在Java的GUI组件中，每一个视图都有一个paint方法，这个方法负责组件的绘制，其中会传入Graphics对象参数，开发者可以在paint方法中操作这个对象进行自定义图形的绘制。示例如下：
class DrawPanel extends Panel{
private static final long serialVersionUID = 1L;
public DrawPanel() {
super();
}
@Override
public void paint(Graphics g) {
// TODO Auto-generated method stub
super.paint(g);
Color bg = Color.WHITE;
Color fg = Color.RED;
//绘制背景
g.setColor(bg);
g.draw3DRect(50, 50, 699, 140, true);
g.draw3DRect(53, 53, 692, 133, true);
g.setColor(fg);
//绘制线
g.drawLine(60, 60, 140, 60);
//绘制矩形
g.drawRect(150, 60, 80, 50);
//绘制圆角矩形
g.drawRoundRect(240, 60, 80, 50, 25, 25);
//绘制椭圆
g.drawOval(330, 60, 80, 50);
//绘制弧线
g.drawArc(420, 60, 50, 50, 0, 90);
//绘制闭合折线
Polygon polygon = new Polygon();
polygon.addPoint(510, 60);
polygon.addPoint(550, 60);
polygon.addPoint(550, 110);
polygon.addPoint(590, 110);
g.drawPolygon(polygon);
//填充矩形
g.fillRect(600, 60, 80, 50);
//填充3D矩形
g.fill3DRect(60, 120, 80, 50, true);
//填充圆角矩形
g.fillRoundRect(150, 120, 80, 50, 25, 25);
//填充椭圆
g.fillOval(240, 120, 80, 50);
//填充弧线
g.fillArc(330, 120, 50, 50, 0, 90);
//填充闭合折线
Polygon polygon2 = new Polygon();
polygon2.addPoint(390, 120);
polygon2.addPoint(440, 120);
polygon2.addPoint(440, 180);
polygon2.addPoint(490, 180);
g.fillPolygon(polygon2);
//绘制文字
g.drawString("finish draw test!", 500, 150);
}
}
效果如下图：
