我在RSS

Question

我有问题。我编写Windows Phone 8.0应用程序，我在应用程序中看不到任何图片。可能错误在正则表达式中，因为在调试中没有任何匹配

Class MainPage.xaml.cs

string strURL = "https://news.google.com/news?   cf=all&ned=pl_pl&hl=pl&topic=b&output=rss"; // URL of RssFeeds.

和类ImageFromRssText.cs

public class ImageFromRssText : IValueConverter
{
    //  Get images from each SyndicationItem. 
    public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        if (value == null) return null;

        List<ImageItem> listUri = GetHtmlImageUrlList(value.ToString());
        return listUri;
    }

    /// <summary> 
    /// Get the URL of the all pictures from the HTML. 
    /// </summary> 
    /// <param name="sHtmlText">HTML code</param> 
    /// <returns>URL list of the all pictures</returns> 
    public static List<ImageItem> GetHtmlImageUrlList(string sHtmlText)
    {
        // The definition of a regular expression to match img tag. 
        Regex regImg = new Regex(@"<img\b[^<>]*?\bsrc[\s\t\r\n]*=[\s\t\r\n]*[""']?[\s\t\r\n]*(?<imgUrl>[^\s\t\r\n""'<>]*)[^<>]*?/?[\s\t\r\n]*>", RegexOptions.IgnoreCase);

        // The search for a matching string.
        MatchCollection matches = regImg.Matches(sHtmlText);
        int i = 0;
        List<ImageItem> imgUrlList = new List<ImageItem>();




        // Get a list of matches
        foreach (Match match in matches)
        {
            imgUrlList.Add(new ImageItem("img" + i, match.Groups["imgUrl"].Value));
            i++;
        }
        return imgUrlList;
    }

Answer 1

确定。我在第二个项目中以不同的方式写了一点（昨天我写了一个新的项目）。虽然问题是一样的，但它不会加载图片。函数HasImage总是返回false（虽然图片存在时）和variabe Image为null（其余变量都可以）

 public class FeedItemViewModel : System.ComponentModel.INotifyPropertyChanged
{

    // Declaration - Title, Image, Lead, Url

  private string _title;

    public string Title
    {
        get
        {
            return _title;
        }
        set
        {
            _title = value;
            OnPropertyChanged("Title");
        }
    }

    // All from RSS (Image and lead)
    private string _lead;

    public string Lead
    {
        get
        {
            return _lead;
        }
        set
        {
            _lead = value;

            // Load picture
            try
            {
                if (TryParseImageUrl(_lead, out _imageUrl))
                    _imageUrl = _imageUrl.Replace("//", "http://");
            }
            catch { }

            OnPropertyChanged("Lead");
        }
    }

    private string _imageUrl;

    public Uri Image
    {
        get
        {
            if (HasImage)
                return new Uri(_imageUrl, UriKind.RelativeOrAbsolute);

            return null;
        }
    }

    // Check if picture exists
    public bool HasImage
    {
        get
        {
            return (!string.IsNullOrEmpty(_imageUrl) && Uri.IsWellFormedUriString(_imageUrl, UriKind.RelativeOrAbsolute));
        }
    }

    // Download url news
    private string _url;

    public string Url
    {
        get
        {
            return _url;
        }
        set
        {
            _url = value;
            OnPropertyChanged("Url");
        }
    }

    public void OnOpenUrl()
    {
        var wb = new Microsoft.Phone.Tasks.WebBrowserTask();
        wb.Uri = new Uri(_url);
        wb.Show();
    }


    // 3 method parse image
    private static bool TryParseImageUrl(string description, out string result)
    {
        string str = ParseAnyImageInTheDescription(description);

        result = str;
        return (!string.IsNullOrEmpty(str) && Uri.IsWellFormedUriString(str, UriKind.RelativeOrAbsolute));
    }

    private static string ParseAnyImageInTheDescription(string item)
    {
        if (item == null) { return null; }

        return ParseImageUrlFromHtml(item);
    }

    private static string ParseImageUrlFromHtml(string html)
    {
        Match match = new Regex("src=(?:\\\"|\\')?(?<imgSrc>[^>]*[^/].(?:jpg|png|jpeg))(?:\\\"|\\')?").Match(html);
        if ((match.Success && (match.Groups.Count > 1)) && (match.Groups[1].Captures.Count > 0))
        {
            return match.Groups[1].Captures[0].Value;
        }
        return null;
    }


    public event System.ComponentModel.PropertyChangedEventHandler PropertyChanged;

    protected virtual void OnPropertyChanged(string propertyName)
    {
        if (this.PropertyChanged != null)
        {
            this.PropertyChanged(this, new System.ComponentModel.PropertyChangedEventArgs(propertyName));
        }
    }
}