[移动开发]flutter中的json转对象

网上有好多json转对象的方法:
在线生成的:https://javiercbk.github.io/json_to_dart/
弊端:每次都要打开网页去生成,尤其是公司网不好的时候,急死;

插件生成的:插件名:FlutterJsonBeanFactory
弊端:不知道没弄明白还是根本没法设置,我只想要一个简单的文件,不要什么继承.
因为子类型总是重复生成.

以下我自己解析json内容生成对象

只涉及到自己用到的类型,如有其他,读者可随时更改

import 'dart:convert';
import 'dart:io';

import 'package:flutter_test/flutter_test.dart';

void main() {
  test('生成实体数据', () async {
    String filePath = "lib/model"; // 生成目录,不带/后缀
    String libraryName = "models"; // 模块名称
    String jsonFile = "models.json"; // json文件
    String entitySuffix = "Entity"; // 实体后缀
    String childTypeFieldName = "_"; // 集合对象,依据对象中的哪个字段获取子类型
    List<Type> constTypes = [String, int, double]; // 常量类型,这些集合类型不做子类处理
    File libraryFile = File("$filePath/index.dart");
    await libraryFile.parent.create();
    String jsonData = await File(jsonFile).readAsString();
    Map<String, dynamic> entities = json.decode(jsonData);
    String parts = "library $libraryName;\n"; // index.dart内容
    for (String fileName in entities.keys) {
      String entityName = fileName; // 实体名称
      String entityContent = "part of $libraryName;\n\n";
      if (entityName.contains("_")) {
        String en = "";
        for (String pre in entityName.split("_")) {
          en += pre.substring(0, 1).toUpperCase() + pre.substring(1);
        }
        entityName = en;
      }
      entityName =
          entityName.substring(0, 1).toUpperCase() + entityName.substring(1);
      entityName += entitySuffix;
      parts += "\npart '$fileName.dart';";

      entityContent += "class $entityName{\n";

      Map<String, dynamic>? entityData = entities[fileName];
      String fields = "";
      String mapToKey = "";
      String keyToMap = "";
      for (String entityKey in entityData!.keys) {
        Type type = entityData[entityKey].runtimeType;
        Type? childType;
        String typeName = "$type";
        String childTypeName = "";
        if (type == List) {
          // 集合类型提取泛型
          childType = entityData[entityKey][0].runtimeType;
          if (constTypes.contains(childType)) {
            typeName = "List<$childType>";
          } else {
            childTypeName =
                entityData[entityKey][0][childTypeFieldName] + entitySuffix;
            // 使用id做子类型
            typeName = "List<$childTypeName>";
          }
        }
        entityContent += "  $typeName? $entityKey;\n"; // 定义变量
        fields += "    this.$entityKey,\n";
        if (childType == null) {
          mapToKey += "\n    $entityKey = json[\"$entityKey\"];";
        } else if (constTypes.contains(childType)) {
          mapToKey += "\n    $entityKey = json[\"$entityKey\"];";
        } else {
          mapToKey += """\n
    if (json["$entityKey"] != null) {
      $entityKey = [];
      json['$entityKey'].forEach((v) {
        $entityKey!.add($childTypeName.forJson(v));
      });
    }\n""";
        }
        if (childType == null) {
          keyToMap += "\n    data['$entityKey'] = $entityKey;";
        } else if (constTypes.contains(childType)) {
          keyToMap += "\n    data['$entityKey'] = $entityKey;";
        } else {
          keyToMap += """\n
    if($entityKey != null) {
      data['$entityKey'] = $entityKey!.map((v) => v.toJson()).toList();
    }\n""";
        }
      }

      // 构造函数
      entityContent += "\n  $entityName({\n$fields  });\n\n";

      // json转对象
      entityContent +=
          "  $entityName.forJson(Map<String,dynamic> json) {$mapToKey\n  }\n\n";
      // 对象转json
      entityContent +=
          "  Map<String,dynamic> toJson(){\n    final Map<String,dynamic> data = {};$keyToMap\n    return data;\n  }\n}";

      File entityFile = File("$filePath/$fileName.dart");
      if (!await entityFile.exists()) {
        entityFile.createSync();
      } else {
        print("重写:$entityFile");
      }
      IOSink out = entityFile.openWrite();
      out.write(entityContent);
      await out.close();
    }

    IOSink out = libraryFile.openWrite();
    out.write(parts);
    out.close();
  });
}

json格式如下

{
"category_type": {
    "id": "",
    "name": "分类菜单",
    "children": [
      {
        "id": "CategoryType"
      }
    ]
  },
  "category": {
    "id": "",
    "categoryId": "",
    "name": "",
    "color": "",
    "image": "",
    "url": "deeplink"
  },
}

生成结果

index.dart
category_type.dart
category.dart

备注说明

1.子数据类型用子数据的_(下划线)值代替
2.有些类型转为json对象时不需要对象转化,有变量constTypes控制,加入即可.