这个问题询问如何在 Windows 中设置路径变量以包含 Java bin 目录，从而允许您在提示符下使用 javac 命令。发布到这个问题的解决方案指出您应该硬编码最新 Java 安装的绝对路径。
在这种情况下，它恰好是c:\program files\java\jdk1.6.0_16\bin
我相信一旦安装了 Java 更新 17、18 及更高版本，您的 javac cmd 仍将使用此旧版本，对吗？
我错过了什么吗？有没有办法将其设置为自动使用最近安装的 java 更新？
问问题
11618 次
3 回答
6
我相信一旦安装了 Java 更新 17、18 及更高版本，您的 javac cmd 仍将使用此旧版本，对吗？
正确的。当java更新时，更新的是JRE（java运行时环境）
这会自动将您的 java 插件（在浏览器中使用）和您的 java 命令设置为最新版本。（打开终端并输入 java -version ）
包含 javac 的 SDK ( Java SDK )不会更改。您必须手动完成。
一种选择是按照 mhaller 所说的去做。
我进一步使用 Windows 中的环境变量。
MyPC/RigthClick/属性/高级/EnvironmentVariables/
从那里我将 JAVA_HOME 添加到所需的 JDK 路径（ c:\jsdk_x_x_x ）并将 PATH 变量设置为：
whatever;_it_had;_before;%JAVA_HOME%\bin
有没有办法将其设置为自动使用最近安装的 java 更新？
对于 JRE，它将自动设置，对于 SDK，您只需修改系统变量并更改JAVA_HOME
于 2009-11-06T22:27:03.453 回答
2
请改用 Java 安装程序设置的变量：
set path="%path%;%JAVA_HOME%\bin"
于 2009-11-06T22:12:55.090 回答
1
以下 Powershell 脚本对此非常有效：
Remove-PathFolders -Folders "*\Java\jdk*" -EnvironmentVariableTarget $([System.EnvironmentVariableTarget]::Machine)
$jdkDp = (Get-ChildItem -Path "C:\Program Files (x86)\Java\jdk*" | Sort-Object name | Select-Object -Last 1).FullName
Add-PathFolders -Folders $($jdkDp + "\bin\") -EnvironmentVariableTarget $([System.EnvironmentVariableTarget]::Machine)
Get-PathFolders -EnvironmentVariableTarget $([System.EnvironmentVariableTarget]::Machine)
其中使用了以下受启发的自定义函数（您可以将所有内容包含在同一UpdateJavaPath.ps1脚本中）：
<#
.SYNOPSIS
Gets the list of folders specified in the Path environment variable.
.PARAMETER EnvironmentVariableTarget
Specifies the "scope" to use when querying the Path environment variable
("Process", "Machine", or "User"). Defaults to "Process" if the parameter is
not specified.
.EXAMPLE
.\Get-PathFolders.ps1
C:\Windows\system32\WindowsPowerShell\v1.0\
C:\Windows\system32
C:\Windows
C:\Windows\System32\Wbem
...
Description
-----------
The output from this example lists each folder in the Path environment variable
for the current process.
.EXAMPLE
.\Get-PathFolders.ps1 User
C:\NotBackedUp\Public\Toolbox
Description
-----------
The output from this example assumes one folder
("C:\NotBackedUp\Public\Toolbox") has previously been added to the user's Path
environment variable.
#>
Function Get-PathFolders() {
param(
[string] $EnvironmentVariableTarget = "Process")
Set-StrictMode -Version Latest
$ErrorActionPreference = "Stop"
[string[]] $pathFolders = [Environment]::GetEnvironmentVariable(
"Path",
$EnvironmentVariableTarget) -Split ";"
If ($pathFolders -ne $null)
{
Write-Output $pathFolders
}
}
<#
.SYNOPSIS
Adds one or more folders to the Path environment variable.
.PARAMETER Folders
Specifies the folders to add to the Path environment variable..
.PARAMETER EnvironmentVariableTarget
Specifies the "scope" to use for the Path environment variable ("Process",
"Machine", or "User"). Defaults to "Process" if the parameter is not specified.
