# Java quickstart for customers using a service account

Follow the steps in this quickstart guide, and in about 10 minutes you have
a simple Java command-line app that makes requests to the zero-touch
enrollment customer API using a service account.

## Prerequisites

To run this quickstart, you need:

- A service account, that's linked to you zero-touch enrollment customer account. See [Get
  started](https://developers.google.com/zero-touch/guides/customer/service-accounts).
- Java 1.7 or greater.
- [Gradle 2.3 or greater](http://gradle.org/downloads).
- Access to the internet and a web browser.

## Step 1: Turn on the zero-touch enrollment API

1. Use [this
   wizard](https://console.developers.google.com/start/api?id=androiddeviceprovisioning.googleapis.com) to create or select a project in the Google Developers Console and automatically turn on the API. Click **Continue** , then **Go to credentials**.
2. Set **What data will you be accessing?** to *Application data*.
3. Click **Next**. You should be prompted to create a service account.
4. Give a descriptive name for **Service account name**.
5. Note the **Service account ID** (it looks like an email address) because you'll use it later.
6. Set **Role** to *Service Accounts \> Service Account User*.
7. Click **Done** to finish creating the service account.
8. Click the email address for the service account that you created.
9. Click \*\*Keys\*\*.
10. Click \*\*Add key\*\*, then click \*\*Create new key\*\*.
11. For \*\*Key type\*\*, select \*\*JSON\*\*.
12. Click **Create** and the private key downloads to your computer.
13. Click \*\*Close\*\*.
14. Move the file to your working directory and rename it `service_account_key.json`.

> [!WARNING]
> **Warning:** Service account keys can become a security risk if not managed carefully. For advice see [best practices for managing API keys](https://cloud.google.com/iam/docs/best-practices-for-managing-service-account-keys).

## Step 2: Prepare the project

Follow the steps below to set up your Gradle project:

1. Run the following command to create a new project in the working directory:

       gradle init --type basic
       mkdir -p src/main/java src/main/resources

2. Copy the `service_account_key.json` you downloaded when you created your
   service account into the `src/main/resources/` directory you created above.

3. Open the default `build.gradle` file and replace its contents with the
   following code:

```
apply plugin: 'java'
apply plugin: 'application'

mainClassName = 'CustomerQuickstart'
sourceCompatibility = 1.7
targetCompatibility = 1.7
version = '1.0'

repositories {
    mavenCentral()
}

dependencies {
    compile 'com.google.api-client:google-api-client:2.2.0'
    compile 'com.google.apis:google-api-services-androiddeviceprovisioning:v1-rev20230509-2.0.0'
    compile 'com.google.auth:google-auth-library-oauth2-http:1.16.1'
    compile 'com.google.auth:google-auth-library-credentials:1.16.1'
    compile 'com.google.http-client:google-http-client:1.43.1'
    compile 'com.google.oauth-client:google-oauth-client-jetty:1.34.1'
}
```

