quadcurve.jsp

提供 精通Java Web动态图表编程 一书的源代码, 大家赶快下载呀

<!--
	Fig. 7.12_02_01: quadCurve.jsp
	功能: 绘制二次曲线
-->
<%@ page language="java" contentType="image/png;charset=GB2312"
	import="java.awt.*"
	import="javax.imageio.*"
	import="java.awt.geom.*"
	import="java.awt.image.*"
%>

<%
		// 清空缓冲区
		response.reset();

		// 注意这里的MIME类型
		response.setContentType("image/png");

		// 创建一个 500X375 的图像
		int width = 500, height = 375;

		BufferedImage image = new BufferedImage(width, height,
			BufferedImage.TYPE_INT_RGB);

		// 创建Java2D对象
		Graphics2D g2d = image.createGraphics();

		// 填充背景
		g2d.setColor(Color.WHITE);
		g2d.fillRect(0, 0, width, height);
		g2d.setColor(Color.BLACK);

		Point2D.Double start, end, control;
		start = new Point.Double(10, 100);
		end = new Point.Double(300, 220);
		control = new Point.Double(170, 10);

		QuadCurve2D.Double quadCurve = new QuadCurve2D.Double
		(
			start.x, start.y, control.x, control.y, end.x, end.y	
		);
		
		Line2D.Double line1 = new Line2D.Double(start, control);
		Line2D.Double line2 = new Line2D.Double(control, end);

		g2d.setPaint(Color.BLUE);
		g2d.draw(line1);
		g2d.draw(line2);

		g2d.setStroke(new BasicStroke(2.0f));
		g2d.setPaint(Color.RED);
		g2d.draw(quadCurve);

		// 部署图形
		g2d.dispose();

		// 利用ImageIO类的write方法对图像进行编码
		ServletOutputStream sos = response.getOutputStream();
		ImageIO.write(image, "PNG", sos);
		sos.close();
%>
<%
/**************************************************************************
 * (C) Copyright 2004-2005 by Jingkui Zhong(钟京馗) and Huan Tang(唐桓).  *
 * All Rights Reserved.                                                   *
 *                                                                        *
 * DISCLAIMER: The authors of this code have used their                   *
 * best efforts in preparing the code. These efforts include the          *
 * development, research, and testing of the theories and programs        *
 * to determine their effectiveness. The authors and publisher make       *
 * no warranty of any kind, expressed or implied, with regard to these    *
 * programs or to the documentation contained in these codes. The authors *
 * shall not be liable in any event for incidental or consequential       *
 * damages in connection with, or arising out of, the furnishing,         *
 * performance, or use of these programs.                                 *
 **************************************************************************/
 %>