僅當文件存在時才加載資源字典

Question

只有在資源文件存在的情況下才有加載資源字典的方法嗎？ 在下面的情況下，我只希望讓資源字典當文件「資源/ AdditionalStyles.xaml」存在

<ResourceDictionary> 
      <ResourceDictionary.MergedDictionaries> 
       <ResourceDictionary Source="Resources/Styles.xaml" /> 
       <ResourceDictionary Source="Resources/AdditionalStyles.xaml" /> 
      </ResourceDictionary.MergedDictionaries> 

Answer 1

您可以覆蓋OnStartup方法在App.xaml.cs，然後檢查該文件的存在，加載它，如果它存在：

protected override void OnStartup(StartupEventArgs e) 
{ 
    var fileName = Environment.CurrentDirectory() + @"\Resources\AdditionalStyles.xaml"; 

    // Check if the AdditionalStyles.xaml file exists 
    if (File.Exists(fileName) 
    { 
     try 
     { 
      // try and load the file as a dictionary and add it the dictionaries 
      var additionalStylesDict = (ResourceDictionary)XamlReader.Load(fs); 
      Resources.MergedDictionaries.Add(additionalStylesDict); 
     } 
     catch (Exception ex) 
     { 
      // something went wrong loading the resource file 
     } 
    } 

    // any other stuff on startup 

    // call the base method 
    base.OnStartup(e); 
} 

Answer 2

您可以通過動態加載它通過代碼，而不是在App.xaml中插入類似的參考嘗試有人試圖做：Dynamically loading resource dictionary files to a wpf application gives an error

如果我沒有弄錯，它應該會給出一個異常，如果所述資源不存在，你可以捕獲該錯誤，或​​者檢查文件是否存在於路徑XYZ中，並執行其他邏輯你想繼續：

var foo = new Uri("pack://siteoforigin:,,,/resources/leaf_styles.xaml", UriKind.RelativeOrAbsolute); 
Application.Current.Resources.MergedDictionaries.Add(new ResourceDictionary() { Source = foo }); 

Answer 3

加載動態：

private void LoadDynamicResource(String sStyle) 
    { 
     FileInfo fi1 = new FileInfo(sStyle); 
     if(fi1.Exists) 
     { 
      using (FileStream fs = new FileStream(sStyle, FileMode.Open)) 
      { 
       ResourceDictionary dic = (ResourceDictionary)XamlReader.Load(fs); 
       Resources.MergedDictionaries.Clear(); 
       Resources.MergedDictionaries.Add(dic); 
      } 
     } 
    }