Flutter JSON字符串和Map类型的转换

Map转换成Json

import 'dart:convert'
  Map userInfo={
  "username":"张三",
  "age":20
};
print(json.encode(userInfo));

Json转换成Map

String str='{"username":"张三","age":20}';
print(json.decode(str));
Map info=json.decode(str);
print(info["username"]);

Flutter Dio请求数据

dio是一个强大的Dart Http请求库，支持Restful API、FormData、拦截器、请求取消、Cookie管理、文件上传/下载、超时、自定义适配器等...

官网：

https://pub.dev/packages/dio

中文文档：

https://github.com/flutterchina/dio/blob/master/README-ZH.md

Dio的配置

dependencies:
    dio: ^4.0.6

import 'package:dio/dio.dart';

var response = await Dio().get('https://jdmall.itying.com/api/httpGet');
  print(response.data);
  print(response.data is Map);
}

Dio Get

_getData() async {
  var response = await
    Dio().get('https://jdmall.itying.com/api/httpGet',queryParameters:{
    "username":"zhangsan"
  });
  print(response.data is Map);
  print(response.data["msg"]);
}

Dio Post

_postData() async{
  var response = await
    Dio().post('https://jdmall.itying.com/api/httpPost',data: {"username":"张三
111","age":"20"});
  print(response.data);
  print(response.data is Map);
}

Dio Put

_putData() async {
  var response = await Dio().put('https://jdmall.itying.com/api/httpPut',
                                 data: {"username": "张三111", "age": "20"});
  print(response.data);
  print(response.data is Map);
}

Dio Delete

_deleteData() async {
  var response = await Dio().delete(
    'https://jdmall.itying.com/api/httpDelete',
    queryParameters: {"id": "1"});
  print(response.data);
  print(response.data is Map);
}

Dio 请求数据渲染数据示例，通过数组长度判断数据渲染数据

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

class HomePage extends StatefulWidget {
  const HomePage({super.key});

  @override
  State<HomePage> createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> {
  List _list = [];

  _getData() async {
    var response = await Dio().get('https://jdmall.itying.com/api/pcate');
    // print(response);
    setState(() {
      _list = response.data['result'];
    });
  }

  @override
  void initState() {
    super.initState();
    _getData();
  }

  @override
  Widget build(BuildContext context) {
    return _list.isNotEmpty ? ListView(
      children: _list.map((e) {
        return Column(
          children: [
            ListTile(
              title: Text(e['title']),
            ),
            const Divider(),
          ],
        );
      }).toList()
    ) : const Center(
      child: CircularProgressIndicator(),
    );
  }
}

Dio 请求数据渲染数据示例，FutureBuilder渲染数据

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

class HomePage extends StatefulWidget {
  const HomePage({super.key});

  @override
  State<HomePage> createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> {
  _getData() async {
    var response = await Dio().get('https://jdmall.itying.com/api/pcate');
    // print(response);
    return response.data["result"];
  }

  @override
  Widget build(BuildContext context) {
    return FutureBuilder(
        future: _getData(),
        builder: (context, snapshot) {
          if (snapshot.connectionState == ConnectionState.done) {
            if (snapshot.hasError) {
              return Center(child: Text("Error:${snapshot.error}"));
            } else {
              var response = snapshot.data as List;
              return ListView(
                children: response.map((value) {
                  return ListTile(
                    title: Text("${value["title"]}"),
                  );
                }).toList(),
              );
            }
          } else {
            return const Center(child: CircularProgressIndicator());
          }
        });
    ;
  }
}