在flutter http请求中为所有请求设置默认标头的最佳方法

Question

抱歉，如果这个问题如此基本，但我是新手，最近找不到在 HTTP 请求中设置默认标头的好方法，我可以扩展类或为其包装一个函数，但不应该有一个内置的简单方法，但我在文档中找不到它。

Answer 1

This can be easily made with the Dio package.

https://pub.dartlang.org/packages/dio

Update

Based on the new Dio API:

var dio = Dio();
dio.interceptors.add(InterceptorsWrapper(onRequest: (RequestOptions options) async {
  var customHeaders = {
    'content-type': 'application/json'
    // other headers
  };
  options.headers.addAll(customHeaders);
  return options;
}));

Response response = await dio.get("url");
print(response.data.toString());

Refer the documentation for more details.

Answer 2

import 'package:http/http.dart' as http;

class MyClient extends http.BaseClient{
  http.Client _httpClient = new http.Client();

  MyClient(Map defaultHeaders);

  @override
  Future<http.StreamedResponse> send(http.BaseRequest request) {
    request.headers.addAll(defaultHeaders);
    return _httpClient.send(request);
  }
}

Answer 3

Register custom HttpClientFactory

Dart allows to register a factory for creating an HttpClient

class MyHttpOverrides extends HttpOverrides {
  @override
  HttpClient createHttpClient(SecurityContext context) {
    return new MyHttpClient(super.createHttpClient(context));
  }
}

void main() {
  HttpOverrides.global = new MyHttpOverrides();
  runApp(MyApp());
}

Implement custom HttpClient

Implementing such a custom HttpClient seems overly complicated, but perhaps there is a better way.

The class implements HttpClient from dart:io and all its abstract classes.

The methods get(...) and getUrl(...) are customized to add a custom header using _updateHeaders(...) . You would need to extend that to all other methods like head , headUrl , open , post , ...

import 'dart:io';

class MyHttpClient implements HttpClient {
  HttpClient _realClient;

  MyHttpClient(this._realClient);

  @override
  bool get autoUncompress => _realClient.autoUncompress;

  @override
  set autoUncompress(bool value) => _realClient.autoUncompress = value;

  @override
  Duration get connectionTimeout => _realClient.connectionTimeout;

  @override
  set connectionTimeout(Duration value) =>
      _realClient.connectionTimeout = value;

  @override
  Duration get idleTimeout => _realClient.idleTimeout;

  @override
  set idleTimeout(Duration value) => _realClient.idleTimeout = value;

  @override
  int get maxConnectionsPerHost => _realClient.maxConnectionsPerHost;

  @override
  set maxConnectionsPerHost(int value) =>
      _realClient.maxConnectionsPerHost = value;

  @override
  String get userAgent => _realClient.userAgent;

  @override
  set userAgent(String value) => _realClient.userAgent = value;

  @override
  void addCredentials(
          Uri url, String realm, HttpClientCredentials credentials) =>
      _realClient.addCredentials(url, realm, credentials);

  @override
  void addProxyCredentials(String host, int port, String realm,
          HttpClientCredentials credentials) =>
      _realClient.addProxyCredentials(host, port, realm, credentials);

  @override
  void set authenticate(
          Future<bool> Function(Uri url, String scheme, String realm) f) =>
      _realClient.authenticate = f;

  @override
  void set authenticateProxy(
          Future<bool> Function(
                  String host, int port, String scheme, String realm)
              f) =>
      _realClient.authenticateProxy = f;

  @override
  void set badCertificateCallback(
          bool Function(X509Certificate cert, String host, int port)
              callback) =>
      _realClient.badCertificateCallback = callback;

  @override
  void close({bool force = false}) => _realClient.close(force: force);

  @override
  Future<HttpClientRequest> delete(String host, int port, String path) =>
      _realClient.delete(host, port, path);

  @override
  Future<HttpClientRequest> deleteUrl(Uri url) => _realClient.deleteUrl(url);

  @override
  void set findProxy(String Function(Uri url) f) => _realClient.findProxy = f;

  @override
  Future<HttpClientRequest> get(String host, int port, String path) =>
      _updateHeaders(_realClient.get(host, port, path));

