flutter Dio()网络请求

一、Flutter JSON 字符串和 Map 类型的转换

  import 'dart:convert'

  var mapData={"name":"张三","age":"20"};

  var strData='{"name":"张三","age":"20"}';

  print(json.encode(mapData)); //Map 转换成 Json 字符串

  print(json.decode(strData)); //Json 字符串转化成 Map 类型

 

 

二、使用 官方http 库进行网络请求

  请参考官方文档：https://pub.dev/packages/http 

 

三、Flutter Dio 库

  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...

  https://pub.dev/packages/dio

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

 

官方http 案例代码-----------下面有dio http 代码案例

 

import 'package:flutter/material.dart';
import 'package:http/http.dart' as http;
import 'dart:convert';


class HttpPage extends StatefulWidget {
  HttpPage({Key key}) : super(key: key);

  _HttpDemoState createState() => _HttpDemoState();
}

class _HttpDemoState extends State {

  List _list=[];

  @override
  initState() {
    // TODO: implement initState
    super.initState();
    this._getData();
  }
  _getData() async{
    var apiUrl="http://a.itying.com/api/productlist";
    var result=await http.get(apiUrl);
    if(result.statusCode==200){
      print(result.body);
      setState(() {
        this._list=json.decode(result.body)["result"];
      });
    }else{
      print("失败${result.statusCode}");
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
        appBar: AppBar(
          title: Text("请求数据Demo"),
        ),
        body: this._list.length>0?ListView(
          children: this._list.map((value){
            return ListTile(
              title: Text(value["title"]),
            );
          }).toList(),
        ):Text("加载中...")
    );
  }
}

dio http 代码案例 

dio: ^3.0.9

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

class UpDown extends StatefulWidget{
  UpDown({Key key});
  _UpDown createState() => _UpDown();
}

class _UpDown extends State<UpDown> {
  @override
  var list = [];
  var page = 1;
  var pageFlag = true;
  var _scrollController = ScrollController();
  initState() {
    super.initState();
    _getData();
    _scrollController.addListener(() {     // 上拉加载
      var _scrollTop = _scrollController.position.pixels; //获取滚动条下拉的距离
      var _scrollHeight = _scrollController.position.maxScrollExtent; //获取整个页面的高度
      if(_scrollTop >= _scrollHeight - 20) {
        _getData();
      }
    });
  }
  // 获取数据
  _getData() async{
    if(pageFlag == false) return;
    var response = await Dio().get('http://www.phonegap100.com/appapi.php?a=getPortalList&catid=20&page=${page}');
    var res = json.decode(response.data)['result'];
    setState(() {
      list.addAll(res);
      page++;
    });
    if(res.length < 20) {
      setState(() {
        pageFlag = false;
      });
    }
  }

  // 下拉刷新
  Future<void> _onRefresh() async {
    await Future.delayed(
        Duration(
            milliseconds: 2000), () {
              list = [];
              page = 1;
              _getData();
      });
  }
  Widget build(BuildContext context) {
    // TODO: implement build
    return Scaffold(
      appBar: AppBar(title: Text('上拉加载-下拉刷新'),),
      body: list.length > 0 ? RefreshIndicator(
        onRefresh: _onRefresh,
        child: ListView.builder(
          controller: _scrollController,
          itemCount: list.length,
          itemBuilder: (context, index) {
            return Column(
              children: <Widget>[
                Container(
                  padding: EdgeInsets.only(top: 5, bottom: 5, left: 5),
                  alignment: Alignment.centerLeft,
                  child: Text('${list[index]['title']}', maxLines: 1, overflow: TextOverflow.ellipsis),
                ),
                Divider(),
                index == list.length - 1 ? getMoreTips(flag: this.pageFlag) : SizedBox()
              ],
            );
          },
        ),
      ) : getMoreTips(flag: this.pageFlag)
    );
  }
}

class getMoreTips extends StatelessWidget{ // 底部的转圈和文字
  var flag = true;
  getMoreTips({Key key, this.flag}) : super(key: key);
  @override
  Widget build(BuildContext context) {
    // TODO: implement build
    return Center(
      child: flag ? Row(
        mainAxisAlignment: MainAxisAlignment.center,
        children: <Widget>[
          Text('正在加载...'),
          SizedBox( 10),
          CircularProgressIndicator(strokeWidth: 2)
        ],
      ) : Column(
        mainAxisAlignment: MainAxisAlignment.center,
        children: <Widget>[
          Text('没有更多数据了'),
          SizedBox(height: 10),
        ],
      ),
    );
  }
}

