一、第一种简单封装

// Constants.ets
export const BASE_URL: string = 'https://lblbc.cn/';

// HttpUtil.ets
import { BASE_URL } from './Constants';
import http from '@ohos.net.http';

export function httpRequestGet(url: string) {
  url = BASE_URL + url
  let httpRequest = http.createHttp();
  var header = {
    'Content-Type': 'application/json',
  }
  let responseResult = httpRequest.request(url, {
    method: http.RequestMethod.GET,
    header: header
  });
  let serverData: {
    code,
    data: any,
    msg: string | Resource
  } = { code: 0, data: '', msg: '' };
  // 处理数据，并返回
  return responseResult.then((value) => {
    if (value.responseCode === 200) {
      // 获取返回数据
      let result = `${value.result}`;
      let resultJson = JSON.parse(result);
      serverData.data = resultJson.data;
      serverData.code = resultJson.code;
      serverData.msg = resultJson.msg;
    } else {
      serverData.code = value.responseCode;
    }
    return serverData;
  }).catch(() => {
    serverData.msg = '调用接口失败';
    return serverData;
  })
}

export function httpRequestDel(url: string) {
  url = BASE_URL + url
  let httpRequest = http.createHttp();
  var header = {
    'Content-Type': 'application/json',
  }
  let responseResult = httpRequest.request(url, {
    method: http.RequestMethod.DELETE,
    header: header
  });
  let serverData: {
    code,
    data: any,
    msg: string | Resource
  } = { code: 0, data: '', msg: '' };
  // 处理数据，并返回
  return responseResult.then((value) => {
    if (value.responseCode === 200) {
      // 获取返回数据
      let result = `${value.result}`;
      let resultJson = JSON.parse(result);
      serverData.data = resultJson.data;
      serverData.code = resultJson.code;
      serverData.msg = resultJson.msg;
    } else {
      serverData.code = value.responseCode;
    }
    return serverData;
  }).catch(() => {
    serverData.msg = '调用接口失败';
    return serverData;
  })
}

export function httpRequestPost(url: string, params: any) {
  url = BASE_URL + url
  let httpRequest = http.createHttp();
  var user = User.get()
  var header = {
    'Content-Type': 'application/json',
  }
  let responseResult = httpRequest.request(url, {
    method: http.RequestMethod.POST,
    extraData: params,
    header: header
  });
  let serverData: {
    code,
    data: any,
    msg: string | Resource
  } = { code: 0, data: '', msg: '' };
  // 处理数据，并返回
  return responseResult.then((value) => {
    if (value.responseCode === 200) {
      // 获取返回数据
      let result = `${value.result}`;
      let resultJson = JSON.parse(result);
      serverData.data = resultJson.data;
      serverData.code = resultJson.code;
      serverData.msg = resultJson.msg;
    } else {
      serverData.code = value.responseCode;
    }
    return serverData;
  }).catch((e) => {
    console.log(e)
    serverData.msg = '调用接口失败';
    return serverData;
  })
}

export function httpRequestPut(url: string, params: any) {
  url = BASE_URL + url
  let httpRequest = http.createHttp();
  var user = User.get()
  var header = {
    'Content-Type': 'application/json',
  }
  let responseResult = httpRequest.request(url, {
    method: http.RequestMethod.PUT,
    extraData: params,
    header: header
  });
  let serverData: {
    code,
    data: any,
    msg: string | Resource
  } = { code: 0, data: '', msg: '' };
  // 处理数据，并返回
  return responseResult.then((value) => {
    if (value.responseCode === 200) {
      // 获取返回数据
      let result = `${value.result}`;
      let resultJson = JSON.parse(result);
      serverData.data = resultJson.data;
      serverData.code = resultJson.code;
      serverData.msg = resultJson.msg;
    } else {
      serverData.code = value.responseCode;
    }
    return serverData;
  }).catch((e) => {
    console.log(e)
    serverData.msg = '调用接口失败';
    return serverData;
  })
}

二、第二种使用泛型封装

// 1、创建RequestOption.ets 配置类
/**
 * <pre>
 * @desc  : 网络请求配置
 * </pre>
 */
export interface RequestOptions {

  /**
   * Request url.
   */
  url?: string;

  /**
   * Request method.
   */
  method?: RequestMethod; // default is GET

  /**
   * Request url queryParams  .
   */
  queryParams ?: Record<string, string>;

  /**
   * Additional data of the request.
   * extraData can be a string or an Object (API 6) or an ArrayBuffer(API 8).
   */
  extraData?: string | Object | ArrayBuffer;

