使用jsp编写的验证码(工具类)

<%@ page language="java" contentType="text/html; charset=UTF-8"    pageEncoding="UTF-8"%><%@ page import="java.util.Random"%><%@ page import="java.io.OutputStream"%><%@ page import="java.awt.Color"%><%@ page import="java.awt.Font"%><%@ page import="java.awt.Graphics"%><%@ page import="java.awt.image.BufferedImage"%><%@ page import="javax.imageio.ImageIO"%><%    int width = 60;    int height = 32;    //create the image    BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);    Graphics g = image.getGraphics();    // set the background color    g.setColor(new Color(0xDCDCDC));    g.fillRect(0, 0, width, height);    // draw the border    g.setColor(Color.black);    g.drawRect(0, 0, width - 1, height - 1);    // create a random instance to generate the codes    Random rdm = new Random();    String hash1 = Integer.toHexString(rdm.nextInt());    System.out.print(hash1);    // make some confusion    for (int i = 0; i < 50; i++) {        int x = rdm.nextInt(width);        int y = rdm.nextInt(height);        g.drawOval(x, y, 0, 0);    }    // generate a random code    String capstr = hash1.substring(0, 4);    //将验证码存入session    session.setAttribute("validateCode", capstr);    g.setColor(new Color(0, 100, 0));    g.setFont(new Font("Candara", Font.BOLD, 24));    g.drawString(capstr, 8, 24);    g.dispose();    response.setContentType("image/jpeg");    out.clear();    out = pageContext.pushBody();    OutputStream strm = response.getOutputStream();    ImageIO.write(image, "jpeg", strm);    strm.close();%>