Windows Phone 8:从 Web 读取 XML [英] Windows Phone 8: Reading XML from Web

问题描述

作为一个项目的一部分，我正在尝试加载这个 XML 页面(http://weather.yahooapis.com/forecastrss?w=2459115) 到我的 Windows Phone 8 应用程序中，并将多个值保存为变量.

As part of a project i am working on i am trying to load this XML page (http://weather.yahooapis.com/forecastrss?w=2459115) into my Windows Phone 8 application and save the a number of the values as variables.

我使用的是 Visual Studio 2012 专业版和 VB.net.

I am using Visual Studio 2012 professional and VB.net.

到目前为止，我已经搜索并尝试了多种方法，只是试图保存一个变量，但我无法读取它.

So far i have searched and tried a number of ways just trying to save one variable to start with but i am unable to get it to read.

这是我目前所拥有的

Partial Public Class MainPage
Inherits PhoneApplicationPage
Private XMLHANDLE As WebClient

Dim lang As String

Public Sub New()
    InitializeComponent()

    SupportedOrientations = SupportedPageOrientation.Portrait Or SupportedPageOrientation.Landscape


    Dim XML As String = "http://weather.yahooapis.com/forecastrss?w=2459115"
    XMLHANDLE = New WebClient()
    XMLHANDLE.DownloadStringAsync(New Uri(XML))

    AddHandler XMLHANDLE.DownloadStringCompleted, AddressOf XMLHANDLE_DownloadStringCompleted
    AddHandler XMLHANDLE.DownloadProgressChanged, AddressOf XMLHANDLE_DownloadProgressChanged
End Sub


Private Sub XMLHANDLE_DownloadProgressChanged(sender As Object, e As DownloadProgressChangedEventArgs)

End Sub


Private Sub XMLHANDLE_DownloadStringCompleted(sender As Object, e As DownloadStringCompletedEventArgs)
    If e.[Error] Is Nothing AndAlso Not e.Cancelled Then
        Dim resultElements As XElement = XElement.Parse(e.Result)


        lang = resultElements.Element("language").Value
        Console.WriteLine(lang)
    End If

End Sub

我的代码一直在这一行上查找空值异常

My code keeps Finding a null value exception on this line

lang = resultElements.Element("language").Value

推荐答案

Element 只查看当前元素的直接子元素，所以你不能得到 language 元素很简单.

Element looks only over direct children of current element, so you can't get language element that simple.

试试:

lang = resultElements.Element("channel").Element("language").Value

或者使用Descendants方法:

lang = resultElements.Descendants("language").First().Value

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