首先jdk的setExtendedState是有bug的，需要先重载JFrame的setExtendedState方法

/**     * Fix the bug "jframe undecorated cover taskbar when maximized". See:     * http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=4737788     *     * @param state     */    @Override    public void setExtendedState(int state) {        if ((state & java.awt.Frame.MAXIMIZED_BOTH) == java.awt.Frame.MAXIMIZED_BOTH) {            Rectangle bounds = getGraphicsConfiguration().getBounds();            Rectangle maxBounds = null;            // Check to see if this is the 'primary' monitor            // The primary monitor should have screen coordinates of (0,0)            if (bounds.x == 0 && bounds.y == 0) {                Insets screenInsets = getToolkit().getScreenInsets(getGraphicsConfiguration());                maxBounds = new Rectangle(screenInsets.left, screenInsets.top, bounds.width - screenInsets.right - screenInsets.left                        , bounds.height - screenInsets.bottom - screenInsets.top);            } else {                // Not the primary monitor, reset the maximized bounds...                maxBounds = null;            }            super.setMaximizedBounds(maxBounds);        }        super.setExtendedState(state);    }

　　

然后，最大化的时候就设置：

setExtendedState(Frame.MAXIMIZED_BOTH);

 

但是，最小化的时候，需要注意，设置成：

super.setExtendedState(Frame.ICONIFIED | getExtendedState());

否则，假如直接设置：super.setExtendedState(Frame.ICONIFIED);

还原的时候Sate在~Frame.ICONIFIED之后成了0，就变成了NORMAL态，这样是不对的。