如何在WebClient中使用字符串.DownloadStringAsync URL
本文关键字:字符串 DownloadStringAsync URL WebClient | 更新日期: 2023-09-27 18:06:24
我目前有这个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"));
我要做的是使用这个字符串:
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。
的例子:
WebClient Detail = new WebClient();
Detail.DownloadStringCompleted += new
DownloadStringCompletedEventHandler(Detail_DownloadStringCompleted);
Detail.DownloadStringAsync(new Uri("http://api.trademe.co.nz/v1/Listings/" + id +
".xml"));
是否有使用这个字符串在URL如上所示?
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.
}
}
任务的另一种使用方式:
using (WebClient client = new WebClient())
{
result = await client.DownloadStringTaskAsync(urlString);
}
你需要这样做:
WebClient wc = new WebClient();
wc.DownloadStringCompleted += new
DownloadStringCompletedEventHandler(wc_DownloadStringCompleted);
wc.DownloadStringAsync(new Uri("http://api.trademe.co.nz/v1/Listings/" +
id + ".xml"));
void wc_DownloadStringCompleted(object sender, DownloadStringCompletedEventArgs e)
{
string text = e.Result;
// … do something with result.
}
这就是你的文本。
他们在同一个页面上吗?如果是这样,那么可以使id
变量成为类级变量,以便可以从类中的任何地方访问它。或者,您可以将WebClient
部分放入接受字符串的方法中。例如:
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ListboxSelectionChanged
处理程序中,只需调用上述方法。
if(lbi != null)
{
string id = lbi.ListingId.ToString();
DownloadInformation(id);
}
作为旁注,最好将WebClient
设置在方法之外,例如在Page的Loaded
事件中。这样,就不必每次都创建一个新实例。