dart - Flutter:读取文件，解析为 JSON，然后转换为对象以使用点表示法

Question

我正在尝试找到一种方法来读取以特定格式保存数据的文件，将其解析为 JSON，然后将其转换为对象，以便我可以使用点表示法。这里的问题是使用点符号，因为它只返回 null

核心数据.dart

import 'dart:convert';
import 'dart:io';
import 'dart:async';
import 'package:path_provider/path_provider.dart';

@proxy
class CoreObject {
  Map _data;

  CoreObject([String source]) {
    Map json = (source == null) ? new Map() : JSON.decode(source);
    _data = new Map.from(json);
    json.forEach((k, v) {
      print(k);
      _data[k] = v;
    });
  }

  static encode(List<CoreObject> list) {
    String result = "";
    for (CoreObject item in list) {
      result += "${item.toString()};";
    }
    return result;
  }

  @override toString() {
    print(this._data);
    return JSON.encode(this._data);
  }

  @override
  noSuchMethod(Invocation invocation) {
    var name = invocation.memberName.toString().replaceFirst('Symbol(\"', "");
    print("_data.keys ${_data.keys}");
    print("_data.values ${_data.values}");
    if (invocation.isGetter) {
      print("name ${name.replaceAll("\")", "")}");
      var ret = _data[name.replaceAll("\")", "")];
      print("ret $ret");
      print(ret.toString());
      return ret;
    }
    if (invocation.isSetter) {
      _data[name.replaceAll("=\")", "")] = invocation.positionalArguments.first;
    } else {
      super.noSuchMethod(invocation);
    }
  }
}

class Person extends CoreObject {
  Person([source]): super(source);
  @override noSuchMethod(Invocation invocation) {
    super.noSuchMethod(invocation);
  }
}

class CoreContainer {
  String _object;
  var returnNew;
  var path;

  _map(String source) {
    var result = [];
    for (var line in source.split(";")) {
      // print("line $line");
      if (line != "") result.add(returnNew(line));
    }
    print("result $result");
    return result;
  }

  encode(List<CoreObject> list) {
    // print("list $list");
    String result = "";
    list.forEach((CoreObject item) {
      // print("item ${item.toString()}");
      result += "${item};";
    });
    // print("result $result");
    return result;
  }

  CoreContainer(this._object, this.returnNew);

  Future<File> _getFile() async {
    String dir = path ?? (await getApplicationDocumentsDirectory()).path;
    this.path = dir;
    return new File('$dir/$_object.txt');
  }

  Future<List<CoreObject>> getAll() async {
    return _getFile().then((File file) {
      String contents = file.readAsStringSync();
      print("contents $contents");
      return this._map(contents);
    })
    .catchError((Error error) {
      print('error: $error');
      _getFile().then((File file) {
        file.writeAsStringSync("");
      });

      return [];
    });
  }

  save(List<CoreObject> data) async {
    _getFile().then((file) {
      try {
        file.writeAsStringSync(this.encode(data));
      }
      catch (error) {
        print("error: $error");
      }
    }).catchError((Error error) {
      print("error: $error");
    });
  }

  clear() async {
    return _getFile().then((file) {
      file.writeAsStringSync("");
    }).catchError((Error error) {
      print("error: $error");
    });
  }

  Future<List<CoreObject>> get(query) async {
    return this.getAll().then((List data) {
      data.retainWhere(query);
      return data;
    }).catchError((error) {
      print("error: $error");
    });    
  }

  Future<List<CoreObject>> remove(query) async {
    return this.getAll().then((List data) {
      // print(data);
      data.removeWhere(query);
      save(data);
      return data;
    }).catchError((error) {
      print("error: $error");
    });
  }

  Future<List<CoreObject>> add(obj) async {
    return this.getAll().then((data) {
      data.add(obj);
      return save(data).then(() {
        return data;
      })
      .catchError((Error error) {
        throw error;
      });
    }).catchError((Error error) {
      print("error: $error");
    });
  }

}

使用它:

CoreContainer corePerson = new CoreContainer("Person", (source) => new Person(source));

corePerson.getAll().then((List<CoreObject> array) {
  var tempItems = [];
  var i = 0;
  print("array $array");
  while (i < array.length) {
    Person person = array[i];
    print(person); //{"name":"<whatever 'i' is>"}
    print(person.name); //null
    tempItems.add(new ListTile(
      title: new Text("$i"),
      subtitle: new Text("${person.name}"),
    ));
    i++;
  }
  print(tempItems.length);
  count = tempItems.length;
  setState(() {
    items = tempItems;
  });
}).catchError((Error error) {
  print("error: $error, ${error.stackTrace}");
});

Answer 1

由于大量的print 调试，代码很难阅读。

但我想您需要一种将 JSON 数据转换为 Dart 类的方法。

您应该使用像 jaguar_serializer 这样的库来完成这项工作。

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