## Step 3: Set up the sample

Create a file named `src/main/java/CustomerQuickstart.java` and copy in the
following code and save the file.

```java
import com.google.api.client.googleapis.javanet.GoogleNetHttpTransport;
import com.google.api.client.http.HttpRequestInitializer;
import com.google.api.client.http.HttpTransport;
import com.google.api.client.json.JsonFactory;
import com.google.api.client.json.gson.GsonFactory;
import com.google.api.services.androiddeviceprovisioning.v1.AndroidProvisioningPartner;
import com.google.api.services.androiddeviceprovisioning.v1.model.Company;
import com.google.api.services.androiddeviceprovisioning.v1.model.CustomerListCustomersResponse;
import com.google.api.services.androiddeviceprovisioning.v1.model.CustomerListDpcsResponse;
import com.google.api.services.androiddeviceprovisioning.v1.model.Dpc;
import com.google.auth.http.HttpCredentialsAdapter;
import com.google.auth.oauth2.GoogleCredentials;
import com.google.auth.oauth2.ServiceAccountCredentials;
import java.io.IOException;
import java.io.InputStream;
import java.util.Arrays;
import java.util.List;

/** This class forms the quickstart introduction to the zero-touch enrollment customer API. */
public class CustomerQuickstart {

  // A single auth scope is used for the zero-touch enrollment customer API.
  private static final List<String> SCOPES =
      Arrays.asList("https://www.googleapis.com/auth/androidworkzerotouchemm");
  private static final String APP_NAME = "Zero-touch Enrollment Java Quickstart";

  // Global shared instances
  private static final JsonFactory JSON_FACTORY = GsonFactory.getDefaultInstance();
  private static HttpTransport HTTP_TRANSPORT;

  static {
    try {
      HTTP_TRANSPORT = GoogleNetHttpTransport.newTrustedTransport();
    } catch (Throwable t) {
      t.printStackTrace();
      System.exit(1);
    }
  }

  /**
   * Creates a GoogleCredentials object with the correct OAuth2 authorization for the service
   * account that calls the reseller API. The service endpoint invokes this method when setting up a
   * new service instance.
   *
   * @return an authorized GoogleCredentials object.
   * @throws IOException
   */
  public static GoogleCredentials authorize() throws IOException {
    // Load service account key.
    InputStream in = CustomerQuickstart.class.getResourceAsStream("/service_account_key.json");

    // Create the credential scoped to the zero-touch enrollment customer APIs.
    GoogleCredentials credential = ServiceAccountCredentials.fromStream(in).createScoped(SCOPES);
    return credential;
  }

  /**
   * Build and return an authorized zero-touch enrollment API client service. Use the service
   * endpoint to call the API methods.
   *
   * @return an authorized client service endpoint
   * @throws IOException
   */
  public static AndroidProvisioningPartner getService() throws IOException {
    GoogleCredentials credential = authorize();
    HttpRequestInitializer requestInitializer = new HttpCredentialsAdapter(credential);
    return new AndroidProvisioningPartner.Builder(HTTP_TRANSPORT, JSON_FACTORY, requestInitializer)
        .setApplicationName(APP_NAME)
        .build();
  }

  /**
   * Runs the zero-touch enrollment quickstart app.
   *
   * @throws IOException
   */
  public static void main(String[] args) throws IOException {

    // Create a zero-touch enrollment API service endpoint.
    AndroidProvisioningPartner service = getService();

    // Get the customer's account. Because a customer might have more
    // than one, limit the results to the first account found.
    AndroidProvisioningPartner.Customers.List accountRequest = service.customers().list();
    accountRequest.setPageSize(1);
    CustomerListCustomersResponse accountResponse = accountRequest.execute();
    if (accountResponse.getCustomers().isEmpty()) {
      // No accounts found for the user. Confirm the Google Account
      // that authorizes the request can access the zero-touch portal.
      System.out.println("No zero-touch enrollment account found.");
      System.exit(-1);
    }
    Company customer = accountResponse.getCustomers().get(0);
    String customerAccount = customer.getName();

    // Send an API request to list all the DPCs available using the customer account.
    AndroidProvisioningPartner.Customers.Dpcs.List request =
        service.customers().dpcs().list(customerAccount);
    CustomerListDpcsResponse response = request.execute();

    // Print out the details of each DPC.
    java.util.List<Dpc> dpcs = response.getDpcs();
    for (Dpc dpcApp : dpcs) {
      System.out.format("Name:%s  APK:%s\n", dpcApp.getDpcName(), dpcApp.getPackageName());
    }
  }
}
```

## Step 4: Run the sample

Use your operating system's help to run the script in the file. On UNIX and Mac
computers, run the command below in your terminal:

    gradle -q run

## Notes

- Avoid sharing your `service_account_key.json` file with anyone. Be careful not to include it in source code repositories. You can read more advice on [handling service account secrets](https://cloud.google.com/iam/docs/best-practices-for-managing-service-account-keys).

## Learn more

- [Google Developers Console help documentation](https://developers.google.com/console/help/new)
- [Google APIs Client for Java documentation](https://developers.google.com/api-client-library/java)
- [Google APIs Client Javadocs](https://developers.google.com/api-client-library/java/google-api-java-client/reference)