angular prod模式不注入服务

我正在使用 angular 7 和 ngx-facebook FacebookService 服务。

应用模块ts

import {BrowserModule} from '@angular/platform-browser';
import {NgModule} from '@angular/core';

import {FacebookModule} from 'ngx-facebook';

import {AppComponent} from './app.component';
import {UsercardDirective} from './usercard.directive';
import {UsercardComponent} from './usercard/usercard.component';
import {BodyComponent} from './body/body.component';
import {BoardComponent} from './board/board.component';
import {HttpClientModule} from "@angular/common/http";
import { LandingComponent } from './landing/landing.component';

@NgModule({
  declarations: [
    AppComponent,
    UsercardDirective,
    UsercardComponent,
    BodyComponent,
    BoardComponent,
    LandingComponent
  ],
  imports: [
    BrowserModule,
    FacebookModule.forRoot(),
    HttpClientModule
  ],
  providers: [],
  bootstrap: [AppComponent]
})
export class AppModule {
}    

import {Component, OnInit} from '@angular/core';
import {FacebookService} from 'ngx-facebook';
import {IndexserviceService} from './indexservice.service';

@Component({
  selector: 'app-root',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.css'],
  providers: [IndexserviceService, FacebookService]
})
export class AppComponent implements OnInit {
  title = 'indexng';

  constructor(private inSrvc: IndexserviceService, private fb: FacebookService) {}

  ngOnInit() {
    console.log(this.fb);
    this.inSrvc.indexInit(this.fb);
  }
}

我得到一些奇怪的结果。当我测试这个的时候 ng-serve 很好用。

然后我跑了 ng g --prod 并将应用程序放入spring boot应用程序。在那里我得到的控制台输出 this.fb 作为一个空对象。

IndexserviceService 工作正常。 indexInit 正确调用