FeatureSupport.IsPresent 方法

定義

命名空間:: System.Windows.Forms

組件:: System.Windows.Forms.dll

重要

部分資訊涉及發行前產品，在發行之前可能會有大幅修改。 Microsoft 對此處提供的資訊，不做任何明確或隱含的瑕疵擔保。

判斷系統中是否安裝了指定功能。

多載

名稱	Description
IsPresent(Object)	判斷系統中是否已安裝任何指定的功能版本。
IsPresent(Object, Version)	判斷指定的或更新版本的指定功能是否安裝在系統中。
IsPresent(String, String)	判斷系統中是否已安裝任何指定的功能版本。此方法為 `static`。
IsPresent(String, String, Version)	判斷指定的或更新版本的指定功能是否安裝在系統中。此方法為 `static`。

IsPresent(Object)

來源:: FeatureSupport.cs

來源:: FeatureSupport.cs

來源:: FeatureSupport.cs

來源:: FeatureSupport.cs

來源:: FeatureSupport.cs

判斷系統中是否已安裝任何指定的功能版本。

public:
 virtual bool IsPresent(System::Object ^ feature);

public virtual bool IsPresent(object feature);

abstract member IsPresent : obj -> bool
override this.IsPresent : obj -> bool

Public Overridable Function IsPresent (feature As Object) As Boolean

參數

feature: Object

這是你要注意的功能。

傳回

Boolean

true若存在該特徵;否則，。 false

實作

IsPresent(Object)

範例

以下程式碼範例使用 OSFeature 了該特性的 FeatureSupport 實作與查詢 LayeredWindows 。會檢查該版本是否為 null，以判斷該特徵是否存在。結果會顯示在文字框中。此代碼要求已 textBox1 建立並放入表單。

private:
   void LayeredWindows()
   {
      // Gets the version of the layered windows feature.
      Version^ myVersion = OSFeature::Feature->GetVersionPresent(
         OSFeature::LayeredWindows );
      
      // Prints whether the feature is available.
      if ( myVersion != nullptr )
      {
         textBox1->Text = "Layered windows feature is installed.\n";
      }
      else
      {
         textBox1->Text = "Layered windows feature is not installed.\n";
      }

      
      // This is an alternate way to check whether a feature is present.
      if ( OSFeature::Feature->IsPresent( OSFeature::LayeredWindows ) )
      {
         textBox1->Text = String::Concat( textBox1->Text,
            "Again, layered windows feature is installed." );
      }
      else
      {
         textBox1->Text = String::Concat( textBox1->Text,
            "Again, layered windows feature is not installed." );
      }
   }

private void LayeredWindows() {
   // Gets the version of the layered windows feature.
   Version myVersion = OSFeature.Feature.GetVersionPresent(OSFeature.LayeredWindows);

   // Prints whether the feature is available.
   if (myVersion != null)
      textBox1.Text = "Layered windows feature is installed." + '\n';
   else
      textBox1.Text = "Layered windows feature is not installed." + '\n';

   // This is an alternate way to check whether a feature is present.
   if (OSFeature.Feature.IsPresent(OSFeature.LayeredWindows))
      textBox1.Text += "Again, layered windows feature is installed.";
   else
      textBox1.Text += "Again, layered windows feature is not installed.";
}

Private Sub LayeredWindows()
    ' Gets the version of the layered windows feature.
    Dim myVersion As Version = _
       OSFeature.Feature.GetVersionPresent(OSFeature.LayeredWindows)
       
    ' Prints whether the feature is available.
    If (myVersion IsNot Nothing) Then
        textBox1.Text = "Layered windows feature is installed." & _
           ControlChars.CrLf
    Else
        textBox1.Text = "Layered windows feature is not installed." & _
           ControlChars.CrLf
    End If 
    'This is an alternate way to check whether a feature is present.
    If OSFeature.Feature.IsPresent(OSFeature.LayeredWindows) Then
        textBox1.Text &= "Again, layered windows feature is installed."
    Else
        textBox1.Text &= "Again, layered windows feature is not installed."
    End If
End Sub

