如何从 Amazon S3 存储桶内的文件夹中获取 PDF 文件

Question

我是 AWS 和 S3 with Java 的新手，我想从 s3 存储桶中获取一个对象，该对象是存储桶中文件夹内的 pdf 文件。我已成功从 s3 存储桶获取文件，但在尝试从文件夹获取文件时遇到文件未找到异常。

这是我的代码 -

 public static void main(String[] args) {
        System.out.println("Fetching pdf from aws s3");

        String bucket = "my-bucket";
        String key = "65/65-abc.pdf";
        AmazonS3 amazonS3 = getAmazonS3Client();

        S3Object object = amazonS3.getObject(new GetObjectRequest(bucket, key));
        InputStream ins = object.getObjectContent();

        try {
            PDDocument doc = PDDocument.load(ins);
            //Saving the document
            doc.save(key);
            System.out.println("PDF created");
        }
        catch (Exception e){
            System.out.println(e);
        }

    }

    private static AmazonS3 getAmazonS3Client(){
        AWSCredentials awsCredentials = new BasicAWSCredentials("myAccessKey", "mySecretKey");
        return AmazonS3ClientBuilder.standard()
                .withCredentials(new AWSStaticCredentialsProvider(awsCredentials))
                .withRegion(Regions.US_EAST_2).build();
    }

输出 -

 java.io.FileNotFoundException: 65\65-abc.pdf (The system cannot find the path specified)

我的 S3 存储桶结构类似于 -

my-bucket/65/65-abc.pdf 

my-bucket = 是存储桶名称 65 = 是文件夹名称 65-abc.pdf = 是文件名

Answer 1

假设我在这样的文件夹中有一个 PDF：

我可以使用 传输管理器 - 适用于 Java V2 的 AWS 开发工具包。

您正在使用非常旧的 Java API，它不再被认为是最佳实践。亚马逊强烈建议使用 V2 而不是 V1。

现在这里是 代码 适合此用例。

package com.example.transfermanager;

import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.transfer.s3.FileDownload;
import software.amazon.awssdk.transfer.s3.S3TransferManager;
import java.nio.file.Paths;

/**
 * To run this AWS code example, ensure that you have setup your development environment, including your AWS credentials.
 *
 * For information, see this documentation topic:
 *
 * https://docs.aws.amazon.com/sdk-for-java/latest/developer-guide/get-started.html
 */
public class GetObject {

    public static void main(String[] args) {

        final String usage = "\n" +
                "Usage:\n" +
                "  <bucketName> <objectKey> <objectPath> \n\n" +
                "Where:\n" +
                "  bucketName - the Amazon S3 bucket to upload an object into.\n" +
                "  objectKey - the object to download (for example, book.pdf).\n" +
                "  objectPath - the path where the file is written (for example, C:/AWS/book2.pdf). \n\n" ;

    

        long MB = 1024;
        String bucketName =  "<MyBucket>";  //args[0];
        String objectKey =  "foo/foo2/book.pdf" ; //args[1];
        String objectPath =  "C:/AWS/bookhuge39.pdf" ; //args[2];

        Region region = Region.US_EAST_1;
        S3TransferManager transferManager =  S3TransferManager.builder()
                .s3ClientConfiguration(cfg ->cfg.region(region)
                        .targetThroughputInGbps(20.0)
                        .minimumPartSizeInBytes(10 * MB))
                .build();

        downloadObjectTM(transferManager, bucketName,  objectKey, objectPath);
        System.out.println("Object was successfully downloaded using the Transfer Manager.");
        transferManager.close();
    }

    public static void downloadObjectTM(S3TransferManager transferManager, String  bucketName, String objectKey, String objectPath ) {
        FileDownload download =
                transferManager.downloadFile(d -> d.getObjectRequest(g -> g.bucket(bucketName).key(objectKey))
                        .destination(Paths.get(objectPath)));
        download.completionFuture().join();

    }
}