Angular2中如何使用ngx-translate进行国际化

ng new my-project 

npm install --save @ngx-translate/core 
npm install --save @ngx-translate/http-loader 

import { TranslateModule, TranslateLoader } from '@ngx-translate/core';
import { TranslateHttpLoader } from '@ngx-translate/http-loader';

export function HttpLoaderFactory(http:Http){
 return new TranslateHttpLoader(http, './assets/i18n/', '.json');
}
@NgModule({
 declarations: [
  AppComponent
 ],
 imports: [
  ...
  TranslateModule.forRoot({
   loader:{
    provide:TranslateLoader,
    useFactory:HttpLoaderFactory,
    deps:[Http]
   }
  }

  )
 ],
 providers: [],
 bootstrap: [AppComponent]
})

//zh-CN.json
{
  "welcome":"欢迎使用本应用",
  "hello":"你好",
  "get-lang":"获取语言类型"
}

//en.json
{
  "welcome":"welcome to this app",
  "hello":"Hola"
}

import { TranslateService } from '@ngx-translate/core'
@Component({
 ...
})
export class AppComponent {
 constructor(private translate: TranslateService) {
  //添加语言支持
  translate.addLangs(['zh-CN', 'en']);
  //设置默认语言，一般在无法匹配的时候使用
  translate.setDefaultLang('zh-CN');

  //获取当前浏览器环境的语言比如en、 zh
  let broswerLang = translate.getBrowserLang();
  translate.use(broswerLang.match(/en|zh-CN/) ? broswerLang : 'zh-CN');
 }

 changeLang(lang) {
  console.log(lang);
  this.translate.use(lang);
 }
 toggleLang() {
  console.log(this.translate.getBrowserLang());
  //获取语言风格，相当于更详细的语言类型，比如zh-CN、zh-TW、en-US
  console.log(this.translate.getBrowserCultureLang());
 }
}

<div>
 <h2>{{ title | translate }}</h2>
 <label>
  {{ 'hello' | translate }}
  <select #langSelect (change)="changeLang(langSelect.value)">
   <option *ngFor="let lang of translate.getLangs()" [value]="lang" [selected]="lang === translate.currentLang">{{ lang }}</option>
  </select>
 </label>
</div>
<button (click)="toggleLang()">{{'get-lang' | translate}}</button>