Java's “os.name” for Windows 10?

问题:

In Java, we can see the property value of os.name to know the name of the underlying operating system: System.getProperty("os.name").

For each edition of Windows, it used to return always the exact name of the OS: Windows XP for XP, Windows Vista for Vista, Windows 7 for Seven, Windows 8.1 for 8.1, and so on...

The problem is: I just updated my Windows 8.1 to Windows 10 using the released Microsoft updater, and it seems like this property still remains Windows 8.1:

public class OSTest {
  public static void main(String[] args) {
    System.out.println(System.getProperty("os.name"));
  }
}

How can I create a workaround for this? And, does anyone know if this problem persists if installing a fresh Windows 10 copy - that is, this bug is caused by the Microsoft auto-updater -?

回答1:

This is a known problem JDK-8066504 that has been fixed in upcoming Java 8 update 60.

The reason is GetVersionEx function has changed its behavior since Windows 8.1.

There are multiple possible workarounds, see MSDN article.

The trivial one is to exec cmd.exe /c ver.

The other is to look at the version information of one of the system files, e.g. kernel32.dll.

回答2:

This is definitely a known bug. It occurs because the os.name property gets its value from the GetVersionEx in the source code of the Windows API. GetVersionEx however,

may be altered or unavailable for releases after Windows 8.1

As per Microsoft's official website. Instead, we will need to use the IsWindows10OrGreater found in the Version Helper API functions in the versionhelpers.h file. As you probably guessed though, this file is not a Java file, it is written in C. As a result we need to include it in a somewhat roundabout way. It does take quite a bit of work (you need to program in JNI :/) but this tutorial will help you do it. Another solution is shown in this bug log, and does require less effort.

回答3:

You could also use the .contains() method and just check for the "windows" string maybe along the lines of

if (System.getProperty("os.name").toLowerCase().contains("windows") && System.getProperty("os.name").toLowerCase().contains(windows version here [xp, 7, 8, etc]))){}

If you need the windows version you could check for all versions and then assume 8.1 or 10 to move around the bug.

if (System.getProperty("os.name").toLowerCase().contains("windows") && System.getProperty("os.name").toLowerCase().contains("xp")){
//code for windows xp }

else if (System.getProperty("os.name").toLowerCase().contains("windows") && System.getProperty("os.name").toLowerCase().contains("vista")){
//code for windows vista

else if (System.getProperty("os.name").toLowerCase().contains("windows") && System.getProperty("os.name").toLowerCase().contains("7")){
//code for windows 7}

else if (System.getProperty("os.name").toLowerCase().contains("windows") && System.getProperty("os.name").toLowerCase().contains("8")){
//code for windows 8}
else if (System.getProperty("os.name").toLowerCase().contains("windows") && System.getProperty("os.name").toLowerCase().contains("8.1")){
//code for both windows 8.1 and 10

}

Now to explain what is going on here:

1. the if statement is just a conditional to determine the version of windows

2. The System.getProperty("os.name") returns the name of the os as a string

3. The .toLowerCase() method makes that returned String lower case

4. The .contains(String) method checks if the given input string is contained in the String it is being called on

5. The last statement allows for different code for each os except 8.1 & 10 which would need to be handled as one block :(