Firma in anticipo per un download Firma preventivamente per un caricamento

Lavora con URL Amazon S3 prefirmati

Gli URL prefirmati forniscono l'accesso temporaneo agli oggetti S3 privati senza richiedere agli utenti di disporre di AWS credenziali o autorizzazioni.

Ad esempio, si supponga che Alice abbia accesso a un oggetto S3 e che voglia condividere temporaneamente l'accesso a quell'oggetto con Bob. Alice può generare una richiesta GET prefirmata da condividere con Bob in modo che possa scaricare l'oggetto senza richiedere l'accesso alle credenziali di Alice. È possibile generare URL prefirmati per HTTP GET e per richieste HTTP PUT.

Genera un URL prefirmato per un oggetto, quindi scaricalo (richiesta GET)

L'esempio seguente è composto da due parti.

Parte 1: Alice genera l'URL prefirmato per un oggetto.
Parte 2: Bob scarica l'oggetto utilizzando l'URL prefirmato.

Parte 1: Generazione dell'URL

Alice ha già un oggetto in un bucket S3. Usa il codice seguente per generare una stringa URL che Bob può utilizzare in una successiva richiesta GET.


import com.example.s3.util.PresignUrlUtils;
import org.slf4j.Logger;
import software.amazon.awssdk.http.HttpExecuteRequest;
import software.amazon.awssdk.http.HttpExecuteResponse;
import software.amazon.awssdk.http.SdkHttpClient;
import software.amazon.awssdk.http.SdkHttpMethod;
import software.amazon.awssdk.http.SdkHttpRequest;
import software.amazon.awssdk.http.apache.ApacheHttpClient;
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.presigner.S3Presigner;
import software.amazon.awssdk.services.s3.presigner.model.GetObjectPresignRequest;
import software.amazon.awssdk.services.s3.presigner.model.PresignedGetObjectRequest;
import software.amazon.awssdk.utils.IoUtils;

import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URISyntaxException;
import java.net.URL;
import java.net.http.HttpClient;
import java.net.http.HttpRequest;
import java.net.http.HttpResponse;
import java.nio.file.Paths;
import java.time.Duration;
import java.util.UUID;


    /* Create a pre-signed URL to download an object in a subsequent GET request. */
    public String createPresignedGetUrl(String bucketName, String keyName) {
        try (S3Presigner presigner = S3Presigner.create()) {

            GetObjectRequest objectRequest = GetObjectRequest.builder()
                    .bucket(bucketName)
                    .key(keyName)
                    .build();

            GetObjectPresignRequest presignRequest = GetObjectPresignRequest.builder()
                    .signatureDuration(Duration.ofMinutes(10))  // The URL will expire in 10 minutes.
                    .getObjectRequest(objectRequest)
                    .build();

            PresignedGetObjectRequest presignedRequest = presigner.presignGetObject(presignRequest);
            logger.info("Presigned URL: [{}]", presignedRequest.url().toString());
            logger.info("HTTP method: [{}]", presignedRequest.httpRequest().method());

            return presignedRequest.url().toExternalForm();
        }
    }

Parte 2: scarica l'oggetto

Bob utilizza una delle seguenti tre opzioni di codice per scaricare l'oggetto. In alternativa, potrebbe utilizzare un browser per eseguire la richiesta GET.


    /* Use the JDK HttpURLConnection (since v1.1) class to do the download. */
    public byte[] useHttpUrlConnectionToGet(String presignedUrlString) {
        ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream(); // Capture the response body to a byte array.

        try {
            URL presignedUrl = new URL(presignedUrlString);
            HttpURLConnection connection = (HttpURLConnection) presignedUrl.openConnection();
            connection.setRequestMethod("GET");
            // Download the result of executing the request.
            try (InputStream content = connection.getInputStream()) {
                IoUtils.copy(content, byteArrayOutputStream);
            }
            logger.info("HTTP response code is " + connection.getResponseCode());

        } catch (S3Exception | IOException e) {
            logger.error(e.getMessage(), e);
        }
        return byteArrayOutputStream.toByteArray();
    }


    /* Use the JDK HttpClient (since v11) class to do the download. */
    public byte[] useHttpClientToGet(String presignedUrlString) {
        ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream(); // Capture the response body to a byte array.

