Flutter 之网络请求Dio, FormData, 表单网络请求, x-www-form-urlencoded

Posted 2023-04-19

参考技术A 网络请求, 先想到的是dart官方维护的 http 库. 由于我们项目组网络请求都采用的表单结构, http 貌似不支持表单格式的网络请求; 后来查看 dio 库, 发现支持 FormData , 完美解决!

官方表单网络请求示例:

比葫芦画瓢, 尝试下

Flutter--网络请求dio封装网络请求框架

dio简介

• dio库支持文件的上传和下载，Cookie管理、FormData、请求/取消、拦截器等，和Android中的OkHttp库相似

基本用法

import package:dio/dio.dart;

_loadDataGet() async 
  try 
    Response response = await Dio().get("https://www.baidu.com");
    print(response);
   catch (e) 
    print(e);
  


_loadDataPost() async 
  try 
    Response response = await Dio().post("path", data: );
    print(response);
   catch (e) 
    print(e);
  

Dio单例

var dio = new Dio(BaseOptions(
  baseUrl: "url",
  connectTimeout: 5000,
  receiveTimeout: 10000,
  
  headers:
    HttpHeaders.userAgentHeader: "dio",
    "api": "1.0.0",
  ,
  contentType: ContentType.json,
  responseType: ResponseType.plain
));

Dio拦截器

• 官方示例

dio.interceptors.add(InterceptorsWrapper(
onRequest:(RequestOptions options) async 
    // 请求发送前处理
return options; //continue
,
onResponse:(Response response) async 
// 在返回响应数据之前做一些预处理
return response; // continue
,
onError: (DioError e) async 
// 当请求失败时做一些预处理
return e;//continue

));

• 注意：

• 在拦截器做request处理时，可以直接返回options,这个时候会继续处理then方法里的逻辑，如果想要完成请求并返回一些自定义的数据，可以返回一个Response对象或返回dio.resolve(data),可以使得请求终止，上层的then会被调用，then中返回的数据是自定义的数据

封装dio网络请求

• 首先创建一个单例

class HttpRequest 
  static String _baseUrl = Api.BASE_URL;
  static HttpRequest instance;

  Dio dio;
  BaseOptions options; // 基类请求配置，还可以使用Options单次请求配置，RequestOptions实际请求配置对多个域名发起请求

  CancelToken cancelToken = CancelToken();

  static HttpRequest getInstance() 
    if (instance == null) 
      instance = HttpRequest();
    
    return instance;
  

• 配置并初始化dio参数

HttpRequest() 
  options = BaseOptions(
    // 访问url
    baseUrl: _baseUrl,
    // 连接超时时间
    connectTimeout: 5000,
    // 响应流收到数据的间隔
    receiveTimeout: 15000,
    // http请求头
    headers: "version": "1.0.0",
    // 接收响应数据的格式
    responseType: ResponseType.plain,
  );
  dio = Dio(options);
  
  // 在拦截其中加入Cookie管理器
  dio.interceptors.add(CookieManager(CookieJar()));
  
  //添加拦截器
  dio.interceptors.add(InterceptorsWrapper(onRequest: (RequestOptions options) 
    // Do something before request is sent
    return options; //continue
  , onResponse: (Response response) 
    // Do something with response data
    return response; // continue
  , onError: (DioError e) 
    // Do something with response error
    return e; //continue
  ));

• 取消请求

// cancelToken可用于多个请求，也可同时取消多个请求
void cancelRequests(CancelToken token)   
    token.cancel("cancelled");

• get请求

get(url,
    data,
      options,
      cancelToken,
      BuildContext context,
      Function successCallBack,
      Function errorCallBack) async 
  Response response;
  try 
    response = await dio.get(url,
        queryParameters: data, options: options, cancelToken: cancelToken);
   on DioError catch (e) 
    handlerError(e);
  
  if (response.data != null) 
    BaseResponse baseResponse =
    BaseResponse.fromJson(json.decode(response.data));
    if (baseResponse != null) 
      switch (baseResponse.errorCode) 
        case 成功状态码:
          successCallBack(jsonEncode(baseResponse.data));
          break;
        case 其他状态码:
          errorCallBack(baseResponse.errorCode, baseResponse.errorMessage);

          break;
        default:
          errorCallBack(baseResponse.errorCode, baseResponse.errorMessage);
          break;
      
     else 
      errorCallBack(Constants.NETWORK_JSON_EXCEPTION, "网络数据问题");
    
   else 
    errorCallBack(Constants.NETWORK_ERROR, "网络出错啦，请稍后重试");
  

• 注意：

• url：请求地址
• data：请求参数
• options：请求配置
• cancelToken：取消标识

• post请求

post(url,
    data,
      options,
      cancelToken,
      BuildContext context,
      Function successCallBack,
      Function errorCallBack) async 
  Response response;
  try 
    response = await dio.post(url,
        queryParameters: data, options: options, cancelToken: cancelToken);
   on DioError catch (e) 
    handlerError(e);
  
  if (response.data != null) 
    BaseResponse baseResponse =
    BaseResponse.fromJson(json.decode(response.data));
    if (baseResponse != null) 
      switch (baseResponse.errorCode) 
        case 成功状态码:
          successCallBack(jsonEncode(baseResponse.data));
          break;
        case 其他状态码:
          errorCallBack(baseResponse.errorCode, baseResponse.errorMessage);
          break;
        default:
          errorCallBack(baseResponse.errorCode, baseResponse.errorMessage);
          break;
      
     else 
      errorCallBack(Constants.NETWORK_JSON_EXCEPTION, "网络数据问题");
    
   else 
    errorCallBack(Constants.NETWORK_ERROR, "网络出错啦，请稍后重试");
  

• 下载文件

downloadFile(urlPath, savePath) async 
  Response response;
  try 
    response = await dio.download(urlPath, savePath,onReceiveProgress: (int count, int total)
      //进度
      print("$count $total");
    );
    print(downloadFile success---------$response.data);
   on DioError catch (e) 
    print(downloadFile error---------$e);
    handlerError(e);
  
  return response.data;

• 错误处理

handlerError(DioError e) 
  if (e.type == DioErrorType.CONNECT_TIMEOUT) 
    print("连接超时");
   else if (e.type == DioErrorType.SEND_TIMEOUT) 
    print("请求超时");
   else if (e.type == DioErrorType.RECEIVE_TIMEOUT) 
    print("响应超时");
   else if (e.type == DioErrorType.RESPONSE) 
    print("响应异常");
   else if (e.type == DioErrorType.CANCEL) 
    print("请求取消");
   else 
    print("未知错误");