How to avoid Google guice injector getInstance() repetative calls due to null?

问题

I have recently started using Google guice DI framework and am quite new to it. I am facing below problem - @inject returns null always and have to call injector to inject various references.

This is my AbstractModule class

public class AppModule extends AbstractModule {

    private static final Injector injector = Guice.createInjector(new AppModule());

    private final Vertx vertx = Vertx.vertx(new VertxOptions().setMetricsOptions(
            new DropwizardMetricsOptions().setEnabled(true)
    ));

    private final com.test.reactivex.db.service.DBService dbService;

    public AppModule() {

        this.dbService = DBService.createProxy(this.vertx, DB_SERVICE_ADDRESS);
    }

    @Override
    protected void configure() {
        bind(Vertx.class).toInstance(this.vertx);
        bind(EventBus.class).toInstance(this.vertx.eventBus());
        bind(FileSystem.class).toInstance(this.vertx.fileSystem());
        bind(SharedData.class).toInstance(this.vertx.sharedData());
        bind(com.test.reactivex.db.service.DBService.class).toInstance(this.dbService);
        bind(AppConfig.class).toProvider(AppConfigProvider.class).in(Singleton.class);
        //requestStaticInjection(AppDependenciesInjector.class);
        logger.info("Google guice module configuration done");
    }

    @Provides
    public static AppConfig appConfig() {
        return injector.getInstance(AppConfig.class);
    }

    public static Injector getInjector() {
        return injector;
    }
}

This is how I am using injector to inject dependencies, but problem is that I have to use injectors again.

public class GraphQLRouter {

    @Inject 
    private static AppConfig config;

    @Inject
    private com.test.reactivex.auth.service.DBService dbService;

    public GraphQLRouter() {
    // below code I want to avoid
        if (dbService == null) {
            dbService = AppModule.getInjector().getInstance(com.test.reactivex.auth.service.DBService.class);
        }
    }

    //below code I want to avoid
    static {
        if (config == null)
            config = AppModule.getInjector().getInstance(AppConfig.class);
    }

来源：https://stackoverflow.com/questions/61853490/how-to-avoid-google-guice-injector-getinstance-repetative-calls-due-to-null