if (caught instanceof NoSuchKey) {
      console.error(
        `Error from S3 while getting object "${key}" from "${bucketName}". No such key exists.`,
      );
    } else if (caught instanceof S3ServiceException) {
      console.error(
        `Error from S3 while getting object from ${bucketName}. ${caught.name}: ${caught.message}`,
      );
    } else {
      throw caught;
    }
  }
};

// Call function if run directly
import { parseArgs } from "node:util";
import {
  isMain,
  validateArgs,
} from "@aws-doc-sdk-examples/lib/utils/util-node.js";

const loadArgs = () => {
  const options = {
    bucketName: {
      type: "string",
      required: true,
    },
    key: {
      type: "string",
      required: true,
    },
    eTag: {
      type: "string",
      required: true,
    },
  };
  const results = parseArgs({ options });
  const { errors } = validateArgs({ options }, results);
  return { errors, results };
};

if (isMain(import.meta.url)) {
  const { errors, results } = loadArgs();
  if (!errors) {
    main(results.values);
  } else {
    console.error(errors.join("\n"));
  }
}

Scarica l'oggetto a condizione che sia stato creato o modificato in un determinato periodo di tempo.

import {
  GetObjectCommand,
  NoSuchKey,
  S3Client,
  S3ServiceException,
} from "@aws-sdk/client-s3";

/**
 * Get a single object from a specified S3 bucket.
 * @param {{ bucketName: string, key: string }}
 */
export const main = async ({ bucketName, key }) => {
  const client = new S3Client({});
  const date = new Date();
  date.setDate(date.getDate() - 1);
  try {
    const response = await client.send(
      new GetObjectCommand({
        Bucket: bucketName,
        Key: key,
        IfModifiedSince: date,
      }),
    );
    // The Body object also has 'transformToByteArray' and 'transformToWebStream' methods.
    const str = await response.Body.transformToString();
    console.log("Success. Here is text of the file:", str);
  } catch (caught) {
    if (caught instanceof NoSuchKey) {
      console.error(
        `Error from S3 while getting object "${key}" from "${bucketName}". No such key exists.`,
      );
    } else if (caught instanceof S3ServiceException) {
      console.error(
        `Error from S3 while getting object from ${bucketName}.  ${caught.name}: ${caught.message}`,
      );
    } else {
      throw caught;
    }
  }
};

// Call function if run directly
import { parseArgs } from "node:util";
import {
  isMain,
  validateArgs,
} from "@aws-doc-sdk-examples/lib/utils/util-node.js";

const loadArgs = () => {
  const options = {
    bucketName: {
      type: "string",
      required: true,
    },
    key: {
      type: "string",
      required: true,
    },
  };
  const results = parseArgs({ options });
  const { errors } = validateArgs({ options }, results);
  return { errors, results };
};

if (isMain(import.meta.url)) {
  const { errors, results } = loadArgs();
  if (!errors) {
    main(results.values);
  } else {
    console.error(errors.join("\n"));
  }
}

Scarica l'oggetto a condizione che non sia stato creato o modificato in un determinato periodo di tempo.

import {
  GetObjectCommand,
  NoSuchKey,
  S3Client,
  S3ServiceException,
} from "@aws-sdk/client-s3";

/**
 * Get a single object from a specified S3 bucket.
 * @param {{ bucketName: string, key: string }}
 */
export const main = async ({ bucketName, key }) => {
  const client = new S3Client({});
  const date = new Date();
  date.setDate(date.getDate() - 1);
  try {
    const response = await client.send(
      new GetObjectCommand({
        Bucket: bucketName,
        Key: key,
        IfUnmodifiedSince: date,
      }),
    );
    // The Body object also has 'transformToByteArray' and 'transformToWebStream' methods.
    const str = await response.Body.transformToString();
    console.log("Success. Here is text of the file:", str);
  } catch (caught) {
    if (caught instanceof NoSuchKey) {
      console.error(
        `Error from S3 while getting object "${key}" from "${bucketName}". No such key exists.`,
      );
    } else if (caught instanceof S3ServiceException) {
      console.error(
        `Error from S3 while getting object from ${bucketName}.  ${caught.name}: ${caught.message}`,
      );
    } else {
      throw caught;
    }
  }
};

// Call function if run directly
import { parseArgs } from "node:util";
import {
  isMain,
  validateArgs,
} from "@aws-doc-sdk-examples/lib/utils/util-node.js";

const loadArgs = () => {
  const options = {
    bucketName: {
      type: "string",
      required: true,
    },
    key: {
      type: "string",
      required: true,
    },
  };
  const results = parseArgs({ options });
  const { errors } = validateArgs({ options }, results);
  return { errors, results };
};

if (isMain(import.meta.url)) {
  const { errors, results } = loadArgs();
  if (!errors) {
    main(results.values);
  } else {
    console.error(errors.join("\n"));
  }
}

suspend fun getObjectBytes(
    bucketName: String,
    keyName: String,
    path: String,
) {
    val request =
        GetObjectRequest {
            key = keyName
            bucket = bucketName
        }

    S3Client { region = "us-east-1" }.use { s3 ->
        s3.getObject(request) { resp ->
            val myFile = File(path)
            resp.body?.writeToFile(myFile)
            println("Successfully read $keyName from $bucketName")
        }
    }
}

Recupera un oggetto.

