执行本实例后，用鼠标拖动选中的小图片进行拼接，可以拼成一幅完整的图片。本实例的知识点有：鼠标事件的监听，Graphics类和Image类的应用。-After the implementation of this example, drag the mouse to select the small pictures stitching, you can makes up a complete picture. Knowledge points in this instance are: mouse event listener, Graphics class and the Image class applications.