當前位置: 首頁>>代碼示例>>VB.NET>>正文


VB.NET Environment.SetEnvironmentVariable方法代碼示例

本文整理匯總了VB.NET中System.Environment.SetEnvironmentVariable方法的典型用法代碼示例。如果您正苦於以下問題:VB.NET Environment.SetEnvironmentVariable方法的具體用法?VB.NET Environment.SetEnvironmentVariable怎麽用?VB.NET Environment.SetEnvironmentVariable使用的例子?那麽, 這裏精選的方法代碼示例或許可以為您提供幫助。您也可以進一步了解該方法所在System.Environment的用法示例。


在下文中一共展示了Environment.SetEnvironmentVariable方法的2個代碼示例,這些例子默認根據受歡迎程度排序。您可以為喜歡或者感覺有用的代碼點讚,您的評價將有助於係統推薦出更棒的VB.NET代碼示例。

示例1: Example

Module Example
   Public Sub Main()
      Dim value As String 
      Dim toDelete As Boolean = False
      
      ' Check whether the environment variable exists.
      value = Environment.GetEnvironmentVariable("Test1")
      ' If necessary, create it.
      If value Is Nothing Then
         Environment.SetEnvironmentVariable("Test1", "Value1")
         toDelete = True
         
         ' Now retrieve it.
         value = Environment.GetEnvironmentVariable("Test1")
      End If
      ' Display the value.
      Console.WriteLine($"Test1: {value}")
      Console.WriteLine()
      
      ' Confirm that the value can only be retrieved from the process
      ' environment block if running on a Windows system.
      If Environment.OSVersion.Platform = PlatformID.Win32NT Then
         Console.WriteLine("Attempting to retrieve Test1 from:")
         For Each enumValue As EnvironmentVariableTarget In 
                           [Enum].GetValues(GetType(EnvironmentVariableTarget))
            value = Environment.GetEnvironmentVariable("Test1", enumValue)
            Console.WriteLine($"   {enumValue}: {If(value IsNot Nothing, "found", "not found")}")
         Next
         Console.WriteLine()
      End If

      ' If we've created it, now delete it.
      If toDelete Then 
         Environment.SetEnvironmentVariable("Test1", Nothing)
         ' Confirm the deletion.
         If Environment.GetEnvironmentVariable("Test1") = Nothing Then
            Console.WriteLine("Test1 has been deleted.")
         End If
      End If         
   End Sub
End Module
開發者ID:VB.NET開發者,項目名稱:System,代碼行數:41,代碼來源:Environment.SetEnvironmentVariable

輸出:

Test1: Value1

Attempting to retrieve Test1 from:
Process: found
User: not found
Machine: not found

Test1 has been deleted.

The example displays the following output if run on a Unix-based system:
Test1: Value1

Test1 has been deleted.

示例2: Main

' 導入命名空間
Imports System.Collections
Imports Microsoft.Win32

Module Sample 
    Public Sub Main() 
        ' Environment variable names for default, process, user, and machine targets.
        Dim defaultEnvVar As String = NameOf(defaultEnvVar)
        Dim processEnvVar As String = NameOf(processEnvVar)
        Dim userEnvVar As String = NameOf(userEnvVar)
        Dim machineEnvVar As String = NameOf(machineEnvVar)

        Dim dft As String = NameOf(dft)
        Dim process As String = NameOf(process)
        Dim user As String = NameOf(user)
        Dim machine As String = NameOf(machine)

        ' Set the environment variable for each target.
        Console.WriteLine("Setting environment variables for each target...")
        ' The default target (the current process).
        Environment.SetEnvironmentVariable(defaultEnvVar, dft)
        ' The current process.
        Environment.SetEnvironmentVariable(processEnvVar, process, 
                                           EnvironmentVariableTarget.Process)
        ' The current user.
        Environment.SetEnvironmentVariable(userEnvVar, user, 
                                           EnvironmentVariableTarget.User)
        ' The local machine.
        Environment.SetEnvironmentVariable(machineEnvVar, machine, 
                                           EnvironmentVariableTarget.Machine)
        Console.WriteLine()

