ServletOutputStream cannot be resolved to a type

<!--
	Fig. 6.04_01: basic.jsp
	功能: JSP 绘制文本和线段
-->
<%@ page language="java" contentType="image/jpeg;charset=GB2312"
	import="java.awt.image.*"
	import="java.awt.*"
	import="javax.imageio.*"
%>

<%
		// 清空缓冲区
		response.reset();

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

		// 创建一个 640X480 的图像
		int width = 640, height = 480;

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

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

		// 绘制文本
		g.setColor(Color.RED);

		// 绘制11条直线
		for (int i = 1; i <= 11; i++)
		{
		  g.drawLine(10, 10, 90, i * 10);
		}

		// 绘制1个三角形
		g.drawLine(160, 10, 110, 110);
		g.drawLine(160, 10, 210, 110);
		g.drawLine(110, 110, 210, 110);

		// 绘制1个矩形
		g.drawLine(230, 10, 230, 110);
		g.drawLine(230, 10, 330, 10);
		g.drawLine(330, 10, 330, 110);
		g.drawLine(230, 110, 330, 110);

		g.setFont(new Font("方正粗宋简体", Font.PLAIN, 25));
		g.drawString("JSP Web图表的绘制", 45, 145);
		
		// 部署图形
		g.dispose();

		// 利用ImageIO类的write方法对图像进行编码
		ServletOutputStream sos = response.getOutputStream();//出错行
		ImageIO.write(image, "JPG", sos);
		sos.close();
%>