我正在阅读这段代码，它正在处理提要 RSS 和 Atom 提要，就像它看起来使用提要数据源类返回 feedsdata 对象一样：
using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Linq;
using System.Threading.Tasks;
using Windows.Web.Syndication;
namespace WindowsBlogReader
{
// FeedData
// Holds info for a single blog feed, including a list of blog posts (FeedItem).
public class FeedData
{
public string Title { get; set; }
public string Description { get; set; }
public DateTime PubDate { get; set; }
private List<FeedItem> _Items = new List<FeedItem>();
public List<FeedItem> Items
{
get
{
return this._Items;
}
}
}
// FeedItem
// Holds info for a single blog post.
public class FeedItem
{
public string Title { get; set; }
public string Author { get; set; }
public string Content { get; set; }
public DateTime PubDate { get; set; }
public Uri Link { get; set; }
}
// FeedDataSource
// Holds a collection of blog feeds (FeedData), and contains methods needed to
// retreive the feeds.
public class FeedDataSource
{
private ObservableCollection<FeedData> _Feeds = new ObservableCollection<FeedData>();
public ObservableCollection<FeedData> Feeds
{
get
{
return this._Feeds;
}
}
public async Task GetFeedsAsync()
{
Task<FeedData> feed1 =
GetFeedAsync("http://blogs.windows.com/skydrive/b/skydrive/atom.aspx");
Task<FeedData> feed2 =
GetFeedAsync("http://blogs.windows.com/windows/b/windowsexperience/atom.aspx");
Task<FeedData> feed3 =
GetFeedAsync("http://blogs.windows.com/windows/b/extremewindows/atom.aspx");
Task<FeedData> feed4 =
GetFeedAsync("http://blogs.windows.com/windows/b/business/atom.aspx");
Task<FeedData> feed5 =
GetFeedAsync("http://blogs.windows.com/windows/b/bloggingwindows/atom.aspx");
Task<FeedData> feed6 =
GetFeedAsync("http://blogs.windows.com/windows/b/windowssecurity/atom.aspx");
Task<FeedData> feed7 =
GetFeedAsync("http://blogs.windows.com/windows/b/springboard/atom.aspx");
Task<FeedData> feed8 =
GetFeedAsync("http://blogs.windows.com/windows/b/windowshomeserver/atom.aspx");
// There is no Atom feed for this blog, so use the RSS feed.
Task<FeedData> feed9 =
GetFeedAsync("http://blogs.windows.com/windows_live/b/windowslive/rss.aspx");
Task<FeedData> feed10 =
GetFeedAsync("http://blogs.windows.com/windows_live/b/developer/atom.aspx");
Task<FeedData> feed11 =
GetFeedAsync("http://blogs.windows.com/ie/b/ie/atom.aspx");
Task<FeedData> feed12 =
GetFeedAsync("http://blogs.windows.com/windows_phone/b/wpdev/atom.aspx");
Task<FeedData> feed13 =
GetFeedAsync("http://blogs.windows.com/windows_phone/b/wmdev/atom.aspx");
Task<FeedData> feed14 =
GetFeedAsync("http://blogs.windows.com/windows_phone/b/windowsphone/atom.aspx");
this.Feeds.Add(await feed1);
this.Feeds.Add(await feed2);
this.Feeds.Add(await feed3);
this.Feeds.Add(await feed4);
this.Feeds.Add(await feed5);
this.Feeds.Add(await feed6);
this.Feeds.Add(await feed7);
this.Feeds.Add(await feed8);
this.Feeds.Add(await feed9);
this.Feeds.Add(await feed10);
this.Feeds.Add(await feed11);
this.Feeds.Add(await feed12);
this.Feeds.Add(await feed13);
this.Feeds.Add(await feed14);
}
private async Task<FeedData> GetFeedAsync(string feedUriString)
{
Windows.Web.Syndication.SyndicationClient client = new SyndicationClient();
Uri feedUri = new Uri(feedUriString);
try
{
SyndicationFeed feed = await client.RetrieveFeedAsync(feedUri);
// This code is executed after RetrieveFeedAsync returns the SyndicationFeed.
// Process the feed and copy the data you want into the FeedData and FeedItem classes.
FeedData feedData = new FeedData();
if (feed.Title != null && feed.Title.Text != null)
{
feedData.Title = feed.Title.Text;
}
if (feed.Subtitle != null && feed.Subtitle.Text != null)
{
feedData.Description = feed.Subtitle.Text;
}
if (feed.Items != null && feed.Items.Count > 0)
{
// Use the date of the latest post as the last updated date.
feedData.PubDate = feed.Items[0].PublishedDate.DateTime;
foreach (SyndicationItem item in feed.Items)
{
FeedItem feedItem = new FeedItem();
if (item.Title != null && item.Title.Text != null)
{
feedItem.Title = item.Title.Text;
}
if (item.PublishedDate != null)
{
feedItem.PubDate = item.PublishedDate.DateTime;
}
if (item.Authors != null && item.Authors.Count > 0)
{
feedItem.Author = item.Authors[0].Name.ToString();
}
// Handle the differences between RSS and Atom feeds.
if (feed.SourceFormat == SyndicationFormat.Atom10)
{
if (item.Content != null && item.Content.Text != null)
{
feedItem.Content = item.Content.Text;
}
if (item.Id != null)
{
feedItem.Link = new Uri(item.Id);
}
}
else if (feed.SourceFormat == SyndicationFormat.Rss20)
{
if (item.Summary != null && item.Summary.Text != null)
{
feedItem.Content = item.Summary.Text;
}
if (item.Links != null && item.Links.Count > 0)
{
feedItem.Link = item.Links[0].Uri;
}
}
feedData.Items.Add(feedItem);
}
}
return feedData;
}
catch (Exception)
{
return null;
}
}
// Returns the feed that has the specified title.
public static FeedData GetFeed(string title)
{
// Simple linear search is acceptable for small data sets
var _feedDataSource = App.Current.Resources["feedDataSource"] as FeedDataSource;
var matches = _feedDataSource.Feeds.Where((feed) => feed != null && feed.Title.Equals(title));
if (matches.Count() == 1) return matches.First();
return null;
}
// Returns the post that has the specified title.
public static FeedItem GetItem(string uniqueId)
{
// Simple linear search is acceptable for small data sets
var _feedDataSource = App.Current.Resources["feedDataSource"] as FeedDataSource;
var matches = _feedDataSource.Feeds
.Where(group => group != null)
.SelectMany(group => group.Items).Where((item) => item.Title.Equals(uniqueId));
if (matches.Count() == 1) return matches.First();
return null;
}
}
}
我的问题是关于任务方法：
public async Task GetFeedsAsync()private async Task<FeedData> GetFeedAsync(string feedUriString)
很明显，第二种方法是从第一种方法重载的，现在我想在这里明确的是我可以处理数据源的方式的这两种实现，以使我的问题更清楚：这是否意味着我们可以使用是提供提要 uri 的第一个 TASK 方法还是使用第二个 TASK 方法，我可以选择使用其中一个？
我希望我能很好地解释我的误解。