设置JFrame剧中显示

网上查到的一种方法：

    /**
     * 设置整个界面居中显示
     */
    private void setCenterDisplay() {
        Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();
        Dimension frameSize = this.getSize();
        if (frameSize.height > screenSize.height) {
            frameSize.height = screenSize.height;
        }
        if (frameSize.width > screenSize.width) {
            frameSize.width = screenSize.width;
        }

        this.setLocation((screenSize.width - frameSize.width) / 2,
                (screenSize.height - frameSize.height) / 2);
    }

JfreeChart中实现的一种方法，位于jcommon.jar中的org.jfree.ui.RefineryUtilities中：

   /**
     * Positions the specified frame in the middle of the screen.
     *
     * @param frame  the frame to be centered on the screen.
     */
    public static void centerFrameOnScreen(final Window frame) {
        positionFrameOnScreen(frame, 0.5, 0.5);
    }

    /**
     * Positions the specified frame at a relative position in the screen, where 50% is considered
     * to be the center of the screen.
     *
     * @param frame  the frame.
     * @param horizontalPercent  the relative horizontal position of the frame (0.0 to 1.0,
     *                           where 0.5 is the center of the screen).
     * @param verticalPercent  the relative vertical position of the frame (0.0 to 1.0, where
     *                         0.5 is the center of the screen).
     */
    public static void positionFrameOnScreen(final Window frame,
                                             final double horizontalPercent,
                                             final double verticalPercent) {

        final Rectangle s = frame.getGraphicsConfiguration().getBounds();
        final Dimension f = frame.getSize();
        final int w = Math.max(s.width - f.width, 0);
        final int h = Math.max(s.height - f.height, 0);
        final int x = (int) (horizontalPercent * w) + s.x;
        final int y = (int) (verticalPercent * h) + s.y;
        frame.setBounds(x, y, f.width, f.height);

    }