在angular6中为api调用配置代理时，尝试代理请求问题时发生错误

Question

我不熟悉Angle 6，并尝试通过以下链接的代理进行API调用。

angular 6 proxy configuration for api call

但是我无法从服务器获得响应，并且终端显示以下错误

[HPM] Error occurred while trying to proxy request /api/file2.php from localhost:4200 to http://localhost:1234 (ECONNREFUSED (https://nodejs.org/api/errors.html#errors_common_system_errors)

service.ts

import { Injectable } from '@angular/core';
import { HttpClient,HttpHeaders } from '@angular/common/http';

interface myData{
    obj:Object;
}
@Injectable({
  providedIn: 'root'
})
export class RecordsService {

  constructor(private http:HttpClient) { 
    this.recordFunc();
  }
  recordFunc() {

    let headers=new HttpHeaders();
    return this.http.get<myData>('/api/file2.php');
  }
}

proxyconfig.json

 {
    "/api":{
            "target":"http://localhost:1234",
            "secure":false,
            "changeOrigin":true
        }
}

我不明白这里是什么问题。我按照视频中的说明进行操作。