验证码生成类

package vcode;import java.awt.Color;import java.awt.Font;import java.awt.Graphics;import java.awt.image.BufferedImage;import java.util.Random;/** * 验证码,自成验证码，验证码包含一个字符串编码和对应的图片编码 *  * @author TaoPeng *  */public class VerificationCode {    private static final String character = "0123456789ABCDEFGHIGKLMNOPQRSTUVWXYZabcdefghigklmnopqrstuvwxyz";    /**     * 验证码的图片格式     */    private BufferedImage bufferImage;    /**     * 验证码的字符串格式     */    private String code;    public BufferedImage getImageData() {if (this.bufferImage == null) {    init();}return this.bufferImage;    }    public String getCode() {if (this.code == null) {    init();}return this.code;    }    /**     * 刷新验证码     */    public void refresh() {produce();    }    /**     * 初始化     */    private void init() {produce();    }    /**     * 生成新的验证码     */    private void produce() {int width = 100, height = 20;// 在内存中创建图象BufferedImage image = new BufferedImage(width, height,BufferedImage.TYPE_INT_RGB);// 获取图形上下文Graphics g = image.getGraphics();// 生成随机类Random random = new Random();// 设定背景色g.setColor(getRandColor(200, 250));g.fillRect(0, 0, width, height);// 设定字体g.setFont(new Font("Times New Roman", Font.PLAIN, 18));// 画边框// g.setColor(new Color());// g.drawRect(0,0,width-1,height-1);// 随机产生155条干扰线，使图象中的认证码不易被其它程序探测到g.setColor(getRandColor(160, 200));for (int i = 0; i < 500; i++) {    int x = random.nextInt(width);    int y = random.nextInt(height);    int xl = random.nextInt(12);    int yl = random.nextInt(12);    g.drawLine(x, y, x + xl, y + yl);}// 取随机产生的认证码(4位数字)char sRand;String rand = "";for (int i = 0; i < 6; i++) {    sRand = character.charAt(Math.abs(random.nextInt()) % 62);    rand = rand + sRand;    // 将认证码显示到图象中    g.setColor(new Color(20 + random.nextInt(110), 20 + random    .nextInt(110), 20 + random.nextInt(110)));// 调用函数出来的颜色相同，可能是因为种子太接近，所以只能直接生成    g.drawString(String.valueOf(sRand), 13 * i + 6, 16);}this.code = rand;this.bufferImage = image;    }    /**     * 给定范围获得随机颜色     *      * @param fc     * @param bc     * @return     */    private Color getRandColor(int fc, int bc) {Random random = new Random();if (fc > 255)    fc = 255;if (bc > 255)    bc = 255;int r = fc + random.nextInt(bc - fc);int g = fc + random.nextInt(bc - fc);int b = fc + random.nextInt(bc - fc);return new Color(r, g, b);    }}

获取验证码的servlet

package servlet;import java.awt.image.BufferedImage;import java.io.IOException;import javax.imageio.ImageIO;import javax.servlet.Servlet;import javax.servlet.ServletConfig;import javax.servlet.ServletException;import javax.servlet.ServletOutputStream;import javax.servlet.ServletRequest;import javax.servlet.ServletResponse;import javax.servlet.http.Cookie;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import javax.servlet.http.HttpSession;import vcode.VerificationCode;public class VerifySrv implements Servlet {    @Override    public void destroy() {    }    @Override    public ServletConfig getServletConfig() {return null;    }    @Override    public String getServletInfo() {return null;    }    @Override    public void init(ServletConfig arg0) throws ServletException {    }    @Override    public void service(ServletRequest arg0, ServletResponse arg1)    throws ServletException, IOException {HttpServletRequest request = (HttpServletRequest) arg0;HttpServletResponse response = (HttpServletResponse) arg1;response.setContentType("image/jpeg");response.setHeader("Pragma", "No-cache");response.setHeader("Cache-Control", "no-cache");response.setDateHeader("Expires", 0);// 获取验证码VerificationCode vCode = new VerificationCode();BufferedImage bufferImage = vCode.getImageData();// 保存验证码HttpSession session = request.getSession();response.addCookie(new Cookie("JSSESIONID", session.getId()));// 输出图象到页面ServletOutputStream responseOutputStream = response.getOutputStream();ImageIO.write(bufferImage, "JPEG", responseOutputStream);responseOutputStream.flush();responseOutputStream.close();    }}