全局变量替代，而且还得考虑参数复合问题。 @Injectable() export class DefaultRequestOptions extends BaseRequestOptions { constructor() { super(); this.headers.set('Content-Type','application/json'); } } export const requestOptionProvider = {provide: RequestOptions,useClass: DefaultRequestOptions}; //方案2:能用，比较正规的实现，但以后请求就只能用myHttp对象了，而且还要考虑参数复合问题。 export class myHttp extends Http { defaultHeaders = new Headers({ 'Content-Type': 'application/json' });

constructor(_backend: ConnectionBackend,_defaultOptions: RequestOptions,private appInitService: AppInitService) {
super(_backend,_defaultOptions);
}

get(url: string,options?: RequestOptionsArgs): Observable {
let optionBuf = new RequestOptions({
headers: this.defaultHeaders,params: {'token': this.appInitService.token}
});
//here extend options;
return super.get(url,optionBuf);
}
}

export function myHttpFactory(xhrBackend: XHRBackend,requestOptions: RequestOptions,appInitService: AppInitService): myHttp {
return new myHttp(xhrBackend,requestOptions,appInitService); // 创建myHttp对象
}

export const myHttpProvider = {
provide: myHttp,useFactory: myHttpFactory,deps: [XHRBackend,RequestOptions,AppInitService]
};