这是一个swing等待半透明覆盖层 panel本身并没有被透明化 在覆盖层中可以加入任何控件(子控件不可透明化,否则会变成黑色)-This is a swing to wait translucent cover panel itself was not transparent in the cover layer can be added to any control (a control non-transparent, otherwise it will turn black)