Angular 2 教程（英雄之旅）：例外：响应状态：404 未找到 URL：null

Question

我应用来自https://angular.io/docs/ts/latest/tutorial/toh-pt6.html 的代码并且运行良好，除了页面英雄详细信息：http://localhost:3000/detail/12

文件 app.module.ts

import './rxjs-extensions';
import { NgModule }      from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { FormsModule }   from '@angular/forms';
import { HttpModule }    from '@angular/http';
import { APP_BASE_HREF } from '@angular/common';

import { AppRoutingModule } from './app-routing.module';

// Imports for loading & configuring the in-memory web api
import { InMemoryWebApiModule } from 'angular-in-memory-web-api';
import { InMemoryDataService }  from './in-memory-data.service';

import { AppComponent }         from './app.component';
import { DashboardComponent }   from './dashboard.component';
import { HeroesComponent }      from './heroes.component';
import { HeroDetailComponent }  from './hero-detail.component';
import { HeroService }          from './hero.service';
import { HeroSearchComponent }  from './hero-search.component';

@NgModule({
  imports: [
    BrowserModule,
    FormsModule,
    HttpModule,
    InMemoryWebApiModule.forRoot(InMemoryDataService),
    AppRoutingModule
  ],
  declarations: [
    AppComponent,
    DashboardComponent,
    HeroDetailComponent,
    HeroesComponent,
    HeroSearchComponent
  ],
  providers: [ {provide: APP_BASE_HREF, useValue : '/' }, HeroService ],
  bootstrap: [ AppComponent ]
})
export class AppModule { }

文件 hero.service.ts

import { Injectable }    from '@angular/core';
import { Headers, Http } from '@angular/http';

import 'rxjs/add/operator/toPromise';

import { Hero } from './hero';

@Injectable()
export class HeroService {

  private headers = new Headers({'Content-Type': 'application/json'});
  private heroesUrl = 'app/heroes';  // URL to web api

  constructor(private http: Http) { }

  getHeroes(): Promise<Hero[]> {
    return this.http.get(this.heroesUrl)
               .toPromise()
               .then(response => response.json().data as Hero[])
               .catch(this.handleError);
  }

  getHero(id: number): Promise<Hero> {
    return this.getHeroes()
               .then(heroes => heroes.find(hero => hero.id === id));
  }

  delete(id: number): Promise<void> {
    const url = `${this.heroesUrl}/${id}`;
    return this.http.delete(url, {headers: this.headers})
      .toPromise()
      .then(() => null)
      .catch(this.handleError);
  }

  create(name: string): Promise<Hero> {
    return this.http
      .post(this.heroesUrl, JSON.stringify({name: name}), {headers: this.headers})
      .toPromise()
      .then(res => res.json().data)
      .catch(this.handleError);
  }

  update(hero: Hero): Promise<Hero> {
    const url = `${this.heroesUrl}/${hero.id}`;
    return this.http
      .put(url, JSON.stringify(hero), {headers: this.headers})
      .toPromise()
      .then(() => hero)
      .catch(this.handleError);
  }

  private handleError(error: any): Promise<any> {
    console.error('An error occurred', error); // for demo purposes only
    return Promise.reject(error.message || error);
  }
}

文件索引.html

<!DOCTYPE html>
<html>
  <head>
    <title>Angular QuickStart</title>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1">
    <link rel="stylesheet" href="styles.css">

    <!-- Polyfill(s) for older browsers -->
    <script src="node_modules/core-js/client/shim.min.js"></script>

    <script src="node_modules/zone.js/dist/zone.js"></script>
    <script src="node_modules/reflect-metadata/Reflect.js"></script>
    <script src="node_modules/systemjs/dist/system.src.js"></script>

    <script src="systemjs.config.js"></script>
    <script>
      System.import('app').catch(function(err){ console.error(err); });
    </script>
  </head>

  <body>
    <my-app>Loading...</my-app>
  </body>
</html>

请帮助我完成 Angular 2 教程（英雄之旅）中的第一个演示。谢谢！

Answer 1

根据tutorial，你应该改变

private heroesUrl = 'app/heroes'; // URL to web api

到

private heroesUrl = 'api/heroes'; // URL to web api

Answer 2

我不确定，但是好像不完整的Url：

private heroesUrl = 'app/heroes';  // URL to web api

检查您是否获得完整的 URL。