Angular客户端未调用后端服务

I am developing Sample application where I am using Angular 5 for front end and Go Lang for rest services(web services). Here my angular is not calling service, but those services are working fine when I run from google by pasting url and I have added CORS in Go. Here is my angular code:

export class TestServiceService {

private url2 ='http://localhost:8000/api/books/';

  constructor(private http : HttpClient) { }

  getValues() 
  {
    debugger;
     return this.http.get(this.url2);
  };

}

Here is my Go code package main

import (
    "encoding/json"
    "fmt"
    "log"
    "net/http"

    "github.com/gorilla/mux"
)

//Book struct
type Book struct {
    RollNo    string `json:"rollNo"`
    FirstName string `json:"firstName"`
    Author    string `json:"author"`
}

var books []Book

func getBooks(w http.ResponseWriter, r *http.Request) {
    fmt.Println("Method hit")
    w.Header().Set("Content-Type", "application/json")
    json.NewEncoder(w).Encode(books)
}

func main() {
    r := mux.NewRouter()

    fmt.Println("started service")

    books = append(books, Book{RollNo: "1", FirstName: "Ravi", Author: "Dan"})

    r.HandleFunc("/api/books/", getBooks).Methods("GET")

    log.Fatal(http.ListenAndServe(":8000", r))
}

Here is the screenshot proof where the service is working fine:

Here the service method is not called with angular and there is no errors

you should import and inject the HttpClient,

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

@Injectable()
export class TestServiceService {

private url2 ='http://localhost:8000/api/books/';

constructor(private http : HttpClient) { }

getValues() 
{
    debugger;
    return this.http.get(this.url2);
};


}

How did you call services' method in angular component?

Refer to angular guide HttpClient section. https://angular.io/guide/http#getting-json-data

Because you didn't show the code for Angular component, I don't know a root cause of your ploblem. I presume you may subscribe a Observable, which is return value of getValues method. It should be like below(refer to the docs):

showConfig() {
  this.configService.getConfig()
    .subscribe((data: Config) => this.config = {
        heroesUrl: data['heroesUrl'],
        textfile:  data['textfile']
    });
}