Flutter JSON配置生成插件json_config_generator的使用

Flutter JSON配置生成插件json_config_generator的使用

1. 整理后的内容中关于“Flutter JSON配置生成插件json_config_generator的使用”的完整示例demo

import 'package:json_config_annotation/json_config_annotation.dart';
import 'dart:convert';
import 'package:flutter/services.dart';

part 'config.g.dart'; //{dart file name}.g.dart

@Configuration(
  environmentEnumName: 'Env',
  environments:[
    Environment(name:'dev', path:'assets/config/dev.json'),
    Environment(name:'prd', path:'assets/config/prd.json'),
  ],
)
class $Config{}

class _CustomClass {
  const _CustomClass({required this.value1, required this.value2});

  factory _CustomClass.fromJson(Map<String, dynamic> customClass) => _CustomClass(
    value1: customClass['value_1'] as String,
    value2: customClass['value_2'] as String,
  );

  final String value1;

  final String value2;
}

class _CustomList {
  const _CustomList({required this.value1});

  factory _CustomList.fromJson(Map<String, dynamic> customList) => _CustomList(
    value1: customList['value_1'] as String,
  );

  final String value1;

  static List<_CustomList> listFromJson(List data) => data.map((e) => _CustomList.fromJson(e as Map<String, dynamic>)).toList();
}

enum Env { dev, prd }

class Config {
  Config._();

  static final instance = Config._();

  late String baseUrl;

  late _CustomClass customClass;

  late int intValue;

  late double doubleValue;

  late bool booleanValue;

  late List<String> stringList;

  late List<int> intList;

  late List<bool> boolList;

  late List<_CustomList> customList;

  Future<void> init(Env env) async {
    String path = '';
    switch (env) {
      case Env.dev:
        path = 'assets/config/dev.json';
        break;
      case Env.prd:
        path = 'assets/config/prd.json';
        break;
    }
    final jsonString = await rootBundle.loadString(path);
    final config = json.decode(jsonString) as Map<String, dynamic>;
    baseUrl = config['base_url'] as String;
    customClass =
        _CustomClass.fromJson(config['custom_class'] as Map<String, dynamic>);
    intValue = config['int_value'] as int;
    doubleValue = config['double_value'] as double;
    booleanValue = config['boolean_value'] as bool;
    stringList = (config['string_list'] as List).cast<String>();
    intList = (config['int_list'] as List).cast<int>();
    boolList = (config['bool_list'] as List).cast<bool>();
    customList = _CustomList.listFromJson(config['custom_list'] as List);
  }
}

void main() async {
  WidgetsFlutterBinding.ensureInitialized();
  await Config.instance.init(Env.dev);
  runApp(const MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter JSON Config Generator',
      home: Scaffold(
        appBar: AppBar(
          title: Text('Flutter JSON Config Generator'),
        ),
        body: Center(
          child: Text(
            'baseUrl: ${Config.instance.baseUrl}\n'
            'customClass.value1: ${Config.instance.customClass.value1}\n'
            'intValue: ${Config.instance.intValue}\n'
            'doubleValue: ${Config.instance.doubleValue}\n'
            'booleanValue: ${Config.instance.booleanValue}\n'
            'stringList: ${Config.instance.stringList.join(', ')}\n'
            'intList: ${Config.instance.intList.join(', ')}\n'
            'boolList: ${Config.instance.boolList.join(', ')}\n'
            'customList: ${Config.instance.customList.map((item) => item.value1).join(', ')}',
          ),
        ),
      ),
    );
  }
}

2. 参考我提供的内容和示例代回答“Flutter JSON配置生成插件json_config_generator的使用”对应的内容

动机

如果你使用JSON文件来配置你的应用程序，也许你需要编写一个包含所有变量及其数据类型的Dart类。当你需要管理嵌套对象时会更加复杂。即使你想在JSON中添加或删除一个值，你也需要修改你的Dart类。

