Angular 2/4 多语言 国际化支持

　ngx-translate  包使用

1.  安装

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

2. app.module.ts

import { BrowserModule } from '@angular/platform-browser';
import { NgModule } from '@angular/core';
import { FormsModule } from '@angular/forms';
import { HttpModule, Http } from '@angular/http';
import { TranslateModule, TranslateLoader } from '@ngx-translate/core';
import { TranslateHttpLoader } from '@ngx-translate/http-loader';

import { AppComponent } from './app.component';

export function createTranslateLoader(http: Http) {
    return new TranslateHttpLoader(http, './assets/i18n/', '.json');
}

@NgModule({
  declarations: [
    AppComponent
  ],
  imports: [
    BrowserModule,
    TranslateModule.forRoot({
            loader: {
                provide: TranslateLoader,
                useFactory: (createTranslateLoader),
                deps: [Http]
            }
        }),
    FormsModule,
    HttpModule
  ],
  providers: [],
  bootstrap: [AppComponent]
})
export class AppModule { }

加载TranslateModule的loader, parser 或者missing translations handler

TranslateModule.forRoot();

默认的http loader

TranslateModule.forRoot({
            loader: {
                provide: TranslateLoader,
                useFactory: (createTranslateLoader),
                deps: [Http]
            }
        }),

实现AOT编译

export function createTranslateLoader(http: Http) {
    return new TranslateHttpLoader(http, './assets/i18n/', '.json');
}

TranslateHttpLoader 加载 "/assets/i18n/[lang].json"  文件， [lang] 为语言文件名

初始化 TranslateService 

import { Component } from '@angular/core';
import { TranslateService } from '@ngx-translate/core';


@Component({
  selector: 'app-root',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.css']
})
export class AppComponent {

  constructor(public translate: TranslateService) {
        // this language will be used as a fallback when a translation isn't found in the current language
        translate.addLangs(["en", "ch"]);
        
        let browserLang = translate.getBrowserLang();
        console.log("browser languague: " + browserLang);
        translate.use(browserLang.match(/en|ch/) ? browserLang : 'en');
    }
}

语言文件 /assets/i18n/ch.json

{
  "HOME": {
    "TITLE": "你好, Angular ngx-translate!",
    "SELECT": "更改语言"
  }
}

/assets/i18n/en.json

{
  "HOME": {
    "TITLE": "Hello Angular with ngx-translate!",
    "SELECT": "Change language"
  }
}

app.component.html 文件

<div>
  <h2>{{ 'HOME.TITLE' | translate }}</h2>
  <label>
    {{ 'HOME.SELECT' | translate }}
    <select #langSelect (change)="translate.use(langSelect.value)">
      <option *ngFor="let lang of translate.getLangs()" [value]="lang" [selected]="lang === translate.currentLang">{{ lang }}</option>
    </select>
  </label>
</div>

效果