用户在文本框输入圆的半径，然后随机产生一个坐标位置，在屏幕上画圆，通过其他组件（如：JTextArea)输出圆的直径、周长和面积。另外提供一个按钮，可以清除屏幕，重新画圆。

-Users in the text box input round radius, then randomly generated a coordinate location, on the screen to draw circles, through other components (e.g. JTextArea) output diameter of the circle, ZhouChangHe area. In addition to provide a button, can clear the screen, and to draw circles.