使用akka-stream-alpakka从s3下载pdf文件

<dependency>
    <groupId>com.lightbend.akka</groupId>
    <artifactId>akka-stream-alpakka-s3_2.13</artifactId>
    <version>2.2.0</version>
</dependency>

import software.amazon.awssdk.auth.credentials.DefaultCredentialsProvider;
import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.s3.S3Client;

S3Client s3Client = S3Client.builder()
        .region(Region.US_EAST_1)
        .credentialsProvider(DefaultCredentialsProvider.create())
        .build();

import akka.actor.ActorSystem;
import akka.stream.ActorMaterializer;
import akka.stream.alpakka.s3.S3Settings;
import akka.stream.alpakka.s3.javadsl.S3;
import akka.stream.javadsl.FileIO;
import akka.stream.javadsl.Sink;
import akka.stream.javadsl.Source;
import akka.util.ByteString;
import software.amazon.awssdk.services.s3.model.GetObjectRequest;

ActorSystem system = ActorSystem.create();
ActorMaterializer materializer = ActorMaterializer.create(system);

S3Settings settings = S3Settings.create(system);
String bucket = "your-bucket-name";
String key = "your-pdf-file-key";

Source<ByteString, CompletionStage<IOResult>> s3Source = S3.download(bucket, key)
        .withAttributes(S3Attributes.settings(settings))
        .withAttributes(S3Attributes.bufferType(MemoryBufferType.getInstance()));

Sink<ByteString, CompletionStage<IOResult>> fileSink = FileIO.toPath(Paths.get("path/to/save/file.pdf"));

CompletionStage<IOResult> downloadResult = s3Source.runWith(fileSink, materializer);
downloadResult.thenAccept(result -> {
    if (result.wasSuccessful()) {
        System.out.println("PDF file downloaded successfully.");
    } else {
        System.out.println("Failed to download PDF file: " + result.getError());
    }
});