Java Jinput: rescan / reload controllers

问题:

I am using java jinput library to read data from joypad, and I have trouble reloading Controllers, I use this to load them:

public Controller[] findStickControllers() {
    ControllerEnvironment ce =
            ControllerEnvironment.getDefaultEnvironment();

    Controller[] cs = ce.getControllers();

    System.out.println(cs.length); //test

    ArrayList<Controller> sel = new ArrayList<>();

    for (Controller c: cs) {
        if(c.getType() == Type.STICK) {
            sel.add(c);
        }
    }

    return sel.toArray(new Controller[]{});
}

This works fine, but if I disconnect my controller, calling this will find it again, and vice versa (connecting it after the first check will not find it at all).

I have tried to put sleep before the fist lookup, with these results:

1. Controllers are acctually scanned when this method is called first time (not at start of the program)
2. When called again, this always returns same controllers as it returned for the first time.
3. First call will also write warning bellow
4. Even when controller is connected (and works), then disconnected (it will still find it though) and reconnected, it will not work

Warning from point 3: (didn't format well in the list)

WARNING: Found unknown Windows version: Windows 8
Attempting to use default windows plug-in.
Loading: net.java.games.input.DirectAndRawInputEnvironmentPlugin

I am using Win 8, and had same problem on Win 7. I had also tried this with mouse, same results.

How can I acctually reload controllers for the 2nd, 3rd, and so on time?

回答1:

I encountered the same problem. The reason is that the actual hardware scan happens only once for each DefaultControllerEnvironment object. Since the only accessible instantiation is a singleton, it never does another scan.

A simple way to force a hardware scan is to create a new object, but neither the class nor the constructor are public. You can however work around this limitation by calling the constructor via reflection.

Rescan

private static ControllerEnvironment createDefaultEnvironment() throws ReflectiveOperationException {

    // Find constructor (class is package private, so we can't access it directly)
    Constructor<ControllerEnvironment> constructor = (Constructor<ControllerEnvironment>)
        Class.forName("net.java.games.input.DefaultControllerEnvironment").getDeclaredConstructors()[0];

    // Constructor is package private, so we have to deactivate access control checks
    constructor.setAccessible(true);

    // Create object with default constructor
    return constructor.newInstance();
}

Usage

// Be aware that creating a new environment is fairly expensive
Controller[] controllers = createDefaultEnvironment().getControllers();

Remove Windows 8 Warnings

/**
 * Fix windows 8 warnings by defining a working plugin
 */
static {

    AccessController.doPrivileged(new PrivilegedAction<Object>() {
        public Object run() {
            String os = System.getProperty("os.name", "").trim();
            if (os.startsWith("Windows 8")) {  // 8, 8.1 etc.

                // disable default plugin lookup
                System.setProperty("jinput.useDefaultPlugin", "false");

                // set to same as windows 7 (tested for windows 8 and 8.1)
                System.setProperty("net.java.games.input.plugins", "net.java.games.input.DirectAndRawInputEnvironmentPlugin");

            }
            return null;
        }
    });

}

回答2:

If you use the accepted answer, you might want to consider killing the thread that was spawned by the previous environment before setting a new one because it won't be cleaned up otherwise. You can do so by calling something like:

final Set<Thread> threadSet = Thread.getAllStackTraces().keySet();
for (final Thread thread : threadSet) {
  final String name = thread.getClass().getName();
  if (name.equals("net.java.games.input.RawInputEventQueue$QueueThread")) {
    thread.interrupt();
    try {
      thread.join();
    } catch (final InterruptedException e) {
      thread.interrupt();
    }
  }
}

回答3:

The warning is because the last time I updated that code windows 7 wasn't even out IIRC, I'll update it.

The controller reload is a feature that has been requested a number of times, but no-one deems it important enough to spend any time implementing it. If you submit a patch I'll take a look and see about committing it. Until someone finds it important enough to spend the time to write it, it's just a missing feature.

回答4:

I had the same problem before. I add the rescanning feature (for Windows back-end only) and post the patch on Java gaming forum but no ones seem interested in to integrate it.

So if you need it, apply my patch from here: http://www.java-gaming.org/topics/rescan-controllers/24782/msg/224604/view.html#msg224604