  Future<HttpClientRequest> _updateHeaders(
      Future<HttpClientRequest> httpClientRequest) async {
    return (await httpClientRequest)..headers.add('foo', 'bar');
  }

  @override
  Future<HttpClientRequest> getUrl(Uri url) =>
      _updateHeaders(_realClient.getUrl(url.replace(path: url.path)));

  @override
  Future<HttpClientRequest> head(String host, int port, String path) =>
      _realClient.head(host, port, path);

  @override
  Future<HttpClientRequest> headUrl(Uri url) => _realClient.headUrl(url);

  @override
  Future<HttpClientRequest> open(
          String method, String host, int port, String path) =>
      _realClient.open(method, host, port, path);

  @override
  Future<HttpClientRequest> openUrl(String method, Uri url) =>
      _realClient.openUrl(method, url);

  @override
  Future<HttpClientRequest> patch(String host, int port, String path) =>
      _realClient.patch(host, port, path);

  @override
  Future<HttpClientRequest> patchUrl(Uri url) => _realClient.patchUrl(url);

  @override
  Future<HttpClientRequest> post(String host, int port, String path) =>
      _realClient.post(host, port, path);

  @override
  Future<HttpClientRequest> postUrl(Uri url) => _realClient.postUrl(url);

  @override
  Future<HttpClientRequest> put(String host, int port, String path) =>
      _realClient.put(host, port, path);

  @override
  Future<HttpClientRequest> putUrl(Uri url) => _realClient.putUrl(url);
}

Answer 4

this simple and easy way worked for me

var _dio = Dio();
_dio.options.headers= {"Authorization" : token};

Answer 5

Just expanding on @Radek Manasek idea of a custom Client , I'm overriding all the methods so you don't have to write them again.

import 'dart:convert';

import 'package:http/http.dart' as http;
import 'package:http/http.dart';

class MyClient extends http.BaseClient {
  final Map<String, String> _defaultHeaders;
  http.Client _httpClient = http.Client();

  MyClient(this._defaultHeaders);

  @override
  Future<http.StreamedResponse> send(http.BaseRequest request) {
    return _httpClient.send(request);
  }

  @override
  Future<Response> get(url, {Map<String, String> headers}) {
    return _httpClient.get(url, headers: _mergedHeaders(headers));
  }

  @override
  Future<Response> post(url, {Map<String, String> headers, dynamic body, Encoding encoding}) {
    return _httpClient.post(url, headers: _mergedHeaders(headers), body: body, encoding: encoding);
  }

  @override
  Future<Response> patch(url, {Map<String, String> headers, dynamic body, Encoding encoding}) {
    return _httpClient.patch(url, headers: _mergedHeaders(headers), body: body, encoding: encoding);
  }

  @override
  Future<Response> put(url, {Map<String, String> headers, dynamic body, Encoding encoding}) {
    return _httpClient.put(url, headers: _mergedHeaders(headers), body: body, encoding: encoding);
  }

  @override
  Future<Response> head(url, {Map<String, String> headers}) {
    return _httpClient.head(url, headers: _mergedHeaders(headers));
  }

  @override
  Future<Response> delete(url, {Map<String, String> headers}) {
    return _httpClient.delete(url, headers: _mergedHeaders(headers));
  }

  Map<String, String> _mergedHeaders(Map<String, String> headers) =>
      {...?_defaultHeaders, ...?headers};
}

Answer 6

I am creating a singleton class and initilizing dio in it and using it in all my controllers which need to do http requests.

There is 2 ways to add headers in dio client first is

_dio.interceptors.addAll([
      InterceptorsWrapper(
        onRequest: (options, handler) {
          options.headers.addAll({'authorization': 'Bearer $_authToken'});
          handler.next(options);
        },
      ),
      CustomInterceptors(), // your other interceptors
    ]);

and 2nd one is like this

  void setAuthToken(String token) {
    _authToken = token;
    _dio.options.headers['authorization'] = 'Bearer $token';
  }

First method will add headers before making each request so, we can add conditional based on our business logic. so first method is much better then 2nd method.