AWS SDK - Java

Please read the following to understand how to use the AWS SDK - Java with the 4EVERLAND Bucket. Combine the AWS SDK API for the Java language with the 4EVERLAND Bucket to achieve file uploads to the IPFS or Arweave storage networks.

Preparation

• In your development environment, download and install Java.

• Download and install the AWS SDK for Java.

• Register a free 4EVERLAND account.

• If you need to use Arweave storage, you need to create an Arweave bucket. Click to learn more.

• To obtain the corresponding API key in the bucket, click to learn more.

Development Examples

Create a bucket

bucketName: The desired bucket name to create

accessKey: Bucket-Access Keys-API key

secretKey: Bucket-Access Keys-API Secret

endpoint_url: https://endpoint.4everland.co

region: Default filled in with "4everland"

import com.amazonaws.AmazonServiceException;
import com.amazonaws.SdkClientException;
import com.amazonaws.auth.profile.ProfileCredentialsProvider;
import com.amazonaws.regions.Regions;
import com.amazonaws.services.s3.AmazonS3;
import com.amazonaws.services.s3.AmazonS3ClientBuilder;
import com.amazonaws.services.s3.model.CreateBucketRequest;
import com.amazonaws.services.s3.model.GetBucketLocationRequest;

import java.io.IOException;

public class CreateBucket2 {

    public static void main(String[] args) throws IOException {
        String bucketName = "new-bucketname";
        String accessKey = "4EVERLAND-Bucket-APIKey";
        String secretKey = "4EVERLAND-Bucket-APISecret";
        String endpoint_url = "https://endpoint.4everland.co";
        String region = "4everland";
        try {
            AmazonS3ClientBuilder.standard();
            AWSCredentials credentials = new BasicAWSCredentials(accessKey,secretKey);
            AmazonS3 s3Client = AmazonS3ClientBuilder.standard()
                    .withCredentials(credentials)
                    .withEndpointConfiguration(new AwsClientBuilder.EndpointConfiguration(endpoint_url, region))
                    .build();

            if (!s3Client.doesBucketExistV2(bucketName)) {
                s3Client.createBucket(new CreateBucketRequest(bucketName));

                String bucketLocation = s3Client.getBucketLocation(new GetBucketLocationRequest(bucketName));
                System.out.println("Bucket location: " + bucketLocation);
            }
        } catch (AmazonServiceException e) {
            e.printStackTrace();
        } catch (SdkClientException e) {
            e.printStackTrace();
        }
    }
}

Upload a file

bucketName: Your bucket name

stringObjKeyName: The name of the file to be uploaded

fileObjKeyName: The name of the file to be uploaded

fileName: The path of the file to be uploaded

accessKey: Bucket-Access Keys-API key

secretKey: Bucket-Access Keys-API Secret

endpoint_url: https://endpoint.4everland.co

region: Default filled in with "4everland"

import com.amazonaws.AmazonServiceException;
import com.amazonaws.SdkClientException;
import com.amazonaws.regions.Regions;
import com.amazonaws.services.s3.AmazonS3;
import com.amazonaws.services.s3.AmazonS3ClientBuilder;
import com.amazonaws.services.s3.model.ObjectMetadata;
import com.amazonaws.services.s3.model.PutObjectRequest;

import java.io.File;
import java.io.IOException;

public class UploadObject {

    public static void main(String[] args) throws IOException {
        String bucketName = "4everland-bucketname";
        String stringObjKeyName = "object-name";
        String fileObjKeyName = "object-name";
        String fileName = "/path/to/4everland/4ever.png";
        String accessKey = "4EVERLAND-Bucket-APIKey";
        String secretKey = "4EVERLAND-Bucket-APISecret";
        String endpoint_url = "https://endpoint.4everland.co";
        String region = "4everland";

        try {
            AWSCredentials credentials = new BasicAWSCredentials(accessKey,secretKey);
            AmazonS3 s3Client = AmazonS3ClientBuilder.standard()
                    .withCredentials(credentials)
                    .withEndpointConfiguration(new AwsClientBuilder.EndpointConfiguration(endpoint_url, region))
                    .build();

            s3Client.putObject(bucketName, stringObjKeyName, "Uploaded String Object");

            PutObjectRequest request = new PutObjectRequest(bucketName, fileObjKeyName, new File(fileName));
            ObjectMetadata metadata = new ObjectMetadata();
            metadata.setContentType("plain/text");
            metadata.addUserMetadata("title", "someTitle");
            request.setMetadata(metadata);
            s3Client.putObject(request);
        } catch (AmazonServiceException e) {

            e.printStackTrace();
        } catch (SdkClientException e) {
            e.printStackTrace();
        }
    }
}

Requesting IPFS CID and Arweave Hash

bucket: The bucket name where the target file is stored

key: The name of the target file

HeadObjectRequest headObjectRequest = HeadObjectRequest.builder()
  .bucket("4everland-bucketname")
  .key("your-object-name")
  .build();
  
HeadObjectResponse headObjectResponse = s3Client.headObject(headObjectRequest);
System.out.println("ipfs hash: " + headObjectResponse.metadata().get("ipfs-hash");
//If it is an Arweave type of bucket.
System.out.println("arweave hash: " + headObjectResponse.metadata().get("arweave-hash");

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