Flutter 網路請求的三種簡單實現

概述：本文主要講解了flutter網路請求三種方式 flutter自帶的HttpClient、 第三方庫http 和 第三方庫Dio 的簡單實現 GET 和 POST請求，本文是筆者學習Flutter網路模組知識總結，若有問題還望不膩賜教。

一.系統自帶HttpClient

1.使用中溫馨提示

1.1.匯入庫

import 'dart:io'; // 網路請求
import 'dart:convert'; // 資料解析
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1.2.Uri的多種初始化方式

// 方法1
Uri uri = Uri(scheme: 'https', host: 'app.xxx.com', path: homeNoviceListUrl);
// 方法2
Uri uri = Uri.https('app.xxx.com', homeNoviceListUrl);
// uri方法3
Uri uri = Uri.parse(baseUrl + homeNoviceListUrl);
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2.簡單使用

2.1.GET請求

// 1.1 HttpClient - get 

void loadData_sys_get() async {
print('------loadData_sys_get--------');

var httpClient = new HttpClient();
var params = Map<String, String>();

// uri方法1
Uri uri =
    Uri(scheme: 'https', host: 'app.xxx.com', path: homeNoviceListUrl);

// uri方法2
// Uri uri = Uri.https(
//     'app.xxx.com', homeNoviceListUrl);

// uri方法3
// Uri uri = Uri.parse(baseUrl + homeNoviceListUrl);

var request = await httpClient.getUrl(uri);

var headers = Map<String, String>();
headers['loginSource'] = 'IOS';
headers['useVersion'] = '3.1.0';
headers['isEncoded'] = '1';
headers['bundleId'] = 'com.xxx.xxx';

request.headers.add("loginSource", "IOS");
request.headers.add("useVersion", "3.1.0");
request.headers.add("isEncoded", "1");
request.headers.add("bundleId", "com.xxx.xxx");

var response = await request.close();
var responseBody = await response.transform(Utf8Decoder()).join();

if (response.statusCode == HttpStatus.ok) {
  print('請求頭：${response.headers}');

  print('111請求成功代發資料為:\n $responseBody');
  print('--------------');
  Map data = jsonDecode(responseBody);
  print('222請求成功代發資料為:\n $data');
} else {
  print('\n\n\n11111==請求失敗${response.statusCode}');
}
}
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2.2.POST請求

注意點：請求引數需要編碼後放在request中

void loadData_sys_post() async {
print('------loadData_sys_post--------');

HttpClient httpClient = new HttpClient();

// queryParameters get請求的查詢引數(適用於get請求？？？是嗎？？？)
// Uri uri = Uri(
//     scheme: "https", host: "app.xxx.com", path: homeRegularListUrl);
// HttpClientRequest request = await httpClient.postUrl(uri);

var url = baseUrl + homeRegularListUrl;
HttpClientRequest request = await httpClient.postUrl(Uri.parse(url));

// 設定請求頭
request.headers.set("loginSource", "IOS");
request.headers.set("useVersion", "3.1.0");
request.headers.set("isEncoded", "1");
request.headers.set("bundleId", "com.xxx.xxx");
// Content-Type大小寫都ok
request.headers.set('content-type', 'application/json');

/// 新增請求體
/// https://stackoverflow.com/questions/50278258/http-post-with-json-on-body-flutter-dart/50295533
Map jsonMap = {'currentPage': '1'};
request.add(utf8.encode(json.encode(jsonMap)));

HttpClientResponse response = await request.close();
String responseBody = await response.transform(utf8.decoder).join();
if (response.statusCode == HttpStatus.ok) {
  print('請求成功');
  print(response.headers);
  print(responseBody);
}
}
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二.請求第三方庫 http

1.使用中溫馨提示

1.1.新增依賴

dependencies:
  http: ^0.12.0 #latest version
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1.2.匯入庫

import 'package:http/http.dart' as http; //匯入前需要配置
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2.簡單使用

2.1. GET請求

2.2.1. http - get1

  void loadData_http_get() async {
    print('------loadData_http_get--------');

    var client = http.Client();

    var uri = Uri.parse(baseUrl + homeNoviceListUrl);

    http.Response response = await client.get(uri);

    if (response.statusCode == HttpStatus.ok) {
      print(response.body);
    } else {
      print('請求失敗 code 碼為${response.statusCode}');
    }
  }
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2.2. http - get簡便方法（鏈式程式設計）

void loadData_http_get_convenience() async {
    print('------簡便方法loadData_http_get_convenience--------');

    var uri = Uri.parse(baseUrl + homeNoviceListUrl);

    http.Client().get(uri).then((http.Response response) {
      if (response.statusCode == HttpStatus.ok) {
        print(response.body);
      } else {
        print('請求失敗 code 碼為${response.statusCode}');
      }
    });
  }
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2.2. POST請求

2.2.1. http - post

  void loadData_http_post() async {
    print('------ loadData_http_post --------');

    var headers = Map<String, String>();
    headers["loginSource"] = "IOS";
    headers["useVersion"] = "3.1.0";
    headers["isEncoded"] = "1";
    headers["bundleId"] = "com.xxx.xxx";
    headers["loginSource"] = "IOS";
    headers["Content\-Type"] = "application/json";