        $s3client = new Aws\S3\S3Client(['region' => 'us-west-2']);

        try {
            $file = $this->s3client->getObject([
                'Bucket' => $this->bucketName,
                'Key' => $fileName,
            ]);
            $body = $file->get('Body');
            $body->rewind();
            echo "Downloaded the file and it begins with: {$body->read(26)}.\n";
        } catch (Exception $exception) {
            echo "Failed to download $fileName from $this->bucketName with error: " . $exception->getMessage();
            exit("Please fix error with file downloading before continuing.");
        }

Esempio 1: Questo comando recupera l'elemento "sample.txt" dal bucket «test-files» e lo salva in un file denominato "local-sample.txt" nella posizione corrente. Il file "local-sample.txt" non deve esistere prima che questo comando venga chiamato.

Read-S3Object -BucketName amzn-s3-demo-bucket -Key sample.txt -File local-sample.txt

Esempio 2: Questo comando recupera la directory virtuale «DIR» dal bucket «test-files» e la salva in una cartella denominata «Local-dir» nella posizione corrente. La cartella «Local-dir» non deve esistere prima che questo comando venga chiamato.

Read-S3Object -BucketName amzn-s3-demo-bucket -KeyPrefix DIR -Folder Local-DIR

Esempio 3: scarica tutti gli oggetti con chiavi che terminano con '.json' dai bucket con 'config' nel nome del bucket ai file nella cartella specificata. Le chiavi degli oggetti vengono utilizzate per impostare i nomi dei file.

Get-S3Bucket | ? { $_.BucketName -like '*config*' } | Get-S3Object | ? { $_.Key -like '*.json' } | Read-S3Object -Folder C:\ConfigObjects

class ObjectWrapper:
    """Encapsulates S3 object actions."""

    def __init__(self, s3_object):
        """
        :param s3_object: A Boto3 Object resource. This is a high-level resource in Boto3
                          that wraps object actions in a class-like structure.
        """
        self.object = s3_object
        self.key = self.object.key


    def get(self):
        """
        Gets the object.

        :return: The object data in bytes.
        """
        try:
            body = self.object.get()["Body"].read()
            logger.info(
                "Got object '%s' from bucket '%s'.",
                self.object.key,
                self.object.bucket_name,
            )
        except ClientError:
            logger.exception(
                "Couldn't get object '%s' from bucket '%s'.",
                self.object.key,
                self.object.bucket_name,
            )
            raise
        else:
            return body

Ottieni un oggetto usando una richiesta condizionale.

class S3ConditionalRequests:
    """Encapsulates S3 conditional request operations."""

    def __init__(self, s3_client):
        self.s3 = s3_client

    @classmethod
    def from_client(cls):
        """
        Instantiates this class from a Boto3 client.
        """
        s3_client = boto3.client("s3")
        return cls(s3_client)



    def get_object_conditional(
        self,
        object_key: str,
        source_bucket: str,
        condition_type: str,
        condition_value: str,
    ):
        """
        Retrieves an object from Amazon S3 with a conditional request.

        :param object_key: The key of the object to retrieve.
        :param source_bucket: The source bucket of the object.
        :param condition_type: The type of condition: 'IfMatch', 'IfNoneMatch', 'IfModifiedSince', 'IfUnmodifiedSince'.
        :param condition_value: The value to use for the condition.
        """
        try:
            response = self.s3.get_object(
                Bucket=source_bucket,
                Key=object_key,
                **{condition_type: condition_value},
            )
            sample_bytes = response["Body"].read(20)
            print(
                f"\tConditional read successful. Here are the first 20 bytes of the object:\n"
            )
            print(f"\t{sample_bytes}")
        except ClientError as e:
            error_code = e.response["Error"]["Code"]
            if error_code == "PreconditionFailed":
                print("\tConditional read failed: Precondition failed")
            elif error_code == "304":  # Not modified error code.
                print("\tConditional read failed: Object not modified")
            else:
                logger.error(f"Unexpected error: {error_code}")
                raise

Recupera un oggetto.

require 'aws-sdk-s3'

# Wraps Amazon S3 object actions.
class ObjectGetWrapper
  attr_reader :object

  # @param object [Aws::S3::Object] An existing Amazon S3 object.
  def initialize(object)
    @object = object
  end

  # Gets the object directly to a file.
  #
  # @param target_path [String] The path to the file where the object is downloaded.
  # @return [Aws::S3::Types::GetObjectOutput, nil] The retrieved object data if successful; otherwise nil.
  def get_object(target_path)
    @object.get(response_target: target_path)
  rescue Aws::Errors::ServiceError => e
    puts "Couldn't get object #{@object.key}. Here's why: #{e.message}"
  end
end

