Swing/Preferences のバックアップ(No.21)

public MainPanel(final JFrame frame) {
  super(new BorderLayout());
  this.frame = frame;
  this.prefs = Preferences.userNodeForPackage(getClass());
  frame.addWindowListener(new java.awt.event.WindowAdapter() {
    @Override public void windowClosing(WindowEvent e) {
      saveLocation();
      frame.dispose();
    }
  });
  frame.addComponentListener(new ComponentAdapter() {
    @Override public void componentMoved(ComponentEvent e) {
      if(frame.getExtendedState()==JFrame.NORMAL) {
        Point pt = frame.getLocationOnScreen();
        if(pt.x<0 || pt.y<0) return;
        try{
          pos.setLocation(pt);
        }catch(IllegalComponentStateException icse) {}
      }
    }
    @Override public void componentResized(ComponentEvent e) {
      if(frame.getExtendedState()==JFrame.NORMAL) {
        dim.setSize(getSize());
      }
    }
  });
  exitButton.setAction(new AbstractAction("終了") {
    @Override public void actionPerformed(ActionEvent evt) {
      saveLocation();
      frame.dispose();
    }
  });
  clearButton.setAction(
       new AbstractAction("レジストリなどに保存した値をクリアして終了") {
    @Override public void actionPerformed(ActionEvent evt) {
      try{
        prefs.clear();
        prefs.flush();
      }catch(java.util.prefs.BackingStoreException e) {
        e.printStackTrace();
      }
      frame.dispose();
    }
  });
  int wdim = prefs.getInt(PREFIX+"dimw", dim.width);
  int hdim = prefs.getInt(PREFIX+"dimh", dim.height);
  dim.setSize(wdim, hdim);
  setPreferredSize(dim);

  Rectangle screen = frame.getGraphicsConfiguration().getBounds();
  pos.setLocation(screen.x + screen.width/2  - dim.width/2,
          screen.y + screen.height/2 - dim.height/2);
  int xpos = prefs.getInt(PREFIX+"locx", pos.x);
  int ypos = prefs.getInt(PREFIX+"locy", pos.y);
  pos.setLocation(xpos,ypos);
  frame.setLocation(pos.x, pos.y);
  //......
}
private void saveLocation() {
  prefs.putInt(PREFIX+"locx", pos.x);
  prefs.putInt(PREFIX+"locy", pos.y);
  prefs.putInt(PREFIX+"dimw", dim.width);
  prefs.putInt(PREFIX+"dimh", dim.height);
  try{
    prefs.flush();
  }catch(java.util.prefs.BackingStoreException e) {
    e.printStackTrace();
  }
}