Read AWS s3 File to Java code

问题:

I tried to read a file from AWS s3 to my java code:

  File file = new File("s3n://mybucket/myfile.txt");
  FileInputStream fileInput = new FileInputStream(file);

Then I got an error:

java.io.FileNotFoundException: s3n:/mybucket/myfile.txt (No such file or directory) at java.io.FileInputStream.open(Native Method) at java.io.FileInputStream.(FileInputStream.java:146)

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Is there a way to open/read a file from AWS s3? Thanks a lot!

回答1:

The 'File' class from Java doesn't understand that S3 exists. Here's an example of reading a file from the AWS documentation:

AmazonS3 s3Client = new AmazonS3Client(new ProfileCredentialsProvider());        
S3Object object = s3Client.getObject(new GetObjectRequest(bucketName, key));
InputStream objectData = object.getObjectContent();
// Process the objectData stream.
objectData.close();

回答2:

In 2019 there's a bit more optimal way to read the file from S3:

private final AmazonS3 amazonS3Client = AmazonS3ClientBuilder.standard().build();

private Collection<String> loadFileFromS3() {
    try (final S3Object s3Object = amazonS3Client.getObject(BUCKET_NAME,
                                                            FILE_NAME);
         final InputStreamReader streamReader = new InputStreamReader(s3Object.getObjectContent(), StandardCharsets.UTF_8);
         final BufferedReader reader = new BufferedReader(streamReader)) {
        return reader.lines().collect(Collectors.toSet());
    } catch (final IOException e) {
        log.error(e.getMessage(), e)
        return Collections.emptySet();
    }
}