在处理SpringBoot和Angular 连接时，我通过JSON通过getmapping传递getbooks之类的数据，它将在Spring的服务器上打印，但在使用服务将这些值传递给Angular 后，Angular 不会在服务器上打印数据。

SpringBoot控制器文件-

@RestController
    public class BookController {
        
    @Autowired
    BookService bookservice;
        
            @GetMapping("/")
            public String homePage() {
                return "This is home Page";
            }
        
            @GetMapping("/addBook")
            public String addBook(int id, String name, String author) {
                bookservice.addBook(Book.builder().id(id).name(name).author(author).build());
                return "Book Added";
        
            }
        
            @GetMapping("/deleteBook")
            public String deleteBook(int id) {
                bookservice.deleteBook(id);
                return "Book deleted";
            }
        
            @GetMapping("/getBooks")
            public String getAll() {
        
                Gson gson = new Gson();
                String json = gson.toJson(bookservice.getAll());
                return json;
            }
        
        }
    
    
    #SpringBoot service file -
    



 @Service
        public class BookService {
            
            @Autowired
            BookRepo repo;
        
            public void addBook(Book book) {
                repo.save(book);
                repo.flush();
            }
            public List<Book> getAll(){
                return repo.findAll();
            }
            public void deleteBook(int id) {
                
                repo.delete(Book.builder().id(id).build());
            }
            
            
        }
    
    #Angular service.ts-
    



import { Injectable } from '@angular/core';
    import { HttpClient } from '@angular/common/http';
    
    @Injectable({
      providedIn: 'root'
    })
    export class BookService {
    
      constructor(private http : HttpClient) { }
    
    getAll(){
      return this.http.get<any>("http://localhost:8080/getBooks");
    }
    addBook(user:any){
      return this.http.get("http://localhost:8080/addBook?id="+ user.id + "&name=" +user.name + "&author="+user.author);
    }
    deleteBook(id:any){
      return this.http.get("http://localhost:8080/deleteBook?id="+id);
    }
    }
    
    #appComponent.ts -

书籍：任何;

constructor(private service:BookService) {}

  ngOnInit():void{
    this.loadData();
  }

  loadData():void {
    this.service.getAll().subscribe(response => {
      this.books = response;
      console.log(this.books);
    })
  }

#appComponent.html -


<p *ngFor="let temp in books">
    {{temp.name}} -- {{temp.author}}
</p>