Java Examples

The examples provided show the code for connecting and the following operations:

• list buckets
• create a bucket
• delete a bucket
• verify that a bucket exists
• list files
• upload a file
• delete a file
• verify that a file exists

The examples have the following dependency:

com.amazonaws:aws-java-sdk-s3:1.11.754

package org.example.objectstore;

import com.amazonaws.auth.AWSCredentials;
import com.amazonaws.auth.BasicAWSCredentials;
import com.amazonaws.services.s3.AmazonS3;

public class Objectstore {
    private static final String USERNAME = "minioadmin";
    private static final String PASSWORD = "minioadmin";
    private static final String URL = "http://localhost:9000";
    private static final String BUCKET_NAME = "test";
    private static final String FILE_NAME = "file";

    public static void main(String[] args) {
        AWSCredentials credentials = new BasicAWSCredentials(USERNAME, PASSWORD);
        AmazonS3 s3 = Operations.getConnection(URL, credentials, true);

        Operations.demo(s3, BUCKET_NAME, FILE_NAME);
    }
}

package org.example.objectstore;

import com.amazonaws.ClientConfiguration;
import com.amazonaws.SDKGlobalConfiguration;
import com.amazonaws.auth.AWSCredentials;
import com.amazonaws.auth.AWSStaticCredentialsProvider;
import com.amazonaws.client.builder.AwsClientBuilder;
import com.amazonaws.regions.Regions;
import com.amazonaws.services.s3.AmazonS3;
import com.amazonaws.services.s3.AmazonS3ClientBuilder;
import com.amazonaws.services.s3.model.Bucket;
import com.amazonaws.services.s3.model.ObjectListing;
import com.amazonaws.services.s3.model.ObjectMetadata;
import com.amazonaws.services.s3.model.PutObjectRequest;
import com.amazonaws.services.s3.model.S3Object;
import com.amazonaws.services.s3.model.S3ObjectSummary;

import java.io.BufferedReader;
import java.io.ByteArrayInputStream;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.nio.charset.StandardCharsets;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.List;
import java.util.stream.Collectors;

public class Operations {
    private static final String S3_SIGNER = "S3SignerType";
    private static final String S3_V4_SIGNER = "AWSS3V4SignerType";

    public static AmazonS3 getConnection(String url, AWSCredentials credentials, boolean isS3v4) {
        final ClientConfiguration clientConfiguration = new ClientConfiguration();
        clientConfiguration.setSignerOverride(isS3v4 ? S3_V4_SIGNER : S3_SIGNER);

        System.setProperty(SDKGlobalConfiguration.DISABLE_CERT_CHECKING_SYSTEM_PROPERTY, "true");

        return AmazonS3ClientBuilder
            .standard()
            .withEndpointConfiguration(new AwsClientBuilder.EndpointConfiguration(url, Regions.US_EAST_1.name()))
            .withPathStyleAccessEnabled(true)
            .withClientConfiguration(clientConfiguration)
            .withCredentials(new AWSStaticCredentialsProvider(credentials))
            .build();
    }

    public static void demo(AmazonS3 s3, String bucketName, String file) {
        System.out.println();
        Operations.listBuckets(s3);

        System.out.println();
        Operations.createBucketIfNotExists(s3, bucketName);
        Operations.listBuckets(s3);

        System.out.println();
        Operations.uploadFileIfNotExists(s3, bucketName, file);
        Operations.listFolder(s3, bucketName);

        System.out.println();
        Operations.readFile(s3, bucketName, file);

        System.out.println();
        Operations.clearBucket(s3, bucketName);
        Operations.listFolder(s3, bucketName);

        System.out.println();
        Operations.deleteBucketIfExists(s3, bucketName);
        Operations.listBuckets(s3);
    }

    public static void listBuckets(AmazonS3 s3) {
        List < Bucket > buckets = s3.listBuckets();
        System.out.println("Buckets:");
        buckets.stream().map(Bucket::getName).forEach(System.out::println);
    }

    public static boolean checkIfBucketExists(AmazonS3 s3, String bucketName) {
        System.out.println("Checking if bucket '" + bucketName + "' exists...");
        return s3.doesBucketExistV2(bucketName);
    }

    public static void createBucketIfNotExists(AmazonS3 s3, String bucketName) {
        if (checkIfBucketExists(s3, bucketName)) {
            System.out.println("Bucket '" + bucketName + "' exists");
            return;
        }

        System.out.println("Creating bucket '" + bucketName + "' ...");
        s3.createBucket(bucketName);
    }

    public static void deleteBucketIfExists(AmazonS3 s3, String bucketName) {
        if (!checkIfBucketExists(s3, bucketName)) {
            System.out.println("Bucket '" + bucketName + "' not exists");
            return;
        }

        System.out.println("Deleting bucket '" + bucketName + "' ...");
        s3.deleteBucket(bucketName);
    }

    public static boolean checkIfFileExists(AmazonS3 s3, String bucketName, String file) {
        System.out.println("Checking if file '" + file + "' exists in bucket '" + bucketName + "'");
        return s3.doesObjectExist(bucketName, file);
    }

    public static void uploadFileIfNotExists(AmazonS3 s3, String bucketName, String file) {
        if (checkIfFileExists(s3, bucketName, file)) {
            System.out.println("File '" + file + "' exists in bucket '" + bucketName + "'");
            return;
        }

        SimpleDateFormat formatter = new SimpleDateFormat("MM/dd/yyyy 'at' HH:mm:ss");
        Date date = new Date(System.currentTimeMillis());
        String data = "Hello world on " + formatter.format(date) + "!";
        System.out.println("Uploading '" + file + "' to '" + bucketName + "' with data:\n" + data + "\n");

        ObjectMetadata metadata = new ObjectMetadata();
        metadata.setContentType("plain/text");

        InputStream dataStream = new ByteArrayInputStream(data.getBytes());
        PutObjectRequest request = new PutObjectRequest(bucketName, file, dataStream, metadata);

        s3.putObject(request);
    }

    public static void listFolder(AmazonS3 s3, String bucketName) {
        System.out.println("Listing bucket '" + bucketName + "':");
        ObjectListing listing = s3.listObjects(bucketName);
        listing.getObjectSummaries()
            .stream()
            .map(S3ObjectSummary::getKey)
            .forEach(System.out::println);
    }

    public static void clearBucket(AmazonS3 s3, String bucketName) {
        System.out.println("Cleaning all from bucket '" + bucketName + "'..");
        ObjectListing listing = s3.listObjects(bucketName);
        listing.getObjectSummaries()
            .stream()
            .map(S3ObjectSummary::getKey)
            .forEach(file - > s3.deleteObject(bucketName, file));
    }

    public static void readFile(AmazonS3 s3, String bucketName, String file) {
        System.out.println("Reading file '" + file + "' from bucket '" + bucketName + "'");
        S3Object object = s3.getObject(bucketName, file);
        String data = new BufferedReader(new InputStreamReader(object.getObjectContent(), StandardCharsets.UTF_8))
            .lines()
            .collect(Collectors.joining("\n"));
        System.out.println("Data:\n" + data);
    }
}