模拟进行外部API调用的Typescript类

class ExternalAPIService {
  private apiUrl: string;

  constructor(apiUrl: string) {
    this.apiUrl = apiUrl;
  }

  public async fetchData(): Promise<any> {
    try {
      const response = await fetch(this.apiUrl);
      const data = await response.json();
      return data;
    } catch (error) {
      console.error('Error fetching data from external API:', error);
      throw error;
    }
  }

  public async postData(payload: any): Promise<any> {
    try {
      const response = await fetch(this.apiUrl, {
        method: 'POST',
        headers: {
          'Content-Type': 'application/json',
        },
        body: JSON.stringify(payload),
      });
      const data = await response.json();
      return data;
    } catch (error) {
      console.error('Error posting data to external API:', error);
      throw error;
    }
  }
}

const apiService = new ExternalAPIService('https://api.example.com');

// 调用fetchData方法获取数据
apiService.fetchData()
  .then((data) => {
    console.log('Data from external API:', data);
  })
  .catch((error) => {
    console.error('Error:', error);
  });

// 调用postData方法发送数据
const payload = { name: 'John Doe', email: 'johndoe@example.com' };
apiService.postData(payload)
  .then((response) => {
    console.log('Response from external API:', response);
  })
  .catch((error) => {
    console.error('Error:', error);
  });