        HttpRequest.Builder requestBuilder = HttpRequest.newBuilder();
        HttpClient httpClient = HttpClient.newHttpClient();
        try {
            URL presignedUrl = new URL(presignedUrlString);
            HttpResponse<InputStream> response = httpClient.send(requestBuilder
                            .uri(presignedUrl.toURI())
                            .GET()
                            .build(),
                    HttpResponse.BodyHandlers.ofInputStream());

            IoUtils.copy(response.body(), byteArrayOutputStream);

            logger.info("HTTP response code is " + response.statusCode());

        } catch (URISyntaxException | InterruptedException | IOException e) {
            logger.error(e.getMessage(), e);
        }
        return byteArrayOutputStream.toByteArray();
    }


    /* Use the AWS SDK for Java SdkHttpClient class to do the download. */
    public byte[] useSdkHttpClientToPut(String presignedUrlString) {

        ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream(); // Capture the response body to a byte array.
        try {
            URL presignedUrl = new URL(presignedUrlString);
            SdkHttpRequest request = SdkHttpRequest.builder()
                    .method(SdkHttpMethod.GET)
                    .uri(presignedUrl.toURI())
                    .build();

            HttpExecuteRequest executeRequest = HttpExecuteRequest.builder()
                    .request(request)
                    .build();

            try (SdkHttpClient sdkHttpClient = ApacheHttpClient.create()) {
                HttpExecuteResponse response = sdkHttpClient.prepareRequest(executeRequest).call();
                response.responseBody().ifPresentOrElse(
                        abortableInputStream -> {
                            try {
                                IoUtils.copy(abortableInputStream, byteArrayOutputStream);
                            } catch (IOException e) {
                                throw new RuntimeException(e);
                            }
                        },
                        () -> logger.error("No response body."));

                logger.info("HTTP Response code is {}", response.httpResponse().statusCode());
            }
        } catch (URISyntaxException | IOException e) {
            logger.error(e.getMessage(), e);
        }
        return byteArrayOutputStream.toByteArray();
    }

Guarda l'esempio completo e prosegui il test. GitHub

Genera un URL prefirmato per un caricamento, quindi carica un file (richiesta PUT)

L'esempio seguente è composto da due parti.

Parte 1: Alice genera l'URL prefirmato per caricare un oggetto.
Parte 2: Bob carica un file utilizzando l'URL prefirmato.

Parte 1: Generazione dell'URL

Alice ha già un bucket S3. Usa il codice seguente per generare una stringa URL che Bob può utilizzare in una successiva richiesta PUT.


import com.example.s3.util.PresignUrlUtils;
import org.slf4j.Logger;
import software.amazon.awssdk.core.internal.sync.FileContentStreamProvider;
import software.amazon.awssdk.http.HttpExecuteRequest;
import software.amazon.awssdk.http.HttpExecuteResponse;
import software.amazon.awssdk.http.SdkHttpClient;
import software.amazon.awssdk.http.SdkHttpMethod;
import software.amazon.awssdk.http.SdkHttpRequest;
import software.amazon.awssdk.http.apache.ApacheHttpClient;
import software.amazon.awssdk.services.s3.S3Client;
import software.amazon.awssdk.services.s3.model.PutObjectRequest;
import software.amazon.awssdk.services.s3.model.S3Exception;
import software.amazon.awssdk.services.s3.presigner.S3Presigner;
import software.amazon.awssdk.services.s3.presigner.model.PresignedPutObjectRequest;
import software.amazon.awssdk.services.s3.presigner.model.PutObjectPresignRequest;

import java.io.File;
import java.io.IOException;
import java.io.OutputStream;
import java.io.RandomAccessFile;
import java.net.HttpURLConnection;
import java.net.URISyntaxException;
import java.net.URL;
import java.net.http.HttpClient;
import java.net.http.HttpRequest;
import java.net.http.HttpResponse;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.time.Duration;
import java.util.Map;
import java.util.UUID;


    /* Create a presigned URL to use in a subsequent PUT request */
    public String createPresignedUrl(String bucketName, String keyName, Map<String, String> metadata) {
        try (S3Presigner presigner = S3Presigner.create()) {

            PutObjectRequest objectRequest = PutObjectRequest.builder()
                    .bucket(bucketName)
                    .key(keyName)
                    .metadata(metadata)
                    .build();

            PutObjectPresignRequest presignRequest = PutObjectPresignRequest.builder()
                    .signatureDuration(Duration.ofMinutes(10))  // The URL expires in 10 minutes.
                    .putObjectRequest(objectRequest)
                    .build();


            PresignedPutObjectRequest presignedRequest = presigner.presignPutObject(presignRequest);
            String myURL = presignedRequest.url().toString();
            logger.info("Presigned URL to upload a file to: [{}]", myURL);
            logger.info("HTTP method: [{}]", presignedRequest.httpRequest().method());

            return presignedRequest.url().toExternalForm();
        }
    }

Parte 2: carica un oggetto file

Bob utilizza una delle seguenti tre opzioni di codice per caricare un file.


