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如何从dart的Json文件中读取对象并映射到变量?

dart flutter json

Adithya Shetty · 技术社区 · 6 年前

JSON文件如下:

[
    {
        "employee1": {
            "firstName": "Lokesh",
            "lastName": "Gupta",
            "website": "howtodoinjava.com"
        }
    },
    {
        "employee2": {
            "firstName": "Brian",
            "lastName": "Schultz",
            "website": "example.com"
        }
    }
]

0 回复 | 直到 6 年前

Yadu 6 年前

将上面的json列表提供给 json.decode()

var dJson = json.decode(list);
//which results in dJson being a List<dynamic>
//access the first result
var first = dJson[0];
//which gives you a Map because the json.decode maintains the structure of the json given
var employee1 = first["employee1"];
//will give you another Map
var firstName = employee1["firstName"];
//will give you the firstName
print(firstName);//Lokesh

Darsh Shah 6 年前

首先,尝试用您得到的JSON创建一个模型。为样本提供模型,如下所示。

class EmployeeModel {
  Employee1 employee1;

  EmployeeModel({this.employee1});

  EmployeeModel.fromJson(Map<String, dynamic> json) {
    employee1 = json['employee1'] != null
        ? new Employee1.fromJson(json['employee1'])
        : null;
  }

  Map<String, dynamic> toJson() {
    final Map<String, dynamic> data = new Map<String, dynamic>();
    if (this.employee1 != null) {
      data['employee1'] = this.employee1.toJson();
    }
    return data;
  }
}

class Employee1 {
  String firstName;
  String lastName;
  String website;

  Employee1({this.firstName, this.lastName, this.website});

  Employee1.fromJson(Map<String, dynamic> json) {
    firstName = json['firstName'];
    lastName = json['lastName'];
    website = json['website'];
  }

  Map<String, dynamic> toJson() {
    final Map<String, dynamic> data = new Map<String, dynamic>();
    data['firstName'] = this.firstName;
    data['lastName'] = this.lastName;
    data['website'] = this.website;
    return data;
  }
}

然后使用

EmployeeModel employee = EmployeeModel.fromJson(responseJSON);

Sagar Acharya 6 年前

看看我创建的这个例子: 下面是您提供的json。

[
    {
        "employee1": {
            "firstName": "Lokesh",
            "lastName": "Gupta",
            "website": "howtodoinjava.com"
        }
    },
    {
        "employee2": {
            "firstName": "Brian",
            "lastName": "Schultz",
            "website": "example.com"
        }
    }
]

解决方法如下:

import 'dart:convert';

import 'package:flutter/material.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(home: HomePage());
  }
}

class Employee {
  String firstName;
  String lastName;
  String website;

  Employee({this.firstName, this.lastName, this.website});
}

class HomePage extends StatefulWidget {
  @override
  _HomePageState createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> {
  bool _isLoading = false;

  List<Employee> employeeList = List();

  @override
  void initState() {
    super.initState();
    getData();
  }

  getData() async {
    String data =
        await DefaultAssetBundle.of(context).loadString("json/parse.json");

    var jsonData = json.decode(data);

    jsonData.forEach((item) {
      item.forEach((key, value) {
        employeeList.add(Employee(
            firstName: value['firstName'],
            lastName: value['lastName'],
            website: value['website']));
      });
    });

    print(employeeList.length);

    employeeList.forEach((item) {
      print(item.firstName);
      print(item.lastName);
      print(item.website);
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(body: Text(''));
  }
}