如何在 WebClient.DownloadStringAsync URL 中使用 String [英] How to use String in WebClient.DownloadStringAsync URL
本文介绍了如何在 WebClient.DownloadStringAsync URL 中使用 String的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我的 WebClient URL 目前有这个:
I currently have this for my WebClient URL:
WebClient Detail = new WebClient();
Detail.DownloadStringCompleted += new
DownloadStringCompletedEventHandler(Detail_DownloadStringCompleted);
Detail.DownloadStringAsync(new Uri("http://api.trademe.co.nz/v1/Listings/" +
ListingID.Text + ".xml"));
我想做的是使用这个字符串:
What I want to do is use this string:
void ListBoxSelectionChanged(object sender, SelectionChangedEventArgs args)
{
var lbi = ((sender as ListBox).SelectedItem as TradeItem);
if(lbi != null)
{
string id = lbi.ListingId.ToString();
}
}
作为 WebClient URL 的一部分.
As part of that WebClient URL.
示例:
WebClient Detail = new WebClient();
Detail.DownloadStringCompleted += new
DownloadStringCompletedEventHandler(Detail_DownloadStringCompleted);
Detail.DownloadStringAsync(new Uri("http://api.trademe.co.nz/v1/Listings/" + id +
".xml"));
无论如何要在 URL 中使用这个字符串，如上所示?
Is there anyway to use this string in URL as show above?
完整代码:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Animation;
using System.Windows.Shapes;
using Microsoft.Phone.Controls;
using System.Xml.Linq;
namespace TradeMe_Panorama
{
public partial class MainPage : PhoneApplicationPage
{
// Constructor.
public MainPage()
{
InitializeComponent();
// Set the data context of the listbox control to the sample data.
DataContext = App.ViewModel;
this.Loaded += new RoutedEventHandler(MainPage_Loaded);
}
// Load data for the ViewModel items.
private void MainPage_Loaded(object sender, RoutedEventArgs e)
{
if (!App.ViewModel.IsDataLoaded)
{
App.ViewModel.LoadData();
}
}
private void button1_Click(object sender, RoutedEventArgs e)
{
WebClient Trademe = new WebClient();
Trademe.DownloadStringCompleted += new
DownloadStringCompletedEventHandler(Trademe_DownloadStringCompleted);
Trademe.DownloadStringAsync(new
Uri("http://api.trademe.co.nz/v1/Search/General.xml?search_string=" +
TradeSearch.Text));
progressBar1.IsIndeterminate = true;
progressBar1.Visibility = Visibility.Visible;
}
// Display listing for used general products:
void Trademe_DownloadStringCompleted(object sender,
DownloadStringCompletedEventArgs e)
{
if (e.Error != null)
return;
var r = XDocument.Parse(e.Result);
// Declare the namespace.
XNamespace ns = "http://api.trademe.co.nz/v1";
TradeSearch1.ItemsSource = from TM in r.Root.Descendants(ns +
"Listing").Take(20)
select new TradeItem
{
ImageSource = TM.Element(ns + "PictureHref").Value,
Title = TM.Element(ns + "Title").Value,
Region = TM.Element(ns + "Region").Value,
PriceDisplay = TM.Element(ns + "PriceDisplay").Value,
ListingId = TM.Element(ns + "ListingId").Value,
};
progressBar1.IsIndeterminate = false;
progressBar1.Visibility = Visibility.Collapsed;
}
// Display listing for used Cars.
private void button2_Click(object sender, RoutedEventArgs e)
{
WebClient Motor = new WebClient();
Motor.DownloadStringCompleted += new
DownloadStringCompletedEventHandler(Motor_DownloadStringCompleted);
Motor.DownloadStringAsync(new
Uri("http://api.trademe.co.nz/v1/Search/Motors/Used.xml?search_string=" +
MotorSearch.Text));
progressBar1.IsIndeterminate = true;
progressBar1.Visibility = Visibility.Visible;
}
void Motor_DownloadStringCompleted(object sender,
DownloadStringCompletedEventArgs e)
{
if (e.Error != null)
return;
var r = XDocument.Parse(e.Result);
// Declare the namespace.
