percentjpegservlet.java

《J2EE企业级应用开发》一书的配套源代码

package com.j2eeapp.ch18;
import javax.servlet.*; 
import javax.servlet.http.*; 
import java.io.*; 
import java.util.*; 
import com.sun.image.codec.jpeg.*; 
import java.awt.image.*; 
import java.awt.*; 
public class PercentJPEGServlet extends HttpServlet { 
	//处理 HTTP Get request 
	public void doGet(HttpServletRequest request, HttpServletResponse response) 
		throws ServletException, IOException { 
			response.setContentType("image/jpeg");//设置输出流的格式 
			ServletOutputStream out = response.getOutputStream(); 
			BufferedImage image = new BufferedImage(500,20, BufferedImage.TYPE_INT_RGB); 
			//得到提交的百分比参数
			int per=Integer.parseInt((String)request.getParameter("percent"));
			Graphics g = image.getGraphics(); 
			g.setColor(Color.black); 
			g.fillRect(0, 0, 500, 20); //先画一个长条矩形
			g.setColor(Color.red); //改变颜色
			g.fillRect(0, 0, 500*per/100, 20); //利用参数画矩形
			JPEGImageEncoder encoder =JPEGCodec.createJPEGEncoder(out); 
			encoder.encode(image); 
			out.close(); 
		} 
	//处理 HTTP Post request 
	public void doPost(HttpServletRequest request, HttpServletResponse response) 
		throws ServletException, IOException { 
		doGet(request,response); 
	} 
}