显示我的应用程序上的JSON本地文件的数据

Posted 2023-01-15

我有一个本地JSON文件，我需要在我的应用程序上显示它的一些数据，我尝试了一些解决方案，但没有发生任何事情，我在另一个“更轻”的JSON文件上尝试了以下代码，它有效，但它不适用于我的主JSON文件。

这是我的JSON文件：

  "latitude": 49.241524,
  "longitude": 4.063723,
  "glcParts": [
    
      "id": 1,
      "coordinates": [
        
          "latitude": 49.241527,
          "longitude": 4.063755
        ,
        
          "latitude": 49.241545,
          "longitude": 4.063865
        ,
        
          "latitude": 49.241543,
          "longitude": 4.063995
        ,
        
          "latitude": 49.241537,
          "longitude": 4.064188
        
      ]
    ,
    
      "id": 2,
      "coordinates": [
        
          "latitude": 49.241555,
          "longitude": 4.063413
        ,
        
          "latitude": 49.241571,
          "longitude": 4.063260
        ,
        
          "latitude": 49.241589,
          "longitude": 4.063032
        ,
        
          "latitude": 49.241600,
          "longitude": 4.062884
        
      ]
    
  ],
  "gicParts": [
    
      "detectionZoneId": 1,
      "relevanceZoneId": 2,
      "direction": 0,
      "iviType": 0,
      "roadSign": [
        
          "countryCode": "FR",
          "trafficSignPictogram": 2,
          "pictogramCategoryCode": 
            "nature": 6,
            "serialNumber": 61
          
        
      ],
      "extraText": [
        
          "language": 714,
          "content": "Rétrécissement"
        ,
        
          "language": 714,
          "content": "voie"
        

      ]
    ,
    
      "detectionZoneId": 1,
      "relevanceZoneId": 2,
      "direction": 0,
      "iviType": 1,
      "roadSign": [
        
          "countryCode": "FR",
          "trafficSignPictogram": 2,
          "pictogramCategoryCode": 
            "nature": 5,
            "serialNumber": 57
          
        
      ],
      "extraText": [
        
          "language": 714,
          "content": "/!\\ 50 km/h"
        
      ]
    
  ],
  "timeStamp": "2019-03-08T16:00:00+01:00",
  "validFrom": "2019-03-08T16:00:00+01:00",
  "validTo": "2019-03-08T18:00:00+01:00",
  "countryCode": 714,
  "providerIdentifier": 4201,
  "status": 0

C＃类：

using System;
using System.Collections.Generic;

namespace interface_test

    public class Coordinate
    
        public double latitude  get; set; 
        public double longitude  get; set; 
    

    public class GlcPart
    
        public int id  get; set; 
        public List<Coordinate> coordinates  get; set; 
    

    public class PictogramCategoryCode
    
        public int nature  get; set; 
        public int serialNumber  get; set; 
    

    public class RoadSign
    
        public string countryCode  get; set; 
        public int trafficSignPictogram  get; set; 
        public PictogramCategoryCode pictogramCategoryCode  get; set; 
    

    public class ExtraText
    
        public int language  get; set; 
        public string content  get; set; 
    

    public class GicPart
    
        public int detectionZoneId  get; set; 
        public int relevanceZoneId  get; set; 
        public int direction  get; set; 
        public int iviType  get; set; 
        public List<RoadSign> roadSign  get; set; 
        public List<ExtraText> extraText  get; set; 
    

    public class IVIv2
    
        public double latitude  get; set; 
        public double longitude  get; set; 
        public List<GlcPart> glcParts  get; set; 
        public List<GicPart> gicParts  get; set; 
        public DateTime timeStamp  get; set; 
        public DateTime validFrom  get; set; 
        public DateTime validTo  get; set; 
        public int countryCode  get; set; 
        public int providerIdentifier  get; set; 
        public int status  get; set; 
    

主类：

using System;
using System.Collections.Generic;
using System.IO;
using System.Reflection;
using interface_test;
using Newtonsoft.Json;
using Xamarin.Forms;

namespace interface_test

    public partial class IVI_Display : ContentPage
    
        public IVI_Display()
        
            InitializeComponent();
            GetJsonData();
        
        void GetJsonData()
        
            string jsonFileName = "JsonIVI.json";
            GlcPart ObjContactList = new GlcPart();
            var assembly = typeof(IVI_Display).GetTypeInfo().Assembly;
            Stream stream = assembly.GetManifestResourceStream($"assembly.GetName().Name.jsonFileName");
            using (var reader = new StreamReader(stream))
            
                var jsonString = reader.ReadToEnd();

                //Converting JSON Array Objects into generic list    
                ObjContactList = JsonConvert.DeserializeObject<GlcPart>(jsonString);
            
            //Binding listview with json string     
            listviewGLC.ItemsSource = ObjContactList.coordinates;
        

    

XAML要显示：

 <ListView x:Name="listviewGLC" Grid.Row="1" HorizontalOptions="FillAndExpand" Footer="" HasUnevenRows="True">  
                <ListView.ItemTemplate>  
                    <DataTemplate>  
                        <ViewCell>  
                            <Grid HorizontalOptions="FillAndExpand" Padding="10">  
                                <Grid.RowDefinitions>  
                                    <RowDefinition Height="Auto"/>  
                                    <RowDefinition Height="Auto"/>  


                                </Grid.RowDefinitions>  
                                <Label Text="Binding latitude" HorizontalOptions="StartAndExpand" Grid.Row="0" TextColor="Blue"  FontAttributes="Bold"/>  
                                <Label Text="Binding longitude" HorizontalOptions="StartAndExpand" Grid.Row="0" TextColor="Blue"  FontAttributes="Bold"/>  

                                <BoxView HeightRequest="2" Margin="0,10,10,0" BackgroundColor="Gray" Grid.Row="2" HorizontalOptions="FillAndExpand" />  
                            </Grid>  
                        </ViewCell>  

                    </DataTemplate>  
                </ListView.ItemTemplate>  
            </ListView>  

结果，我希望显示纬度和经度，但我没有得到任何东西

答案

根据你的json，你应该在IVIv2对象中反序列化它而不是在GlcPart中。

替换：ObjContactList = JsonConvert.DeserializeObject<GlcPart>(jsonString);

与：ObjContactList = JsonConvert.DeserializeObject<IVIv2>(jsonString);

那之后你的

listviewGLC.ItemsSource = ObjContactList.GlcPart[0];

使用当前的模型结构，您无法创建包含GlcPart列表中所有值的列表视图。

另一答案

ObjContactList必须是xaml中bind的公共属性

我建议使用一个明确的代码将ViewModel添加到ContentPage类并使用Bindingcontext。

public partial class IVI_Display : ContentPage

    public IVI_DisplayViewModel ViewModel  get; set; 

   public IVI_Display()
   
        ViewModel = new IVI_DisplayViewModel();
        ...
        BindingContext = ViewModel;
       




public class IVI_DisplayViewModel

    public object Coordinates  get; set; 
    ...

在Xaml中使用

<ListView x:Name="listviewGLC" ItemsSource="Binding Coordinates Grid.Row="1" HorizontalOptions="FillAndExpand" Footer="" HasUnevenRows="True">  

始终是一个良好的实践类型清晰的代码。