Getting environment variable value in java

问题:

An environment variable has been set in windows machine (windows 7) and trying to get the value of the variable from the following java code. However, it returns a null value.

final String value = System.getenv("PE_CONF_PWD");
System.out.println(value);
//print null

Now if I execute the following code, it throws a security exception that means that the user does not have the variable.

SecurityManager m = new SecurityManager();
m.checkPropertyAccess("PE_CONF_PWD");
// java.security.AccessControlException: access denied ("java.util.PropertyPermission" "PE_CONF_PWD" "read") 

Later I have added permission in the JRE security policy file and add the following entry but still it returns null value.

permission java.lang.RuntimePermission "getenv.PE_CONF_PWD";

回答1:

This code snippet should not return null in order for your problem to be resolved...

final String value = System.getenv("PE_CONF_PWD");