知識點來自于下方鏈接，本文只是記錄下編碼時遇到的一些問題

(2條消息) Flutter基礎(chǔ)（十一）網(wǎng)絡(luò)請求（Dio）與JSON數(shù)據(jù)解析_BATcoder - 劉望舒-CSDN博客

總結(jié)：

1. 網(wǎng)絡(luò)請求使用dio，引用時需要在pubspec.yaml中dependencies節(jié)點下配置dio: ^4.0.0。

2. json解析使用自帶jsonDecode，json模板代碼使用 quicktype 生成，這個網(wǎng)站非常好用。

3. 在使用測試json地址（https://jsonplaceholder.typicode.com/posts）進(jìn)行測試的時候，發(fā)現(xiàn)如果什么都不設(shè)置，請求后返回的response直接toString進(jìn)行解析會出錯，原因是dio默認(rèn)的responseType為json，返回的response會吃掉引號導(dǎo)致解析報錯，手動設(shè)置responseType為plain即可正常解析。

具體的代碼如下：

import 'dart:convert';

import 'package:dio/dio.dart';
import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';

class RequestTest extends StatefulWidget {
  @override
  State<StatefulWidget> createState() {
    return new MyState();
  }
}

class MyState extends State {
  @override
  void initState() {
    super.initState();
    // loadData();
  }

  @override
  Widget build(BuildContext context) {
    return new Scaffold(
      body: new Center(
          child: new ElevatedButton(
              onPressed: loadData,
              style: new ButtonStyle(),
              child: new Text("start request!"))),
    );
  }

  loadData() async {
    String dataURL = "https://jsonplaceholder.typicode.com/posts";
    try {
      Response response =
          await Dio(BaseOptions(responseType: ResponseType.plain)).get(dataURL);
      print(
          "request complete ! code = ${response.statusCode}  message = ${response.statusMessage}");
      if (response.statusCode == 200) {
        List<User> users = userFromJson(response.data.toString());
        var firstUser = users[66];
        print(
            "parse success ---- userId = ${firstUser.userId} ,title = ${firstUser.title}");
      }
    } catch (e) {
      print('error happened  ${e.toString()}');
    }
  }
}

List<User> userFromJson(String str) =>
    List<User>.from(json.decode(str).map((x) => User.fromJson(x)));

String userToJson(List<User> data) =>
    json.encode(List<dynamic>.from(data.map((x) => x.toJson())));

class User {
  User({
    this.userId,
    this.id,
    this.title,
    this.body,
  });

  int userId;
  int id;
  String title;
  String body;

  factory User.fromJson(Map<String, dynamic> json) => User(
        userId: json["userId"],
        id: json["id"],
        title: json["title"],
        body: json["body"],
      );

  Map<String, dynamic> toJson() => {
        "userId": userId,
        "id": id,
        "title": title,
        "body": body,
      };
}