我正在使用Retrofit for Android.通过基于REST的Web服务可以轻松检索和上载JSON.我们可以在Flutter中获得任何相当于Web服务Retrofit的库吗？

解决方法:

如何在Flutter中发出HTTP请求

这个答案讲述了如何使用Dart团队使用http package发出HTTP请求.如果需要更高级的功能,请查看注释中提到的Dio package.

我们将使用JSONPlaceholder作为以下API示例的目标.

GET     /posts
GET     /posts/1
GET     /posts/1/comments
GET     /comments?postId=1
GET     /posts?userId=1
POST    /posts
PUT     /posts/1
PATCH   /posts/1
DELETE  /posts/1

设定

在pubspec.yaml中添加http包依赖项.

dependencies:
  http: ^0.12.0+1

GET请求

_makeGetRequest() async {

  // make request
  Response response = await get('https://jsonplaceholder.typicode.com/posts');

  // sample info available in response
  int statusCode = response.statusCode;
  Map<String, String> headers = response.headers;
  String contentType = headers['content-type'];
  String json = response.body;

  // TODO convert json to object...

}

替换/发布/ posts / 1以及上面提到的其他GET请求.使用posts返回一个JSON对象数组,而/ posts / 1返回一个JSON对象.您可以使用dart:convert将原始JSON字符串转换为对象.

POST请求

_makePostRequest() async {

  // set up POST request arguments
  String url = 'https://jsonplaceholder.typicode.com/posts';
  Map<String, String> headers = {"Content-type": "application/json"};
  String json = '{"title": "Hello", "body": "body text", "userId": 1}';

  // make POST request
  Response response = await post(url, headers: headers, body: json);

  // check the status code for the result
  int statusCode = response.statusCode;

  // this API passes back the id of the new item added to the body
  String body = response.body;
  // {
  //   "title": "Hello",
  //   "body": "body text",
  //   "userId": 1,
  //   "id": 101
  // }

}

PUT请求

PUT请求旨在替换资源或创建它(如果它不存在).

_makePutRequest() async {

  // set up PUT request arguments
  String url = 'https://jsonplaceholder.typicode.com/posts/1';
  Map<String, String> headers = {"Content-type": "application/json"};
  String json = '{"title": "Hello", "body": "body text", "userId": 1}';

  // make PUT request
  Response response = await put(url, headers: headers, body: json);

  // check the status code for the result
  int statusCode = response.statusCode;

  // this API passes back the updated item with the id added
  String body = response.body;
  // {
  //   "title": "Hello",
  //   "body": "body text",
  //   "userId": 1,
  //   "id": 1
  // }

}

PATCH请求

PATCH请求旨在修改现有资源.

_makePatchRequest() async {

  // set up PATCH request arguments
  String url = 'https://jsonplaceholder.typicode.com/posts/1';
  Map<String, String> headers = {"Content-type": "application/json"};
  String json = '{"title": "Hello"}';

  // make PATCH request
  Response response = await patch(url, headers: headers, body: json);

  // check the status code for the result
  int statusCode = response.statusCode;

  // only the title is updated
  String body = response.body;
  // {
  //   "userId": 1,
  //   "id": 1
  //   "title": "Hello",
  //   "body": "quia et suscipit\nsuscipit recusandae... (old body text not changed)",
  // }

}

请注意,传入的JSON字符串仅包含标题,而不包括PUT示例中的其他部分.

删除请求

_makeDeleteRequest() async {

  // post 1
  String url = 'https://jsonplaceholder.typicode.com/posts/1';

  // make DELETE request
  Response response = await delete(url);

  // check the status code for the result
  int statusCode = response.statusCode;

}

认证

虽然我们上面使用的演示站点不需要它,但如果您需要包含身份验证标头,您可以这样做：

基本认证

// import 'dart:convert'

final username = 'username';
final password = 'password';
final credentials = '$username:$password';
final stringToBase64Url = utf8.fuse(base64Url);
final encodedCredentials = stringToBase64Url.encode(credentials);

Map<String, String> headers = {
  HttpHeaders.contentTypeHeader: "application/json", // or whatever
  HttpHeaders.authorizationHeader: "Basic $encodedCredentials",
};

承载(令牌)认证

// import 'dart:io';

final token = 'WIiOiIxMjM0NTY3ODkwIiwibmFtZSI6Ikpv';

Map<String, String> headers = {
  HttpHeaders.contentTypeHeader: "application/json", // or whatever
  HttpHeaders.authorizationHeader: "Bearer $token",
};

有关

> What is the difference between PUT, POST and PATCH?