JFrame JDialog透明

         JFrame.setDefaultLookAndFeelDecorated(true );
         SwingUtilities.invokeLater(new  Runnable() {
             public   void  run() {
                 Window w = new  TranslucentWindow();
                 w.setVisible(true );

         //要使窗口透明，您可以使用 AWTUtilities.setWindowOpacity(Window, float) 方法
                 com.sun.awt.AWTUtilities.setWindowOpacity(w, 0 .5f);
             }
          });