給繼承者的注意事項

當你從繼承 FeatureSupport時，必須覆寫該 GetVersionPresent(String, String) 方法。當你覆寫這個方法時，檢查你用來做參數 feature 的類別，是否和方法中 IsPresent(String, String) 該參數的類別是同一類。如果兩個 feature 參數不同，你也必須覆蓋 IsPresent(String, String)。

適用於

IsPresent(Object, Version)

來源:: FeatureSupport.cs

來源:: FeatureSupport.cs

來源:: FeatureSupport.cs

來源:: FeatureSupport.cs

來源:: FeatureSupport.cs

判斷指定的或更新版本的指定功能是否安裝在系統中。

public:
 virtual bool IsPresent(System::Object ^ feature, Version ^ minimumVersion);

public virtual bool IsPresent(object feature, Version minimumVersion);

abstract member IsPresent : obj * Version -> bool
override this.IsPresent : obj * Version -> bool

Public Overridable Function IsPresent (feature As Object, minimumVersion As Version) As Boolean

參數

feature: Object

這是你要注意的功能。

minimumVersion: Version

A Version 代表該功能的最低版本號。

傳回

Boolean

true 若該功能存在且其版本號大於或等於指定的最小版本號; false 若此功能未安裝或其版本號低於指定最低數值。

實作

IsPresent(Object, Version)

給繼承者的注意事項

適用於

IsPresent(String, String)

來源:: FeatureSupport.cs

來源:: FeatureSupport.cs

來源:: FeatureSupport.cs

來源:: FeatureSupport.cs

來源:: FeatureSupport.cs

判斷系統中是否已安裝任何指定的功能版本。此方法為 static。

public:
 static bool IsPresent(System::String ^ featureClassName, System::String ^ featureConstName);

public static bool IsPresent(string featureClassName, string featureConstName);

static member IsPresent : string * string -> bool

Public Shared Function IsPresent (featureClassName As String, featureConstName As String) As Boolean

參數

featureClassName: String

用來查詢指定特徵資訊的類別名稱。此類別必須實作該 IFeatureSupport 介面，或繼承自實作該介面的類別。

featureConstName: String

要注意的是該功能的完整名稱。

傳回

Boolean

true 若該特徵存在; false 若指定功能不存在，或包含該功能的產品尚未安裝。

備註

請參閱包含該功能的產品文件，以決定要傳遞給和featureClassNamefeatureConstName參數的名稱。

另請參閱

GetVersionPresent(String, String)

適用於

IsPresent(String, String, Version)

來源:: FeatureSupport.cs

來源:: FeatureSupport.cs

來源:: FeatureSupport.cs

來源:: FeatureSupport.cs

來源:: FeatureSupport.cs

判斷指定的或更新版本的指定功能是否安裝在系統中。此方法為 static。

public:
 static bool IsPresent(System::String ^ featureClassName, System::String ^ featureConstName, Version ^ minimumVersion);

public static bool IsPresent(string featureClassName, string featureConstName, Version minimumVersion);

static member IsPresent : string * string * Version -> bool

Public Shared Function IsPresent (featureClassName As String, featureConstName As String, minimumVersion As Version) As Boolean

參數

featureClassName: String

用來查詢指定特徵資訊的類別名稱。此類別必須實作該 IFeatureSupport 介面，或繼承自實作該介面的類別。

featureConstName: String

要注意的是該功能的完整名稱。

minimumVersion: Version

A Version 代表該功能的最小版本號。

傳回

Boolean

true 若該功能存在且其版本號大於或等於指定的最小版本號; false 若此功能未安裝或其版本號低於指定最低數值。

備註

請參閱包含該功能的產品文件，以決定要傳遞給和featureClassNamefeatureConstName參數的名稱。

另請參閱

GetVersionPresent(String, String)

適用於

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