如果你想管理环境，你需要手动为每个需要的环境写入文件路径。

json_config_generator 想要帮助你轻松地处理配置文件和环境的管理。

安装

要使用 json_config_generator，你需要 build_runner/code-generator 设置。首先，通过将它们添加到你的 pubspec.yaml 文件中来安装 build_runner 和 json_config_generator：

dependencies:
  json_config_annotation: ^0.1.0

dev_dependencies:
  build_runner:
  json_config_generator: ^0.1.0

• build_runner 是运行代码生成器的工具
• json_config_generator 是代码生成器
• json_config_annotation 包含用于 json_config_generator 的的注解

如何使用

要使用此生成器，需要创建一个空的配置Dart类，该类以 $ 开头，并使用 Configuration 注解定义你想要拥有的环境。每个环境都有 name 和 path，如果有多个，则生成一个 Enum 来表示环境。你还可以指定这个 Enum 的名称，默认名称是 Environment。此外，还需要添加一些导入。

import 'package:json_config_annotation/json_config_annotation.dart';
import 'dart:convert';
import 'package:flutter/services.dart';

part 'config.g.dart'; //{dart file name}.g.dart

@Configuration(
  environmentEnumName: 'Env',
  environments:[
    Environment(name:'dev', path:'assets/config/dev.json'),
    Environment(name:'prd', path:'assets/config/prd.json'),
  ],
)
class $Config{}

假设你有以下JSON文件：

{
  "base_url": "https://example.com",
  "custom_class": {
    "value_1": "dfgdfgdfgwqrrqwrqweqwe324523b252dghfdhd",
    "value_2": "6Lez7aIaAAAAAN6qZG234c25bv666b7yn5m8m6"
  },
  "int_value": 3,
  "double_value": 3.5,
  "boolean_value": true,
  "string_list": ["hello", "world"],
  "int_list": [1, 23, 5],
  "bool_list": [false, true, true],
  "custom_list": [
    {
      "value_1": "hello"
    },
    {
      "value_1": "world"
    }
  ]
}

生成器会创建：

enum Env { dev, prd }

class Config {
  Config._();

  static final instance = Config._();

  late String baseUrl;

  late _CustomClass customClass;

  late int intValue;

  late double doubleValue;

  late bool booleanValue;

  late List<String> stringList;

  late List<int> intList;

  late List<bool> boolList;

  late List<_CustomList> customList;

  Future<void> init(Env env) async {
    String path = '';
    switch (env) {
      case Env.dev:
        path = 'assets/config/dev.json';
        break;
      case Env.prd:
        path = 'assets/config/prd.json';
        break;
    }
    final jsonString = await rootBundle.loadString(path);
    final config = json.decode(jsonString) as Map<String, dynamic>;
    baseUrl = config['base_url'] as String;
    customClass =
        _CustomClass.fromJson(config['custom_class'] as Map<String, dynamic>);
    intValue = config['int_value'] as int;
    doubleValue = config['double_value'] as double;
    booleanValue = config['boolean_value'] as bool;
    stringList = (config['string_list'] as List).cast<String>();
    intList = (config['int_list'] as List).cast<int>();
    boolList = (config['bool_list'] as List).cast<bool>();
    customList = _CustomList.listFromJson(config['custom_list'] as List);
  }
}

class _CustomClass {
  const _CustomClass({required this.value1, required this.value2});

  factory _CustomClass.fromJson(Map<String, dynamic> customClass) => _CustomClass(
    value1: customClass['value_1'] as String,
    value2: customClass['value_2'] as String,
  );

  final String value1;

  final String value2;
}

class _CustomList {
  const _CustomList({required this.value1});

  factory _CustomList.fromJson(Map<String, dynamic> customList) => _CustomList(
    value1: customList['value_1'] as String,
  );

  final String value1;

  static List<_CustomList> listFromJson(List data) => data.map((e) => _CustomList.fromJson(e as Map<String, dynamic>)).toList();
}