Draw2D 有两个重要的包：org.eclipse.draw2d.geometry 和 org.eclipse.draw2d.graph，本文中使用了这两个包。org.eclipse.draw2d.geometry 包有一些有用的类-There are two important Draw2D packages: org.eclipse.draw2d.geometry and org.eclipse.draw2d.graph, this article uses the two package