        ' Define an array of environment variables.
        Dim envVars As String() = { defaultEnvVar, processEnvVar, userEnvVar, machineEnvVar }
        
        ' Try to get the environment variables from each target.
        ' The default (no specified target).
        Console.WriteLine("Retrieving environment variables from the default target:")
        For Each envVar in envVars
          Dim value = Environment.GetEnvironmentVariable(envVar)
          Console.WriteLine($"   {envVar}: {If(value IsNot Nothing, value, "(none)")}")
        Next
        Console.WriteLine()
        ' The process block.
        Console.WriteLine("Retrieving environment variables from the Process target:")
        For Each envVar in envVars
          Dim value = Environment.GetEnvironmentVariable(envVar, EnvironmentVariableTarget.Process)
          Console.WriteLine($"   {envVar}: {If(value IsNot Nothing, value, "(none)")}")
        Next
        Console.WriteLine()
        ' The user block.
        Console.WriteLine("Retrieving environment variables from the User target:")
        For Each envVar in envVars
          Dim value = Environment.GetEnvironmentVariable(envVar, EnvironmentVariableTarget.User)
          Console.WriteLine($"   {envVar}: {value}")
        Next
        Console.WriteLine()
        ' The machine block.
        Console.WriteLine("Retrieving environment variables from the Machine target:")
        For Each envVar in envVars
          Dim value = Environment.GetEnvironmentVariable(envVar, EnvironmentVariableTarget.Machine)
          Console.WriteLine($"   {envVar}: {value}")
        Next
        Console.WriteLine()

        ' Delete the environment variable for each target.
        Console.WriteLine("Deleting environment variables for each target...")
        ' The default target (the current process).
        Environment.SetEnvironmentVariable(defaultEnvVar, Nothing)
        ' The current process.
        Environment.SetEnvironmentVariable(processEnvVar, Nothing, 
                                           EnvironmentVariableTarget.Process)
        ' The current user.
        Environment.SetEnvironmentVariable(userEnvVar, Nothing, 
                                           EnvironmentVariableTarget.User)
        ' The local machine.
        Environment.SetEnvironmentVariable(machineEnvVar, Nothing, 
                                           EnvironmentVariableTarget.Machine)
    End Sub
End Module
開發者ID:VB.NET開發者,項目名稱:System,代碼行數:80,代碼來源:Environment.SetEnvironmentVariable

輸出:

Setting environment variables for each target...

Retrieving environment variables from the default target:
defaultEnvVar: dft
processEnvVar: process
userEnvVar: user
machineEnvVar: (none)

Retrieving environment variables from the Process target:
defaultEnvVar: dft
processEnvVar: process
userEnvVar: user
machineEnvVar: (none)

Retrieving environment variables from the User target:
defaultEnvVar: (none)
processEnvVar: (none)
userEnvVar: user
machineEnvVar: (none)

Retrieving environment variables from the Machine target:
defaultEnvVar: (none)
processEnvVar: (none)
userEnvVar: (none)
machineEnvVar: machine

Deleting environment variables for each target...

The example displays the following output if run on a Unix-based system:

Setting environment variables for each target...

Retrieving environment variables from the default target:
defaultEnvVar: dft
processEnvVar: process
userEnvVar: (none)
machineEnvVar: (none)

Retrieving environment variables from the Process target:
defaultEnvVar: dft
processEnvVar: process
userEnvVar: (none)
machineEnvVar: (none)

Retrieving environment variables from the User target:
defaultEnvVar: (none)
processEnvVar: (none)
userEnvVar: (none)
machineEnvVar: (none)

Retrieving environment variables from the Machine target:
defaultEnvVar: (none)
processEnvVar: (none)
userEnvVar: (none)
machineEnvVar: (none)

Deleting environment variables for each target...


注:本文中的System.Environment.SetEnvironmentVariable方法示例由純淨天空整理自Github/MSDocs等開源代碼及文檔管理平台,相關代碼片段篩選自各路編程大神貢獻的開源項目,源碼版權歸原作者所有,傳播和使用請參考對應項目的License;未經允許,請勿轉載。