Servlet生成验证码

package com.servlet.验证码;

import java.awt.Color;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.io.OutputStream;
import java.util.Random;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;


public class CheckServlet extends HttpServlet {

    public void servlet(HttpServletRequest request, HttpServletResponse response)
                    throws ServletException, IOException {
            // 画画
            BufferedImage image = new BufferedImage(60, 20,
                            BufferedImage.TYPE_INT_RGB);
            Graphics g = image.getGraphics();
            Random r = new Random();
            g.setColor(new Color(r.nextInt(255), r.nextInt(255), r.nextInt(255)));
            g.fillRect(0, 0, 60, 20);
            // 生成一个随机数，并且画到内存映射对象上
            String str = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
            String number = "";
            for (int i = 0; i < 5; i++) {
                    number += str.charAt(r.nextInt(str.length()));
            }

            HttpSession session = request.getSession();
            session.setAttribute("number", number);
            System.out.println(number);
            g.setColor(new Color(0, 0, 0));
            g.drawString(number, 10, 15);
            // 加一些干扰线
            for (int i = 0; i < 5; i++) {
                    g
                                    .setColor(new Color(r.nextInt(255), r.nextInt(255), r
                                                    .nextInt(255)));
                    g.drawLine(r.nextInt(60), r.nextInt(20), r.nextInt(60), r
                                    .nextInt(20));
            }
            // 2 将图片压缩并输出到客户端
            response.setContentType("image/jpeg");
            OutputStream ops = response.getOutputStream();
            javax.imageio.ImageIO.write(image, "jpeg", ops);
    }

}