# Example usage:
def run_demo
  bucket_name = "amzn-s3-demo-bucket"
  object_key = "my-object.txt"
  target_path = "my-object-as-file.txt"

  wrapper = ObjectGetWrapper.new(Aws::S3::Object.new(bucket_name, object_key))
  obj_data = wrapper.get_object(target_path)
  return unless obj_data

  puts "Object #{object_key} (#{obj_data.content_length} bytes} downloaded to #{target_path}."
end

run_demo if $PROGRAM_NAME == __FILE__

Recupera un oggetto e segnala lo stato di crittografia lato server.

require 'aws-sdk-s3'

# Wraps Amazon S3 object actions.
class ObjectGetEncryptionWrapper
  attr_reader :object

  # @param object [Aws::S3::Object] An existing Amazon S3 object.
  def initialize(object)
    @object = object
  end

  # Gets the object into memory.
  #
  # @return [Aws::S3::Types::GetObjectOutput, nil] The retrieved object data if successful; otherwise nil.
  def object
    @object.get
  rescue Aws::Errors::ServiceError => e
    puts "Couldn't get object #{@object.key}. Here's why: #{e.message}"
  end
end

# Example usage:
def run_demo
  bucket_name = "amzn-s3-demo-bucket"
  object_key = "my-object.txt"

  wrapper = ObjectGetEncryptionWrapper.new(Aws::S3::Object.new(bucket_name, object_key))
  obj_data = wrapper.get_object
  return unless obj_data

  encryption = obj_data.server_side_encryption.nil? ? 'no' : obj_data.server_side_encryption
  puts "Object #{object_key} uses #{encryption} encryption."
end

run_demo if $PROGRAM_NAME == __FILE__

async fn get_object(client: Client, opt: Opt) -> Result<usize, S3ExampleError> {
    trace!("bucket:      {}", opt.bucket);
    trace!("object:      {}", opt.object);
    trace!("destination: {}", opt.destination.display());

    let mut file = File::create(opt.destination.clone()).map_err(|err| {
        S3ExampleError::new(format!(
            "Failed to initialize file for saving S3 download: {err:?}"
        ))
    })?;

    let mut object = client
        .get_object()
        .bucket(opt.bucket)
        .key(opt.object)
        .send()
        .await?;

    let mut byte_count = 0_usize;
    while let Some(bytes) = object.body.try_next().await.map_err(|err| {
        S3ExampleError::new(format!("Failed to read from S3 download stream: {err:?}"))
    })? {
        let bytes_len = bytes.len();
        file.write_all(&bytes).map_err(|err| {
            S3ExampleError::new(format!(
                "Failed to write from S3 download stream to local file: {err:?}"
            ))
        })?;
        trace!("Intermediate write of {bytes_len}");
        byte_count += bytes_len;
    }

    Ok(byte_count)
}

    TRY.
        oo_result = lo_s3->getobject(           " oo_result is returned for testing purposes. "
                  iv_bucket = iv_bucket_name
                  iv_key = iv_object_key
               ).
        DATA(lv_object_data) = oo_result->get_body( ).
        MESSAGE 'Object retrieved from S3 bucket.' TYPE 'I'.
      CATCH /aws1/cx_s3_nosuchbucket.
        MESSAGE 'Bucket does not exist.' TYPE 'E'.
      CATCH /aws1/cx_s3_nosuchkey.
        MESSAGE 'Object key does not exist.' TYPE 'E'.
    ENDTRY.

import AWSS3

    public func downloadFile(bucket: String, key: String, to: String) async throws {
        let fileUrl = URL(fileURLWithPath: to).appendingPathComponent(key)

        let input = GetObjectInput(
            bucket: bucket,
            key: key
        )
        do {
            let output = try await client.getObject(input: input)

            guard let body = output.body else {
                throw HandlerError.getObjectBody("GetObjectInput missing body.")
            }

            guard let data = try await body.readData() else {
                throw HandlerError.readGetObjectBody("GetObjectInput unable to read data.")
            }

            try data.write(to: fileUrl)
        }
        catch {
            print("ERROR: ", dump(error, name: "Downloading a file."))
            throw error
        }
    }

import AWSS3

    public func readFile(bucket: String, key: String) async throws -> Data {
        let input = GetObjectInput(
            bucket: bucket,
            key: key
        )
        do {
            let output = try await client.getObject(input: input)
            
            guard let body = output.body else {
                throw HandlerError.getObjectBody("GetObjectInput missing body.")
            }

            guard let data = try await body.readData() else {
                throw HandlerError.readGetObjectBody("GetObjectInput unable to read data.")
            }

            return data
        }
        catch {
            print("ERROR: ", dump(error, name: "Reading a file."))
            throw error
        }
   }