分步画图

要画出图像一定要重写public void paint(Graphics g)方法，分步画图是将单个图形画在单独的Panel上，定义一个public void draw(Graphics g)方法并调用，然后在Frame中统一画出

public class PersonTest extends Frame {
	Graphics g;	
	List<Part> parts = new ArrayList<Part>();
	public void lanch() {
		setTitle("Person");
		setSize(400,400);
		addWindowListener(new WindowAdapter() {
			@Override
			public void windowClosing(WindowEvent e) {
				setVisible(false);
				System.exit(0);
			}
		});
		setLocation(150,150);
		setVisible(true);
		//创建一个新的图形类，如在窗体显示前调用的话为null
		g = getGraphics();
		director(g);
	}
	
	public void director(Graphics g) {
		Part p1 = new Part(50,50,50,100);
		Part p2 = new Part(50,50,100,50);
		Part p3 = new Part(100,50,100,100);
		Part p4 = new Part(50,100,100,100);
		parts.add(p1);
		parts.add(p2);
		parts.add(p3);
		parts.add(p4);
	}
	
	@Override
	public void paint(Graphics g) {
		if(parts.size() != 0) {
			for(Part p : parts) {
				p.draw(g);
			}
		}
		System.out.println("paint");
	}
	
	public static void main(String[] args) {
		new PersonTest().lanch();
	}
	
	//内部静态类，继承Panel并定义draw方法
	private static class Part extends Panel {
		private int x,y,width,height;
		public Part(int x,int y,int width,int height) {
			this.x = x;
			this.y = y;
			this.width = width;
			this.height = height;
		}
		public void draw(Graphics g) {
			g.drawLine(x, y, width, height);
		}
	} 
}

运行结果：