无法将参数传递到Angular服务，Node.JS后端服务器

import { Injectable } from '@angular/core';

@Injectable()
export class MyService {
  constructor() { }

  processParameter(param: any): void {
    // 处理传递的参数
    console.log('Received parameter:', param);
    // 其他处理逻辑...
  }
}

import { Component } from '@angular/core';
import { MyService } from './my.service';

@Component({
  selector: 'app-my-component',
  template: `
    <button (click)="passParameter()">传递参数</button>
  `,
})
export class MyComponent {
  constructor(private myService: MyService) { }

  passParameter(): void {
    const param = 'Hello, World!';
    this.myService.processParameter(param);
  }
}

import { NgModule } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { MyService } from './my.service';
import { MyComponent } from './my.component';

@NgModule({
  imports: [BrowserModule],
  declarations: [MyComponent],
  providers: [MyService], // 添加服务提供商
  bootstrap: [MyComponent]
})
export class AppModule { }

const express = require('express');
const app = express();

app.post('/api/process', (req, res) => {
  const param = req.body.param;
  // 处理传递的参数
  console.log('Received parameter:', param);
  // 其他处理逻辑...
  res.send('Parameter processed successfully');
});

app.listen(3000, () => {
  console.log('Server is running on port 3000');
});

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

@Injectable()
export class MyService {
  constructor(private http: HttpClient) { }

  processParameter(param: any): void {
    const url = 'http://localhost:3000/api/process';
    const body = { param: param };
    this.http.post(url, body).subscribe(response => {
      console.log('Server response:', response);
      // 其他处理逻辑...
    });
  }
}

import { NgModule } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { HttpClientModule } from '@angular/common/http';
import { MyService } from './my.service';
import { MyComponent } from './my.component';

@NgModule({
  imports: [BrowserModule, HttpClientModule], // 导入HttpClientModule
  declarations: [MyComponent],
  providers: [MyService],
  bootstrap: [MyComponent]
})
export class AppModule { }