HttpClientModulelink
An NgModule that provides the HttpClient and associated services.
一个 NgModule，可以提供 HttpClient 及其相关服务。
说明
Interceptors can be added to the chain behind HttpClient by binding them to the multiprovider for HTTP_INTERCEPTORS.
通过把拦截器提供为 HTTP_INTERCEPTORS（允许有多个），可以把它们添加到 HttpClient 调用链的后面。