.EXAMPLE
.\Add-PathFolders.ps1 C:\NotBackedUp\Public\Toolbox
#>
Function Add-PathFolders() {
param(
[parameter(Mandatory = $true, ValueFromPipeline = $true)]
[string[]] $Folders,
[string] $EnvironmentVariableTarget = "Process")
begin
{
Set-StrictMode -Version Latest
$ErrorActionPreference = "Stop"
Write-Verbose "Path environment variable target: $EnvironmentVariableTarget"
[bool] $isInputFromPipeline =
($PSBoundParameters.ContainsKey("Folders") -eq $false)
[int] $foldersAdded = 0
[string[]] $pathFolders = [Environment]::GetEnvironmentVariable(
"Path",
$EnvironmentVariableTarget) -Split ";"
[Collections.ArrayList] $folderList = New-Object Collections.ArrayList
$pathFolders | foreach {
$folderList.Add($_) | Out-Null
}
}
process
{
If ($isInputFromPipeline -eq $true)
{
$items = $_
}
Else
{
$items = $Folders
}
$items | foreach {
[string] $folder = $_
[bool] $isFolderInList = $false
$folderList | foreach {
If ([string]::Compare($_, $folder, $true) -eq 0)
{
Write-Verbose ("The folder ($folder) is already included" `
+ " in the Path environment variable.")
$isFolderInList = $true
return
}
}
If ($isFolderInList -eq $false)
{
Write-Verbose ("Adding folder ($folder) to Path environment" `
+ " variable...")
$folderList.Add($folder) | Out-Null
$foldersAdded++
}
}
}
end
{
If ($foldersAdded -eq 0)
{
Write-Verbose ("No changes to the Path environment variable are" `
+ " necessary.")
return
}
[string] $delimitedFolders = $folderList -Join ";"
[Environment]::SetEnvironmentVariable(
"Path",
$delimitedFolders,
$EnvironmentVariableTarget)
Write-Verbose ("Successfully added $foldersAdded folder(s) to Path" `
+ " environment variable.")
}
}
<#
.SYNOPSIS
Removes one or more folders from the Path environment variable.
.PARAMETER Folders
Specifies the folders to remove from the Path environment variable..
.PARAMETER EnvironmentVariableTarget
Specifies the "scope" to use for the Path environment variable ("Process",
"Machine", or "User"). Defaults to "Process" if the parameter is not specified.
.EXAMPLE
.\Remove-PathFolders.ps1 C:\NotBackedUp\Public\Toolbox
#>
Function Remove-PathFolders(){
param(
[parameter(Mandatory = $true, ValueFromPipeline = $true)]
[string[]] $Folders,
[string] $EnvironmentVariableTarget = "Process")
begin
{
Set-StrictMode -Version Latest
$ErrorActionPreference = "Stop"
Write-Verbose "Path environment variable target: $EnvironmentVariableTarget"
[bool] $isInputFromPipeline =
($PSBoundParameters.ContainsKey("Folders") -eq $false)
[int] $foldersRemoved = 0
[string[]] $pathFolders = [Environment]::GetEnvironmentVariable(
"Path",
$EnvironmentVariableTarget) -Split ";"
[Collections.ArrayList] $folderList = New-Object Collections.ArrayList
$pathFolders | foreach {
$folderList.Add($_) | Out-Null
}
}
process
{
If ($isInputFromPipeline -eq $true)
{
$items = $_
}
Else
{
$items = $Folders
}
$items | foreach {
[string] $folder = $_
[bool] $isFolderInList = $false
for ([int] $i = 0; $i -lt $folderList.Count; $i++)
{
#If ([string]::Compare($folderList[$i], $folder, $true) -eq 0)
if (($folderList[$i] -like $folder) -or ($folderList[$i] -eq ""))
{
$isFolderInList = $true
Write-Verbose ("Removing folder ($folderList[$i]) from Path" `
+ " environment variable...")
$folderList.RemoveAt($i)
$i--
$foldersRemoved++
}
}
If ($isFolderInList -eq $false)
{
Write-Verbose ("The folder ($folder) is not specified in the Path" `
+ " list.")
}
}
}
end
{
If ($foldersRemoved -eq 0)
{
Write-Verbose ("No changes to the Path environment variable are" `
+ " necessary.")
return
}
[string] $delimitedFolders = $folderList -Join ";"
[Environment]::SetEnvironmentVariable(
"Path",
$delimitedFolders,
$EnvironmentVariableTarget)
Write-Verbose ("Successfully removed $foldersRemoved folder(s) from Path" `
+ " environment variable.")
}
}
于 2015-11-05T19:37:07.000 回答