C# 从JSON获取数据，存储在IsolatedStorageSettings.ApplicationSettings中，在检索JSON时检索数据

我正在努力做到Windows Phone 8中标题所说的，以下是我的做法：

private async void Application_Launching(object sender, LaunchingEventArgs e)
{
    var settings = IsolatedStorageSettings.ApplicationSettings;
    settings.Add("listofCurrency", await CurrencyHelpers.getJsonCurrency());
}

在CurrencyHelpers中：

    public async static Task<Dictionary<string, double>> getJsonCurrency()
    {
        HttpClient client = new HttpClient();

        string jsonResult = await client.GetStringAsync("http://openexchangerates.org/api/latest.json?app_id=xxxxxxx");

        JSONCurrency jsonData = JsonConvert.DeserializeObject<JSONCurrency>(jsonResult);

        Dictionary<string, double> currencyCollection = new Dictionary<string, double>();

        currencyCollection = jsonData.Rates;

        return currencyCollection;

    }

    public static KeyValuePair<double, double> getStorageCurrencyPairRates(string firstCurrency, string secondCurrency)
    {
        var settings = IsolatedStorageSettings.ApplicationSettings;
        double firstCurrencyRate = 1;
        double secondCurrencyRate = 1;

        Dictionary<string, double> currencyCollection = new Dictionary<string,double>();

        //needs some code here to check if "listofCurrency" already has JSONData stored in it.

        settings.TryGetValue<Dictionary<string,double>>("listofCurrency", out currencyCollection);

        foreach (KeyValuePair<string, double> pair in currencyCollection)
        {
            if (pair.Key == firstCurrency)
            {
                firstCurrencyRate = pair.Value;
            }

            else if (pair.Key == secondCurrency)
            {
                secondCurrencyRate = pair.Value;
            }
         }

        return new KeyValuePair<double, double>(firstCurrencyRate, secondCurrencyRate);          
    }
}

public异步静态任务getJsonCurrency（）
{
HttpClient=新的HttpClient（）；
string jsonResult=await client.GetStringAsync（“http://openexchangerates.org/api/latest.json?app_id=xxxxxxx");
JSONCurrency jsonData=JsonConvert.DeserializeObject（jsonResult）；
Dictionary currencyCollection=新建字典（）；
currencyCollection=jsonData.Rates；
退币托收；
}

当主页加载时，我立即从CurrencyHelpers调用另一个方法：

    public async static Task<Dictionary<string, double>> getJsonCurrency()
    {
        HttpClient client = new HttpClient();

        string jsonResult = await client.GetStringAsync("http://openexchangerates.org/api/latest.json?app_id=xxxxxxx");

        JSONCurrency jsonData = JsonConvert.DeserializeObject<JSONCurrency>(jsonResult);

        Dictionary<string, double> currencyCollection = new Dictionary<string, double>();

        currencyCollection = jsonData.Rates;

        return currencyCollection;

    }

    public static KeyValuePair<double, double> getStorageCurrencyPairRates(string firstCurrency, string secondCurrency)
    {
        var settings = IsolatedStorageSettings.ApplicationSettings;
        double firstCurrencyRate = 1;
        double secondCurrencyRate = 1;

        Dictionary<string, double> currencyCollection = new Dictionary<string,double>();

        //needs some code here to check if "listofCurrency" already has JSONData stored in it.

        settings.TryGetValue<Dictionary<string,double>>("listofCurrency", out currencyCollection);

        foreach (KeyValuePair<string, double> pair in currencyCollection)
        {
            if (pair.Key == firstCurrency)
            {
                firstCurrencyRate = pair.Value;
            }

            else if (pair.Key == secondCurrency)
            {
                secondCurrencyRate = pair.Value;
            }
         }

        return new KeyValuePair<double, double>(firstCurrencyRate, secondCurrencyRate);          
    }
}

public static KeyValuePair getStorageCurrencyPairRates（字符串firstCurrency，字符串secondCurrency）
{
var设置=隔离存储设置。应用设置；
双第一货币兑换率=1；
二次货币兑换率=1；
Dictionary currencyCollection=新建字典（）；
//这里需要一些代码来检查“listofCurrency”中是否已经存储了JSONData。
settings.TryGetValue（“货币列表”，out currencyCollection）；
foreach（currencyCollection中的KeyValuePair对）
{
if（pair.Key==firstCurrency）
{
firstCurrencyRate=pair.Value；
}
else if（pair.Key==secondCurrency）
{
secondCurrencyRate=pair.Value；
}
}
返回新的KeyValuePair（firstCurrencyRate、secondCurrencyRate）；
}
}

---

我的想法是将JSON数据存储到存储器中，然后在可用时立即检索，有什么想法吗？非常感谢您的帮助

您使用wait和async的思维方式是正确的，但是您在页面加载时调用了另一个方法，从而破坏了它的概念。威尔弗雷德·韦所说的也是错误的

正确的方法是在App.xamls.cs中声明事件处理程序，如下所示：

公共事件事件处理程序设置就绪

然后将应用程序_Launching（）方法更改为以下内容：

private async void Application_Launching(object sender, LaunchingEventArgs e)
{
    var settings = IsolatedStorageSettings.ApplicationSettings;
    settings.Add("listofCurrency", await CurrencyHelpers.getJsonCurrency());

    if (SettingsReady!= null)
        SettingsReady(this, true);
}

现在，在MainPage.xaml.cs（构造函数-不在加载时）中，声明要在数据实际准备就绪时调用的回调函数：

    // Constructor
    public MainPage()
    {
        InitializeComponent();

        // Call back functions
        App.SettingsReady += App_SettingsReady;
    }

    void App_SettingsReady(object sender, bool e)
    {
        // Here call your function for further data processing
        getStorageCurrencyPairRates();
    }

我尝试使用while（！settings.Contains（“listofCurrency”）但是线程只是循环通过while循环，等待的方法获取JSON数据从未完成。嗨@George，非常感谢您的帮助！我不得不将事件设置为静态，但在其他方面一切都很好。再次感谢。