本文介绍如何优雅地封装一个网络库，包含以下几个点：
- JSON转换为实体对象
- 类似Promise方式的API封装
JSON转换为实体对象
第一步，安装json2entity工具
flutter packages pub global activate json2entity
配置启动项：
vim $HOME/.bash_profile
export FLUTTER_HOME=<path to flutter>
export PATH="$PATH:$FLUTTER_HOME/.pub-cache/bin"
第二步，使用json串自动生成Dart实体类
j2e -j '{"result":1,"msg":"ok"}' -o output/BaseEntity
HTTP 封装
封装常用的GET, POST请求
import 'dart:async';
import 'dart:convert' as Convert;
import 'package:http/http.dart' as http;
class HttpRequest {
final baseUrl;
HttpRequest(this.baseUrl);
Future<dynamic> get(String uri, {Map<String, String> headers}) async {
http.Response response = await http.get(baseUrl + uri, headers: headers);
return _processResponse(uri, response);
}
Future<dynamic> post(String uri, dynamic body, {Map<String, String> headers}) async {
http.Response response = await http.post(baseUrl + uri, body: body, headers: headers);
return _processResponse(uri, response);
}
Future<dynamic> _processResponse(String uri, http.Response response) async {
try {
final statusCode = response.statusCode;
final responseBody = response.body;
var result = Convert.jsonDecode(responseBody);
return result;
} on Exception catch (e) {
if (response != null) {
return {"status": response.statusCode, "message": e.toString()};
} else {
return {"status": -1, "message": "网络异常"};
}
}
}
API封装
/*
API统一返回的实体如下:
{
status: 0,
message: "",
data: {}
}
*/
class API {
static const BASE_URL = 'https://xxx.com';
static const CUSTOM_HEADER = {"": ""};
static var _request = HttpRequest(API.BASE_URL);
static Future<dynamic> _get(String uri, {Map<String, String> headers}) async {
if (headers == null) {
headers = Map<String, String>();
}
headers.addAll(CUSTOM_HEADER);
final response = await _request.get(uri, headers: headers);
final status = response['status'];
if (status == 0) { // 成功返回
final data = response['data'];
return data;
} else { // 失败返回
throw FailureResponse(status, response['message']);
}
}
// 获取xx列表
static Future<dynamic> getXXList({int start, int limit}) async {
final data = await _get('/v1/test?start=$start&limit=$limit');
final items = data['items'];
final result = List<Entity>();
for (var item in items) {
final bean = Entity.fromJson(item);
result.add(bean);
}
return result;
}
}
class FailureResponse {
final int status;
final String message;
FailureResponse(this.status, this.message);
@override
String toString() {
return 'status=$status, message=$message';
}
}
类似Promise的方式访问API
API.getXXList(start: 0, limit: 4).then((data) {
// 更新数据
}).catchError((error) {
print(error);
});
