Kod do postu o Google Cloud Storage znajdujący się pod adresem https://blog.mloza.pl/google-cloud-storage/

CredentialsProvider.java

public class CredentialsProvider {
    public static Credential authorize() {
        try {
            return GoogleCredential.fromStream(CredentialsProvider.class.getClassLoader()
                                               .getResourceAsStream("client-secrets.json"))
                    .createScoped(Collections.singleton(StorageScopes.CLOUD_PLATFORM));
        } catch (IOException e) {
            Throwables.propagate(e);
        }
        return null;
    }
}

deleteObjectFromBucket.java

    @Test
    public void deleteObjectFromBucket() throws Exception {
        storage.objects()
                .delete("blog-test", "kot-z-serem-x2.jpg")
                .execute();

        listBucket();
    }

getObjectFromBucket.java

    @Test
    public void getObjectFromBucket() throws Exception {
        storage.objects()
                .get("blog-test", "kot-z-serem.jpg") //1
                .executeMediaAndDownloadTo(new FileOutputStream("kot-z-serem.jpg")); //2
    }

GoogleCloudStorageTest.java

public class GoogleCloudStorageTest {
    private static final String APPLICATION_NAME = "Test Application";

    private HttpTransport httpTransport;
    private Credential credential;
    private JsonFactory jsonFactory;
    private Storage storage;

    @BeforeClass
    public void setUp() throws Exception {
        try {
            httpTransport = GoogleNetHttpTransport.newTrustedTransport();
            credential = CredentialsProvider.authorize();
            jsonFactory = new JacksonFactory();
            storage = new Storage.Builder(httpTransport, jsonFactory, credential).setApplicationName(APPLICATION_NAME).build();
        } catch (GeneralSecurityException | IOException e) {
            e.printStackTrace();
        }
    }

    @Test
    public void listBuckets() throws Exception {
        storage.buckets()
                .list("test-ocr-on-googl")
                .execute()
                .getItems()
                .forEach(i -> System.out.println(i.getName()));
    }
}

listBucket.java

    @Test
    public void listBucket() throws Exception {
        storage.objects()
                .list("blog-test") // 1
                .execute()
                .getItems()
                .forEach(i -> System.out.println(i.getName()));
    }

listBucketWithPrefix.java

    @Test
    public void listBucketWithPrefix() throws Exception {
        storage.objects()
                .list("blog-test")
                .setPrefix("fol") // 1
                .execute()
                .getItems()
                .forEach(i -> System.out.println(i.getName()));
    }

Main.java

public class Main {
    public static void main(String[] args) {
        try {
            HttpTransport httpTransport = GoogleNetHttpTransport.newTrustedTransport();
            JsonFactory jsonFactory = new JacksonFactory();
            Credential credential = GoogleCredential
                    .fromStream(
                            Main.class.getClassLoader()
                                    .getResourceAsStream("client-secrets.json")) // 1
                    .createScoped(Collections.singleton(StorageScopes.CLOUD_PLATFORM)); // 2

            Storage storage = new Storage.Builder(httpTransport, jsonFactory, credential)
                    .setApplicationName("Test project")  // 3
                    .build();

            storage.buckets()
                    .list("blog-test")
                    .execute()
                    .getItems()
                    .forEach(i -> System.out.println(i.getName())); // 4
        } catch (GeneralSecurityException | IOException e) {
            e.printStackTrace();
        }
    }
}

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>pl.mloza</groupId>
    <artifactId>google-cloud-storage</artifactId>
    <version>1.0-SNAPSHOT</version>

    <dependencies>
        <dependency>
            <groupId>com.google.apis</groupId>
            <artifactId>google-api-services-storage</artifactId>
            <version>v1-rev72-1.22.0</version>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <configuration>
                    <source>1.8</source>
                    <target>1.8</target>
                </configuration>
            </plugin>
        </plugins>
    </build>
</project>

uploadObjectToBucket.java

    @Test
    public void uploadObjectToBucket() throws Exception {
        InputStreamContent mediaContent = new InputStreamContent("image/jpeg", new FileInputStream("kot-z-serem-x.jpg")); // 1
        storage.objects()
                .insert("blog-test", null, mediaContent) // 2
                .setName("kot-z-serem-x.jpg") // 3
                .execute();

        listBucket(); //4
    }