从Angular 2中的config.json获取数据

我想从配置文件加载所有url。我已经创建了名为'config.json'，ConfigurationService.ts的json文件来按键获取URL。但是我无法按键获取URL

config.json：

{
"loginUrl": "http:example/login",
"verifyUrl": "http:example/verify"
}

ConfigurationService.ts：

import {Injectable} from '@angular/core';
import {Http, Response} from '@angular/http';
import {Headers, RequestOptions} from '@angular/http';
import {Observable} from 'rxjs/Observable';

@Injectable()
export class ConfigurationService {
constructor(private http:Http) {}

private result: Object;

getConfiguration(key) {
    return this.http.get('./app/config/config.json').map(res => {
        res.json();
        this.result = res._body;
        return this.result[key]; //returns 'undefined', but when I return only 'this.result'  it shows me all json data {...}
    });
}
}

private x =this.configurationService.getConfiguration("verifyUrl").subscribe((result) => console.log(result));

auth_service.ts的一部分：

import {Injectable} from '@angular/core';
import {Http, Response} from '@angular/http';
import {Headers, RequestOptions} from '@angular/http';
import {Observable} from 'rxjs/Observable';

@Injectable()
export class ConfigurationService {
constructor(private http:Http) {}

private result: Object;

getConfiguration(key) {
    return this.http.get('./app/config/config.json').map(res => {
        res.json();
        this.result = res._body;
        return this.result[key]; //returns 'undefined', but when I return only 'this.result'  it shows me all json data {...}
    });
}
}

private x =this.configurationService.getConfiguration("verifyUrl").subscribe((result) => console.log(result));

---

例如，我如何只接收loginUrl？

我想您需要的是：

getConfiguration（键）{
返回这个.http.get（'./app/config/config.json'）.map（res=>{
this.result=res.json（）；
返回此。结果[键]；
});
}