GetObject.java

// Copyright 2018 Amazon.com, Inc. or its affiliates. All Rights Reserved.
// SPDX-License-Identifier: MIT-0 (For details, see https://github.com/awsdocs/amazon-s3-developer-guide/blob/master/LICENSE-SAMPLECODE.)

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;

import com.amazonaws.AmazonServiceException;
import com.amazonaws.SdkClientException;
import com.amazonaws.auth.profile.ProfileCredentialsProvider;
import com.amazonaws.services.s3.AmazonS3;
import com.amazonaws.services.s3.AmazonS3ClientBuilder;
import com.amazonaws.services.s3.model.GetObjectRequest;
import com.amazonaws.services.s3.model.ResponseHeaderOverrides;
import com.amazonaws.services.s3.model.S3Object;

public class GetObject {

    public static void main(String[] args) throws IOException {
        String clientRegion = "*** Client region ***";
        String bucketName = "*** Bucket name ***";
        String key = "*** Object key ***";

        S3Object fullObject = null, objectPortion = null, headerOverrideObject = null;
        try {
            AmazonS3 s3Client = AmazonS3ClientBuilder.standard()
                    .withRegion(clientRegion)
                    .withCredentials(new ProfileCredentialsProvider())
                    .build();

            // Get an object and print its contents.
            System.out.println("Downloading an object");
            fullObject = s3Client.getObject(new GetObjectRequest(bucketName, key));
            System.out.println("Content-Type: " + fullObject.getObjectMetadata().getContentType());
            System.out.println("Content: ");
            displayTextInputStream(fullObject.getObjectContent());
            
            // Get a range of bytes from an object and print the bytes.
            GetObjectRequest rangeObjectRequest = new GetObjectRequest(bucketName, key)
                                                        .withRange(0,9);
            objectPortion = s3Client.getObject(rangeObjectRequest);
            System.out.println("Printing bytes retrieved.");
            displayTextInputStream(objectPortion.getObjectContent());
            
            // Get an entire object, overriding the specified response headers, and print the object's content.
            ResponseHeaderOverrides headerOverrides = new ResponseHeaderOverrides()
                                                            .withCacheControl("No-cache")
                                                            .withContentDisposition("attachment; filename=example.txt");
            GetObjectRequest getObjectRequestHeaderOverride = new GetObjectRequest(bucketName, key)
                                                            .withResponseHeaders(headerOverrides);
            headerOverrideObject = s3Client.getObject(getObjectRequestHeaderOverride);
            displayTextInputStream(headerOverrideObject.getObjectContent());
        }
        catch(AmazonServiceException e) {
            // The call was transmitted successfully, but Amazon S3 couldn't process 
            // it, so it returned an error response.
            e.printStackTrace();
        }
        catch(SdkClientException e) {
            // Amazon S3 couldn't be contacted for a response, or the client
            // couldn't parse the response from Amazon S3.
            e.printStackTrace();
        }
        finally {
            // To ensure that the network connection doesn't remain open, close any open input streams.
            if(fullObject != null) {
                fullObject.close();
            }
            if(objectPortion != null) {
                objectPortion.close();
            }
            if(headerOverrideObject != null) {
                headerOverrideObject.close();
            }
        }
    }

    private static void displayTextInputStream(InputStream input) throws IOException {
        // Read the text input stream one line at a time and display each line.
        BufferedReader reader = new BufferedReader(new InputStreamReader(input));
        String line = null;
        while ((line = reader.readLine()) != null) {
            System.out.println(line);
        }
        System.out.println();
    }
}