如何获取Java环境中被用户环境变量覆盖的系统环境变量？

Question

In a windows 7 environment, I have a variable VARA="x" defined under System's enironmental variables and the same variable VARA="y" defined under the user's environmental variables. how do i get the value of VARA as defined in the system's environmental variables section. I always get the user value not the system one. Thanks.

Answer 1

You can't.

System.getenv() returns the value of the environment variables at the time your app launched. How those values were set is irrelevant and inaccessible to the JVM

Answer 2

You'll have to access the registry using JNA .

Advapi32Util.registryGetStringValue(WinReg.HKEY_LOCAL_MACHINE,
    "SYSTEM\\CurrentControlSet\\Control\\Session Manager\\Environment",
    name);

You can also access user variables:

Advapi32Util.registryGetStringValue(WinReg.HKEY_CURRENT_USER,
    "Environment",
    name);

Answer 3

In Java you just type:

 String variable = System.getenv("WINDIR");  
System.out.println(variable); 

and you get the system's environmental variable.

If you want to search for all system's environmental variables:

Map<String, String> variables = System.getenv();  

for (Map.Entry<String, String> entry : variables.entrySet())  
{  
   String name = entry.getKey();  
   String value = entry.getValue();  
   System.out.println(name + "=" + value);  
}