    Map params = {'currentPage': '1'};
    // 巢狀兩層都可以，但是具體哪個好還有待確認？？？？
    var jsonParams = utf8.encode(json.encode(params));
    // var jsonParams = json.encode(params);

    var httpClient = http.Client();

    var uri = Uri.parse(baseUrl + homeNoviceListUrl);

    http.Response response =
        await httpClient.post(uri, body: jsonParams, headers: headers);

    if (response.statusCode == HttpStatus.ok) {
      print(response.body);
    } else {
      print('請求失敗 code 碼���${response.statusCode}');
    }
  }
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2.2.2. http - Post簡便方法（鏈式程式設計）

  void loadData_http_post_convenience() async {
    print('------ loadData_http_post --------');

    var headers = Map<String, String>();
    headers["loginSource"] = "IOS";
    headers["useVersion"] = "3.1.0";
    headers["isEncoded"] = "1";
    headers["bundleId"] = "com.xxx.xxx";
    headers["loginSource"] = "IOS";
    headers["Content\-Type"] = "application/json";

    Map params = {'currentPage': '1'};
    // 巢狀兩層都可以，但是具體哪個好還有待確認？？？？
    var jsonParams = utf8.encode(json.encode(params));
    // var jsonParams = json.encode(params);

    var httpClient = http.Client();

    var url = baseUrl + homeRegularListUrl;

    httpClient.post(url, body: jsonParams, headers: headers).then((response) {
      print("Response status: ${response.statusCode}");
      print("Response body: ${response.body}");
    }).whenComplete(httpClient.close);
  }

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三.請求第三方庫 Dio

1.使用中溫馨提示

1.1.新增依賴

dependencies:
  dio: ^2.0.11 #latest version
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1.2.匯入庫

import 'package:dio/dio.dart';
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2.簡單使用

2.1. GET請求

注意：Dio的get請求（baseUrl都是在dio.option.baseUrl設定的） 請求頭可以在dio.option上設定，也可以在新建的option上設定,新建option是可選的

void loadData_dio_get() async {
    var headers = Map<String, String>();
    headers['loginSource'] = 'IOS';
    headers['useVersion'] = '3.1.0';
    headers['isEncoded'] = '1';
    headers['bundleId'] = 'com.xxx.xxx';
    headers['Content-Type'] = 'application/json';

    Dio dio = Dio();
    dio.options.headers.addAll(headers);
    dio.options.baseUrl = baseUrl;

    Response response = await dio.get(homeNoviceListUrl);

    if (response.statusCode == HttpStatus.ok) {
      print(response.headers);
      print(response.data);
    }
  }
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2.2. POST請求

注意：

dio.options.method設定是無效
Dio dio = Dio();
dio.options.method = 'post';

辦法：
新建一個Options物件，然後在發起請求的時候進行設定：
Options option = Options(method:'post');
Response response = await dio.request(homeRegularListUrl,data:{"currentPage": "1"}, options: option);
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2.2.1. dio - 方式一（baseUrl都是在dio.option.baseUrl設定的）

注意：直接在 dio.options設定除methods以外的 請求頭引數

void loadData_dio_dioOfOptionsSetting() async {
    debugPrint(
        ' \n post請求 ======================= 開始請求 =======================\n');
    var headers = Map<String, String>();
    headers['loginSource'] = 'IOS';
    headers['useVersion'] = '3.1.0';
    headers['isEncoded'] = '1';
    headers['bundleId'] = 'com.xxx.xxx';
    headers['Content-Type'] = 'application/json';

    Dio dio = Dio();
    dio.options.baseUrl = baseUrl;
    dio.options.connectTimeout = 60000;
    dio.options.receiveTimeout = 60000;
    dio.options.headers.addAll(headers);
    dio.options.method = 'post';

    Options option = Options(method: 'post');
    // Response response = await dio.request(homeRegularListUrl,
    //     data: {"currentPage": "1"}, options: option);

    Response response = await dio.post(homeRegularListUrl,
        data: {"currentPage": "1"}, options: option);

    if (response.statusCode == HttpStatus.ok) {
      debugPrint('請求引數： ${response.request.queryParameters}');
      debugPrint(
          '-------------------請求成功,請求結果如下:-----------------\n \n===請求求url: ${response.request.uri.toString()} \n \n===請求 ���:   \n${response.headers} \n \n===請求結果: \n${response.data}\n');
      debugPrint('-------------------請求成功,請求結果列印完畢----------------');
    } else {
      print('請求失敗');
    }
  }
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2.2.2. dio - 方式二（baseUrl都是在dio.option.baseUrl設定的）

注意：在新建的option上設定請求頭引數

void loadData_dio_newOptionSetting() async {
    debugPrint(' \n======================= 開始請求 =======================\n');
    var headers = Map<String, String>();
    headers['loginSource'] = 'IOS';
    headers['useVersion'] = '3.1.0';
    headers['isEncoded'] = '1';
    headers['bundleId'] = 'com.xxx.xxx';
    headers['Content-Type'] = 'application/json';

    Options option = Options(method: 'post');
    option.connectTimeout = 60000;
    option.receiveTimeout = 60000;
    option.headers.addAll(headers);

    Dio dio = Dio();
    dio.options.baseUrl = baseUrl;

    Response response = await dio.post(homeRegularListUrl,
        data: {"currentPage": 1}, options: option);
    // Response response = await dio.request(homeRegularListUrl,
    // data: {"currentPage": 1}, options: option);

    if (response.statusCode == HttpStatus.ok) {
      debugPrint('請求引數： ${response.request.queryParameters}');
      debugPrint(
          '-------------------請求成功,請求結果如下:-----------------\n \n===請求url: ${response.request.uri.toString()} \n \n===請求 頭:   \n${response.headers} \n \n===請求結果: \n${response.data}\n');
      debugPrint('-------------------請求成功,請求結果列印完畢----------------');
    } else {
      print('請求失敗');
    }
  }
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