详解flutter之网络请求dio，请求，拦截器简单示例

 import 'package:dio/dio.dart'; import 'dart:async'; import 'dart:io'; import './apidomain.dart'; import './httpHeaders.dart'; import 'package:shared_preferences/shared_preferences.dart'; class DioUtil{ static Dio dio = new Dio(); //请求部分 static Future request(url,{formData})async{ try{ Response response; dio.options.headers = httpHeaders; dio.options.contentType = ContentType.parse("application/json;charset=UTF-8"); if(formData == null){ response = await dio.post(serviceUrl+url); }else{ response = await dio.post(serviceUrl+url,data:formData); } if(response.statusCode == 200){ return response; }else{ throw Exception("接口异常R"); } }catch(e){ print("网络出现错误${e}"); } } //拦截器部分 static tokenInter(){ dio.interceptors.add(InterceptorsWrapper( onRequest:(RequestOptions options){ // 在发送请求之前做一些预处理 //我这边是在发送前到SharedPreferences（本地存储）中取出token的值，然后添加到请求头中 //dio.lock()是先锁定请求不发送出去，当整个取值添加到请求头后再dio.unlock()解锁发送出去 dio.lock(); Future future = Future(()async{ SharedPreferences prefs =await SharedPreferences.getInstance(); return prefs.getString("loginToken"); }); return future.then((value) { options.headers["Authorization"] = value; return options; }).whenComplete(() => dio.unlock()); // unlock the dio }, onResponse:(Response response) { // 在返回响应数据之前做一些预处理 return response; // continue }, onError: (DioError e) { // 当请求失败时做一些预处理 return e;//continue } )); } } 

 const httpHeaders={ 'Accept': 'application/json, text/plain, */*', 'Authorization': '666', 'Content-Type': 'application/json;charset=UTF-8', 'Origin': 'http://localhost:8080', 'Referer': 'http://localhost:8080/', 'User-Agent': 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/73.0.3683.103 Safari/537.36', }; 

 const serviceUrl = 'http://39.xxx.xxx.xx:8080';