    /* Use the JDK HttpURLConnection (since v1.1) class to do the upload. */
    public void useHttpUrlConnectionToPut(String presignedUrlString, File fileToPut, Map<String, String> metadata) {
        logger.info("Begin [{}] upload", fileToPut.toString());
        try {
            URL presignedUrl = new URL(presignedUrlString);
            HttpURLConnection connection = (HttpURLConnection) presignedUrl.openConnection();
            connection.setDoOutput(true);
            metadata.forEach((k, v) -> connection.setRequestProperty("x-amz-meta-" + k, v));
            connection.setRequestMethod("PUT");
            OutputStream out = connection.getOutputStream();

            try (RandomAccessFile file = new RandomAccessFile(fileToPut, "r");
                 FileChannel inChannel = file.getChannel()) {
                ByteBuffer buffer = ByteBuffer.allocate(8192); //Buffer size is 8k

                while (inChannel.read(buffer) > 0) {
                    buffer.flip();
                    for (int i = 0; i < buffer.limit(); i++) {
                        out.write(buffer.get());
                    }
                    buffer.clear();
                }
            } catch (IOException e) {
                logger.error(e.getMessage(), e);
            }

            out.close();
            connection.getResponseCode();
            logger.info("HTTP response code is " + connection.getResponseCode());

        } catch (S3Exception | IOException e) {
            logger.error(e.getMessage(), e);
        }
    }


    /* Use the JDK HttpClient (since v11) class to do the upload. */
    public void useHttpClientToPut(String presignedUrlString, File fileToPut, Map<String, String> metadata) {
        logger.info("Begin [{}] upload", fileToPut.toString());

        HttpRequest.Builder requestBuilder = HttpRequest.newBuilder();
        metadata.forEach((k, v) -> requestBuilder.header("x-amz-meta-" + k, v));

        HttpClient httpClient = HttpClient.newHttpClient();
        try {
            final HttpResponse<Void> response = httpClient.send(requestBuilder
                            .uri(new URL(presignedUrlString).toURI())
                            .PUT(HttpRequest.BodyPublishers.ofFile(Path.of(fileToPut.toURI())))
                            .build(),
                    HttpResponse.BodyHandlers.discarding());

            logger.info("HTTP response code is " + response.statusCode());

        } catch (URISyntaxException | InterruptedException | IOException e) {
            logger.error(e.getMessage(), e);
        }
    }


    /* Use the AWS SDK for Java V2 SdkHttpClient class to do the upload. */
    public void useSdkHttpClientToPut(String presignedUrlString, File fileToPut, Map<String, String> metadata) {
        logger.info("Begin [{}] upload", fileToPut.toString());

        try {
            URL presignedUrl = new URL(presignedUrlString);

            SdkHttpRequest.Builder requestBuilder = SdkHttpRequest.builder()
                    .method(SdkHttpMethod.PUT)
                    .uri(presignedUrl.toURI());
            // Add headers
            metadata.forEach((k, v) -> requestBuilder.putHeader("x-amz-meta-" + k, v));
            // Finish building the request.
            SdkHttpRequest request = requestBuilder.build();

            HttpExecuteRequest executeRequest = HttpExecuteRequest.builder()
                    .request(request)
                    .contentStreamProvider(new FileContentStreamProvider(fileToPut.toPath()))
                    .build();

            try (SdkHttpClient sdkHttpClient = ApacheHttpClient.create()) {
                HttpExecuteResponse response = sdkHttpClient.prepareRequest(executeRequest).call();
                logger.info("Response code: {}", response.httpResponse().statusCode());
            }
        } catch (URISyntaxException | IOException e) {
            logger.error(e.getMessage(), e);
        }
    }

Guarda l'esempio completo e prosegui il test. GitHub

Avvertimento JavaScript è disabilitato o non è disponibile nel tuo browser.

Per usare la documentazione AWS, JavaScript deve essere abilitato. Consulta le pagine della guida del browser per le istruzioni.

Convenzioni dei documenti

Operazioni sugli oggetti

Accesso interregionale