XNamespace ns = "http://api.trademe.co.nz/v1";
MotorsListings.ItemsSource = from M in r.Root.Descendants(ns +
"Car").Take(20)
select new TradeItem
{
ImageSource = M.Element(ns + "PictureHref").Value,
Title = M.Element(ns + "Title").Value,
Region = M.Element(ns + "Region").Value,
PriceDisplay = M.Element(ns + "PriceDisplay").Value,
ListingId = M.Element(ns + "ListingId").Value,
};
progressBar1.IsIndeterminate = false;
progressBar1.Visibility = Visibility.Collapsed;
}
//Display specific details of listings:
private void button4_Click(object sender, RoutedEventArgs e)
{
WebClient Detail = new WebClient();
Detail.DownloadStringCompleted += new
DownloadStringCompletedEventHandler(Detail_DownloadStringCompleted);
Detail.DownloadStringAsync(new
Uri("http://api.trademe.co.nz/v1/Listings/" + ListingID.Text +
".xml"));
progressBar1.IsIndeterminate = true;
progressBar1.Visibility = Visibility.Visible;
}
void Detail_DownloadStringCompleted(object sender,
DownloadStringCompletedEventArgs e)
{
if (e.Error != null)
return;
var r = XDocument.Parse(e.Result);
// Declare the namespace.
XNamespace ns = "http://api.trademe.co.nz/v1";
ListingDetails.ItemsSource = from D in r.Descendants(ns +
"ListedItemDetail").Take(20)
select new TradeItem
{
ImageSource = D.Element(ns + "Photos").Element(ns +
"Photo").Element(ns + "Value").Element(ns + "Medium").Value,
Title = D.Element(ns + "Title").Value,
Region = D.Element(ns + "Region").Value,
PriceDisplay = D.Element(ns + "Body").Value,
ListingId = D.Element(ns + "ListingId").Value,
CloseDate = D.Element(ns + "EndDate").Value,
BuyNow = D.Element(ns + "BuyNowPrice").Value,
StartPrice = D.Element(ns + "StartPrice").Value,
};
progressBar1.IsIndeterminate = false;
progressBar1.Visibility = Visibility.Collapsed;
}
public class TradeItem
{
public string Region { get; set; }
public string ListingId { get; set; }
public string PriceDisplay { get; set; }
public string Title { get; set; }
public string ImageSource { get; set; }
public string CloseDate { get; set; }
public string StartPrice { get; set; }
public string BuyNow { get; set; }
}
// Run query string to pass LIstingID to next page.
}
}
推荐答案
他们在同一个页面上吗?如果是这样，那么您可以将 id 变量设为类级变量，以便可以从类中的任何位置访问它.或者，您可以将 WebClient 部分放入接受字符串的方法中.例如:
Are they on the same page? If so, then you can make the id variable a class-level variable so that it can be accessed from anywhere in the class. Alternatively, you could put the WebClient section into a method that accepts a string. For example:
private void DownloadInformation(string id)
{
WebClient Detail = new WebClient();
Detail.DownloadStringCompleted += new DownloadStringCompletedEventHandler(Detail_DownloadStringCompleted);
Detail.DownloadStringAsync(new Uri("http://api.trademe.co.nz/v1/Listings/" + id + ".xml"));
}
然后在那个 ListboxSelectionChanged 处理程序中，只需调用上面的方法.
Then in that ListboxSelectionChanged handler, simply call the above method.
if(lbi != null)
{
string id = lbi.ListingId.ToString();
DownloadInformation(id);
}
作为旁注，最好在方法之外设置 WebClient，例如在页面的 Loaded 事件中.这样，就不必每次都创建一个新实例.
As a side note, it's probably best to have the WebClient set up outside the method, such as in the Page's Loaded event. This way, a new instance won't have to be created each time.
这篇关于如何在 WebClient.DownloadStringAsync URL 中使用 String的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
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