How to correctly load Firebase ServiceAccount json resource with Spring MVC? - json

Question

I'm trying to connect my Spring MVC (not Spring Boot) application to Firebase. My application's folder structure looks like this:
folder structure
The problem is that I don't know where to place the api key json file, how to load the resource, and the correct order of the method calls.
I tried loading the resource the way shown below. Before that I also tried using ClassLoader to load it from the WEB-INF folder and it worked, but changed the code and kept receiving NullPointer Exception (why not FileNotFound Exception?) for the InputStream and couldn't restore the previous state.
With the current state I keep receiving FileNotFound Exception as I'm am not able to load the resource no matter how much I googled "Spring MVC load resource" and as I checked the debugger the service account's "init" method with #PostConstruct isn't running at starting the server.
I understand that I should be able to load the resource and call the "init" method in order to make it work. (I suppose it's enough to call it once after creating the bean and before using firebase methods) But I just couldn't come up with a working implementation.
I used examples from here:
https://github.com/savicprvoslav/Spring-Boot-starter
(Bottom of the Page)
My Controller Class:
#Controller
#RequestMapping("/firebase")
public class FirebaseController {
#Autowired
private FirebaseService firebaseService;
#GetMapping(value="/upload/maincategories")
public void uploadMainRecordCategories() {
firebaseService.uploadMainRecordCategories();
}
My Service Class:
#Service
public class FirebaseServiceBean implements FirebaseService {
#Value("/api.json")
Resource apiKey;
#Override
public void uploadMainRecordCategories() {
// do something
}
#PostConstruct
public void init() {
try (InputStream serviceAccount = apiKey.getInputStream()) {
FirebaseOptions options = new FirebaseOptions.Builder()
.setCredentials(GoogleCredentials.fromStream(serviceAccount))
.setDatabaseUrl(FirebaseStringValue.DB_URL).build();
FirebaseApp.initializeApp(options);
} catch (IOException e) {
e.printStackTrace();
}
}
}

Answer 1

how about saving value in a spring property and using #Value("${firebase.apiKey}")?
Alternatively, save path to file in property and reference that in #Value()
#Value("${service.account.path}")
private String serviceAccountPath;
In application.properties:
service.account.path = /path/to/service-account.json
then config code:
private String getAccessToken() throws IOException {
GoogleCredential googleCredential = GoogleCredential
.fromStream(getServiceAccountInputStream())
.createScoped(Collections.singletonList("https://www.googleapis.com/auth/firebase.messaging"));
googleCredential.refreshToken();
return googleCredential.getAccessToken();
}
private InputStream getServiceAccountInputStream() {
File file = new File(serviceAccountPath);
try {
return new FileInputStream(file);
} catch (FileNotFoundException e) {
throw new RuntimeException("Couldn't find service-account.json");
}
}