code snippet that shows the Login API

LoginAPI.java

// Download API Client and add to your project: 
// https://github.com/docusign/docuSign-java-client
import com.docusign.esign.api.*;
import com.docusign.esign.client.*;
import com.docusign.esign.model.*;

// Enter your DocuSign credentials
String UserName = "[EMAIL]";
String Password = "[PASSWORD]";    
String IntegratorKey = "[INTEGRATOR_KEY]";

// for production environment update to "www.docusign.net/restapi"
String BaseUrl = "https://demo.docusign.net/restapi";

// initialize the api client for the desired environment
ApiClient apiClient = new ApiClient();
apiClient.setBasePath(BaseUrl);

// create JSON formatted auth header
String creds = "{\"Username\":\"" +  UserName + "\",\"Password\":\"" +  Password + "\",\"IntegratorKey\":\"" +  IntegratorKey + "\"}";
apiClient.addDefaultHeader("X-DocuSign-Authentication", creds);

// assign api client to the Configuration object
Configuration.setDefaultApiClient(apiClient);

try
{
	// login call available off the AuthenticationApi
	AuthenticationApi authApi = new AuthenticationApi();

	// login has some optional parameters we can set
	AuthenticationApi.LoginOptions loginOps = authApi.new LoginOptions();
	loginOps.setApiPassword("true");
	loginOps.setIncludeAccountIdGuid("true");
	LoginInformation loginInfo = authApi.login(loginOps);

	// note that a given user may be a member of multiple accounts
	List<LoginAccount> loginAccounts = loginInfo.getLoginAccounts();

	System.out.println("LoginInformation: " + loginAccounts);
}
catch (com.docusign.esign.client.ApiException ex)
{
	System.out.println("Exception: " + ex);
}