如何使用 Java 读取 AWS S3 文件？

java amazon-s3 amazon-web-services

2022-09-01 12:26:31

我尝试将文件从 AWS S3 读取到我的 Java 代码中：

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

然后我得到了一个错误：

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

有没有办法从AWS S3打开/读取文件？多谢！

答案 1

Java 中的 “File” 类不理解 S3 的存在。下面是从 AWS 文档中读取文件的示例：

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

答案 2

在2019年，有一种更优化的方式可以从S3读取文件：

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();
    }
}