从 url 获取 JSON，保存到文件，最后是 CreateActivationService

Question

使用Visual Studio 的 Template Studio 扩展，我生成了一个项目解决方案库，现在尝试在继续呈现页面视图之前使用 HTTP 请求插入应用程序加载过程。

应用xaml.cs

using System;
using Braytech_3.Services;
using Windows.ApplicationModel.Activation;
using Windows.Storage;
using Windows.UI.Xaml;
namespace Braytech_3
{
public sealed partial class App : Application
{
private Lazy<ActivationService> _activationService;
private ActivationService ActivationService
{
get { return _activationService.Value; }
}
public App()
{
InitializeComponent();
APIRequest();
// Deferred execution until used. Check https://msdn.microsoft.com/library/dd642331(v=vs.110).aspx for further info on Lazy<T> class.
_activationService = new Lazy<ActivationService>(CreateActivationService);
}
protected override async void OnLaunched(LaunchActivatedEventArgs args)
{
if (!args.PrelaunchActivated)
{
await ActivationService.ActivateAsync(args);
}
}
protected override async void OnActivated(IActivatedEventArgs args)
{
await ActivationService.ActivateAsync(args);
}
private async void APIRequest()
{
//Create an HTTP client object
Windows.Web.Http.HttpClient httpClient = new Windows.Web.Http.HttpClient();
//Add a user-agent header to the GET request. 
var headers = httpClient.DefaultRequestHeaders;
Uri requestUri = new Uri("https://json_url");
//Send the GET request asynchronously and retrieve the response as a string.
Windows.Web.Http.HttpResponseMessage httpResponse = new Windows.Web.Http.HttpResponseMessage();
string httpResponseBody = "";
try
{
//Send the GET request
httpResponse = await httpClient.GetAsync(requestUri);
httpResponse.EnsureSuccessStatusCode();
httpResponseBody = await httpResponse.Content.ReadAsStringAsync();
APITempSave(httpResponseBody);
}
catch (Exception ex)
{
}
}
private async void APITempSave(string json)
{
StorageFolder tempFolder = ApplicationData.Current.TemporaryFolder;
if (await tempFolder.TryGetItemAsync("APIData.json") != null)
{
StorageFile APIData = await tempFolder.GetFileAsync("APIData.json");
await FileIO.WriteTextAsync(APIData, json);
}
else
{
StorageFile APIData = await tempFolder.CreateFileAsync("APIData.json");
await FileIO.WriteTextAsync(APIData, json);
}
}
private ActivationService CreateActivationService()
{
return new ActivationService(this, typeof(Views.VendorsPage), new Lazy<UIElement>(CreateShell));
}
private UIElement CreateShell()
{
return new Views.ShellPage();
}
}
}

我认为我需要做的是一旦APITempSave()被调用就打电话给_activationService = new Lazy<ActivationService>(CreateActivationService);，但我不确定如何这样做以及最佳实践是什么。

任何指导将不胜感激！

Answer 1

经过进一步调查和熟悉生成的解决方案，以及对等待、异步和任务<>的额外谷歌搜索，我能够将请求作为服务与主题选择器和 ToastNotifications 等项目一起实现。

为了确定当前用户的浅色和深色主题模式，首先调用 ThemeSelector 是要调用的东西之一，因此我能够围绕它对我的服务进行建模并同时调用它。

这显然非常特定于模板工作室生成的代码，但是共享了一些概念，如果其他人将来寻找类似的答案，也许他们会找到这个。

APIRequest.cs (Service(

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Windows.Storage;
namespace Braytech_3.Services
{
public static class APIRequest
{
internal static async Task Request()
{
//Create an HTTP client object
Windows.Web.Http.HttpClient httpClient = new Windows.Web.Http.HttpClient();
//Add a user-agent header to the GET request. 
var headers = httpClient.DefaultRequestHeaders;
Uri requestUri = new Uri("https://json_url");
//Send the GET request asynchronously and retrieve the response as a string.
Windows.Web.Http.HttpResponseMessage httpResponse = new Windows.Web.Http.HttpResponseMessage();
string httpResponseBody = "";
try
{
//Send the GET request
httpResponse = await httpClient.GetAsync(requestUri);
httpResponse.EnsureSuccessStatusCode();
httpResponseBody = await httpResponse.Content.ReadAsStringAsync();
await APITempSave(httpResponseBody);
}
catch (Exception ex)
{
}
}
internal static async Task APITempSave(string json)
{
StorageFolder tempFolder = ApplicationData.Current.TemporaryFolder;
if (await tempFolder.TryGetItemAsync("APIData.json") != null)
{
StorageFile APIData = await tempFolder.GetFileAsync("APIData.json");
await FileIO.WriteTextAsync(APIData, json);
}
else
{
StorageFile APIData = await tempFolder.CreateFileAsync("APIData.json");
await FileIO.WriteTextAsync(APIData, json);
}
}
}
}

ActiviationService.cs(最初由 App.xaml.cs 调用(

private async Task InitializeAsync()
{
await ThemeSelectorService.InitializeAsync();
await APIRequest.Request();
}