  /**
   * HTTP request header.
   */
  header?: Object; // default is 'content-type': 'application/json'

}

export enum RequestMethod {
  OPTIONS = "OPTIONS",
  GET = "GET",
  HEAD = "HEAD",
  POST = "POST",
  PUT = "PUT",
  DELETE = "DELETE",
  TRACE = "TRACE",
  CONNECT = "CONNECT"
}

//  2、创建HttpCore.ets核心类
import http from '@ohos.net.http';
import { RequestOptions } from './RequestOptions';

/**
 * Http请求器
 */
export class HttpCore {

  /**
   * 发送请求
   * @param requestOption
   * @returns Promise
   */
  request<T>(requestOption: RequestOptions): Promise<T> {
    return new Promise<T>((resolve, reject) => {
      this.sendRequest(requestOption)
        .then((response) => {
          if (typeof response.result !== 'string') {
            reject(new Error('Invalid data type'));

          } else {
            let bean: T = JSON.parse(response.result);
            if (bean) {
              resolve(bean);
            } else {
              reject(new Error('Invalid data type,JSON to T failed'));
            }

          }
        })
        .catch((error) => {
          reject(error);
        });
    });
  }


  private sendRequest(requestOption: RequestOptions): Promise<http.HttpResponse> {

    // 每一个httpRequest对应一个HTTP请求任务，不可复用
    let httpRequest = http.createHttp();

    let resolveFunction, rejectFunction;
    const resultPromise = new Promise<http.HttpResponse>((resolve, reject) => {
      resolveFunction = resolve;
      rejectFunction = reject;
    });

    if (!this.isValidUrl(requestOption.url)) {
      return Promise.reject(new Error('url格式不合法.'));
    }

    let promise = httpRequest.request(this.appendQueryParams(requestOption.url, requestOption.queryParams), {
      method: requestOption.method,
      header: requestOption.header,
      extraData: requestOption.extraData, // 当使用POST请求时此字段用于传递内容
      expectDataType: http.HttpDataType.STRING // 可选，指定返回数据的类型
    });

    promise.then((response) => {

      console.info('Result:' + response.result);
      console.info('code:' + response.responseCode);
      console.info('header:' + JSON.stringify(response.header));


      if (http.ResponseCode.OK !== response.responseCode) {
        throw new Error('http responseCode !=200');
      }
      resolveFunction(response);

    }).catch((err) => {
      rejectFunction(err);
    }).finally(() => {
      // 当该请求使用完毕时，调用destroy方法主动销毁。
      httpRequest.destroy();
    })
    return resultPromise;
  }


  private appendQueryParams(url: string, queryParams: Record<string, string>): string {

    // todo 使用将参数拼接到url上
    return url;
  }

  private isValidUrl(url: string): boolean {

    //todo 实现URL格式判断
    return true;

  }
}

export const httpCore = new HttpCore();

// 3、创建HttpManager.ets核心类
import { RequestOptions } from './RequestOptions';
import { httpCore as HttpCore } from './HttpCore';
/**
 * <pre>
 * @desc       : 对外管理器
 * </pre>
 */
export class HttpManager {
  private static mInstance: HttpManager;

  // 防止实例化
  private constructor() {
  }

  static getInstance(): HttpManager {
    if (!HttpManager.mInstance) {
      HttpManager.mInstance = new HttpManager();
    }
    return HttpManager.mInstance;
  }

  request<T>(option: RequestOptions): Promise<T> {
    return HttpCore.request(option);
  }
}

// 4、index.ets对组件导出
export { HttpManager } from './HttpManager';
export { RequestMethod } from './RequestOptions';

// 5、添加网络权限，在module.json5文件中
 "requestPermissions": [
      {
        "name": 'ohos.permission.INTERNET'
      }
 ]

// 6、页面中使用示例
handleClick() {
    HttpManager.getInstance()
      .request<TestBean>({
        method: RequestMethod.GET,
        url: 'https://jsonplaceholder.typicode.com/todos/1' //公开的API
      })
      .then((result) => {
        console.info(JSON.stringify(result));
      })
      .catch((err) => {
        console.error(JSON.stringify(err));
      });
  }

// 7、TestBean.ets
/**
 * <pre>
 * @desc       : 测试Bean
 * </pre>
 */
export interface TestBean {

  /**
   * {
   "userId": 1,
   "id": 1,
   "title": "delectus aut autem",
   "completed": false
   }
   */

  userId: number,
  id: number,
  title: string,
  completed: boolean

}