输出随机数字的认证图片

package com.zpc.servlet;import java.awt.Color;import java.awt.Font;import java.awt.Graphics;import java.awt.image.BufferedImage;import java.io.IOException;import java.io.PrintWriter;import java.util.Random;import javax.imageio.ImageIO;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;public class VertifyImageDemo extends HttpServlet {public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {//5、设置浏览器content-type头信息，以何种方式打开response.setContentType("image/jpeg");//6、设置缓存信息response.setHeader("Expires", "-1");response.setHeader("Cache-COntrol", "no-cache");response.setHeader("Pragma", "no-cache");//1、内存你中创建图片BufferedImage image = new BufferedImage(80, 20,BufferedImage.TYPE_INT_RGB);//2、得到图片Graphics graphics = image.getGraphics();//3、设置图片信息graphics.setColor(Color.RED);graphics.setFont(new Font(null,Font.BOLD,20));graphics.drawString(makeStr(),0, 20);//4、写给浏览器ImageIO.write(image, "jpg", response.getOutputStream());}private String makeStr() {//产生7位数字Random random = new Random();String num = random.nextInt(999999)+"";StringBuffer sb = new StringBuffer();for(int i=0;i<7-num.length();i++){sb.append("0");}num = sb.toString()+num;return num;}public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {doGet(request,response);}}