获取按键代码以及按键修饰符

When a user presses a key combination, I need to get key's code and which modifier keys (Ctrl, Alt, Shift etc) are currently pressed, and choose an appropriate reaction based on that. Is there a cleaner way to do this than the following? (using InputProcessor#keyDown):

public boolean keyDown(int keycode) {
      boolean ctrl, alt, shift, ...;
      if (Gdx.input.isKeyPressed(Input.Keys.LEFT_SHIFT) || Gdx.input.isKeyPressed(Input.Keys.RIGHT_SHIFT)) {
            shift = true;
      } else if (/* same for ctrl */) {
          ctrl = true;
      } else  /* same for other modifiers */ {
          //...
      }
      // Finally, choose an action based on the key combination pressed
      if (shift && keycode == Input.Keys.A) {
          // What to do if Shift+A is pressed
      } else if (/* and so on */) {
          //...     
      }
}

我看到有 Input.Keys.META_* 位掩码，这可能是我需要的，但我没有找到任何关于如何使用这些位掩码的示例.

class MyInputProcesses extends InputProcesses {
  boolean shift = false;
  // etc...

  public boolean keyDown(int keycode) {
    switch(keycode) {
      case Input.Keys.LEFT_SHIFT :
      case Input.Keys.RIGHT_SHIFT:
        shift = true;
        break;
      case Input.Keys.A:
        if(shift) {
          // Do something if Shift+A is pressed
        }
        break;
    }
    // etc...
  }

  public boolean keyUp(int keycode) {
    switch(keycode) {
      case Input.Keys.LEFT_SHIFT :
      case Input.Keys.RIGHT_SHIFT:
        shift = false;
        break;
      // etc...
    }
  }
}