Save Image in Google Cloud Storage

I'm currently working on a project where we should have the possibility to upload files to the Google Cloud Storage. So we created an Bucket and I added the Maven dependency to my local "normal" application:

<dependencies>
    <dependency>
        <groupId>com.google.appengine.tools</groupId>
        <artifactId>appengine-gcs-client</artifactId>
        <version>RELEASE</version>
    </dependency>
</dependencies>

Then I started to read a local file and tried to push that to the Google Cloud Storage in a simply main:

try {
    final GcsService gcsService = GcsServiceFactory
        .createGcsService();

    File file = new File("/tmp/test.jpg");
    FileInputStream fis = new FileInputStream(file);
    GcsFilename fileName = new GcsFilename("test1213","test.jpg");
    GcsOutputChannel outputChannel;
    outputChannel = gcsService.createOrReplace(fileName, GcsFileOptions.getDefaultInstance());
    copy(fis, Channels.newOutputStream(outputChannel));
} catch (IOException e) {
    e.printStackTrace();
}

My copy method looks like this:

private static final int BUFFER_SIZE = 2 * 1024 * 1024;

private static void copy(InputStream input, OutputStream output)
        throws IOException {
    try {
        byte[] buffer = new byte[BUFFER_SIZE];
        int bytesRead = input.read(buffer);
        while (bytesRead != -1) {
            output.write(buffer, 0, bytesRead);
            bytesRead = input.read(buffer);
        }
    } finally {
        input.close();
        output.close();
    }
}

All I get from that is this:

The API package 'file' or call 'Create()' was not found.

After searching a lot in google, reading documentations even searching in bing i found this entry: The API package 'channel' or call 'CreateChannel()' was not found

It says that there is no way to use the appengine.tools -> gcs-client without such an AppEngine App. But is there an easy way to upload files to the Google Cloud Storage without to be forced on using the AppEngine service?

It sounds like you're not using App Engine. That's completely fine. Google Cloud Storage can work fine with App Engine, but it by no means requires it. The appengine-gcs-client package you're trying to use does require App Engine, though.

Instead, you want google-api-services-storage.

There's an example of using the GCS JSON API with Java and Maven here:

https://cloud.google.com/storage/docs/json_api/v1/json-api-java-samples