jpegservlet.java

该代码是《JSP应用与开发实例》一书的配套光盘

package com.jspdev.ch7;

import java.awt.image.*; 
import java.awt.*; 

import javax.servlet.*; 
import javax.servlet.http.*; 

import java.io.*; 
import java.util.*; 
import com.sun.image.codec.jpeg.*; 

public class JPEGServlet extends HttpServlet { 
	/**
	 *处理 HTTP Get request 
	 */
	public void doGet(HttpServletRequest request, HttpServletResponse response) 
		throws ServletException, IOException { 
			
			response.setContentType("image/jpeg");//注意这里的MIME类型
			ServletOutputStream out = response.getOutputStream(); 
			//构造一个缓冲的图像。
			BufferedImage image = new BufferedImage(750,30, BufferedImage.TYPE_INT_RGB); 
		    int per=0;
		    try{
		    	
			    per=Integer.parseInt((String)request.getParameter("size"));
		    }
		    catch(Exception e)
		    {
		    	e.printStackTrace();
		    }
		    	
			Graphics graphics = image.getGraphics(); 
			graphics.setColor(Color.green); 
			graphics.fillRect(0, 0, 750, 30); //先画一个长条矩形
			graphics.setColor(Color.yellow); //改变颜色
			graphics.fillRect(0, 0, 750*per/100, 30); //利用参数画矩形
			JPEGImageEncoder encoder =JPEGCodec.createJPEGEncoder(out); 
			encoder.encode(image); 
			out.close(); 
		} 
		
	/**
	 *处理 HTTP Post request ,和doGet一样
	 */
	public void doPost(HttpServletRequest request, HttpServletResponse response) 
		throws ServletException, IOException { 
		doGet(request,response); 
	} 
}