有没有办法使用Java从S3读取csv文件而不下载它

Question

我能够将 Java 连接到 AWS S3，并且能够执行基本操作，例如列出存储桶。我需要一种无需下载即可读取 CSV 文件的方法。我在这里附上我当前的代码。

import com.amazonaws.auth.AWSCredentials;
import com.amazonaws.auth.AWSStaticCredentialsProvider;
import com.amazonaws.auth.BasicAWSCredentials;
import com.amazonaws.regions.Regions;
import com.amazonaws.services.s3.AmazonS3;
import com.amazonaws.services.s3.AmazonS3Client;
import com.amazonaws.services.s3.AmazonS3ClientBuilder;
import com.amazonaws.services.s3.model.Bucket;
import com.amazonaws.services.s3.model.CannedAccessControlList;
import com.amazonaws.services.s3.model.ObjectMetadata;
import com.amazonaws.services.s3.model.PutObjectRequest;
import com.amazonaws.services.s3.model.S3ObjectSummary;

import java.io.IOException;
import java.io.InputStream;
import java.util.List;
import java.util.Properties;

public class test {

    public static void main(String args[])throws IOException
    {

        AWSCredentials credentials =new BasicAWSCredentials("----","----");

        AmazonS3 s3client = AmazonS3ClientBuilder
                .standard()
                .withCredentials(new AWSStaticCredentialsProvider(credentials))
                .withRegion(Regions.US_EAST_2)
                .build();

        List<Bucket> buckets = s3client.listBuckets();
        for(Bucket bucket : buckets) {
            System.out.println(bucket.getName());
        }
    }

}

Answer 1

为了让您的代码读取文件，它需要内容——这意味着将其复制到本地系统。

但是，您可以使用"range" (Java) 只读取一部分。

Answer 2

有一种方法可以使用这样的代码。在我的代码中，我试图在我的 S3Object obj 中获取我们想要读取的文件，然后将该文件传递给 InputStreamReader() ：

S3Object Obj = s3client.getObject("<Bucket Name>", "File Name");
BufferedReader reader = new BufferedReader(new InputStreamReader(Obj.getObjectContent()));

// this will store characters of first row in array    
String row[] = line.split(","); 
                                   
// this will fetch number of columns
int length = row.length;

while((line=reader.readLine()) != null) {

     // storing characters of corresponding line in an array
     String value[] = line.split(","); 
                                          
     for(int i=0;i<length;i++) {
         System.out.print(value[i]+"   ");
     }
     System.out.println();
}