Dio封装 带拦截器

import 'dart:convert';
import 'package:dio/dio.dart';

import 'utils.dart';

var dio = Dio();

interceptors () async{
//  dio.options.contentType = 'application/json;charset=UTF-8';
//  dio.options.headers = {'testHeader':'aaaa'};

  var tokens = await Storage.getString('token');
  dio.options.baseUrl = '';
  dio.options.connectTimeout = 15000;
  dio.options.receiveTimeout = 15000;
  dio.interceptors.add(
    InterceptorsWrapper(
        onRequest: (options) async {
//          print("method = ${options.method.toString()}");
//          print("url = ${options.uri.toString()}");
//          print("headers = ${options.headers}");
//          print("params = ${options.queryParameters}");
//          此处可网络请求之前做相关配置，比如会所有请求添加token
//          options.queryParameters['token'] = 'testtoken123443423';
//          options.headers["token"] = "testtoken123443423";
//          if (tokens == null) {
//            dio.lock();
//            return dio.get('/token').then((e) {
//
//              options.queryParameters['token'] = e.data['data']['token'];
//              Storage.setString('token', {token: e.data['data']['token']});
//
//              return options;
//            }).whenComplete(() => dio.unlock());
//          } else {
//            options.queryParameters['token'] = 'testtoken123443423';
//            return options;
//          }

          return options;
        },
        onResponse: (response) {
          //此处拦截工作在数据返回之后，可在此对dio请求的数据做二次封装或者转实体类等相关操作
          return response;
        },
        onError: (error) {
          //处理错误请求
          return error;
        }),
  );

}
class DioHttp {

  static const downloadUrl = 'https://dev1.mifengff.com/obhcx4';

//  DioHttp.get(
//  'http://www.phonegap100.com/appapi.php?a=getPortalList',
//  queryParameters: {
//  'catid': 20, 'page': page
//  },
//  success: (e) {
//  setState(() {list.addAll(e);page++;});
//  if(e.length < 20) {setState(() {pageFlag = false;});}
//  });

  static get (url, {queryParameters, success = '', error = '', headers = '', requests = '', statusCodes = ''}) async{
    interceptors();
    try{
      var response = await dio.get(dio.options.baseUrl + url, queryParameters: queryParameters ?? {});
      if(headers != '') {headers(response.headers);}
      if(requests != '') {requests(response.request);}
      if(statusCodes != '') {statusCodes(response.statusCode);}

      if(response.statusCode == 200) {
        var res = json.decode(response.data)['result'];
        if(success != '') {success(res);}
      } else {
        if(error != '') {error(response);}
        throw Exception('erroor: $response');
      }
    } catch (e) {
      formatError(e);
      throw Exception('erroor: $e');
    }
  }

  static post (url, {data, success = '', error = '', headers = '', requests = '', statusCodes = '', onSendProgress}) async{
    interceptors();
    try{
      var response = await dio.post(dio.options.baseUrl + url, data: data ?? {}, onSendProgress: onSendProgress ?? () {});

      if(headers != '') {headers(response.headers);}
      if(requests != '') {requests(response.request);}
      if(statusCodes != '') {statusCodes(response.statusCode);}

      if(response.statusCode == 200) {
        var res = json.decode(response.data)['result'];
        if(success != '') {success(res);}
      } else {
        if(error != '') {error(response);}
        throw Exception('erroor: $response');
      }
    } catch (e) {
      formatError(e);
      throw Exception('erroor: $e');
    }
  }

  static download (url, saveUrl, {success, error, onReceiveProgress}) async{
    interceptors();
    try{
      var response = await dio.download(dio.options.baseUrl + url, saveUrl, onReceiveProgress: onReceiveProgress ?? () {});

      if(response.statusCode == 200) {
        var res = json.decode(response.data)['result'];
        if(success != '') {success(res);}
      } else {
        if(error != '') {error(response);}
        throw Exception('erroor: $response');
      }
    } catch (e) {
      formatError(e);
      throw Exception('erroor: $e');
    }
  }

  static formData (url, data, {success, error}) async{
    interceptors();
//    var formData = FormData.fromMap({
//      'name': 'wendux',
//      'age': 25,
//    });
    try{
      var response = await dio.post(dio.options.baseUrl + url, data: data ?? {});

      if(response.statusCode == 200) {
        var res = json.decode(response.data)['result'];
        if(success != '') {success(res);}
      } else {
        if(error != '') {error(response);}
        throw Exception('erroor: $response');
      }
    } catch (e) {
      formatError(e);
      throw Exception('erroor: $e');
    }
  }
}
//  error统一处理
void formatError(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("出现异常404 503");
  } else if (e.type == DioErrorType.CANCEL) {

    print("请求取消");
  } else {

    print("未知错误");
  }
}