package com.ninemax.cul.servlet;  
  
import java.awt.Color;  
import java.awt.Graphics;  
import java.awt.image.BufferedImage;  
import java.awt.image.BufferedImageOp;  
import java.io.IOException;  
import java.io.OutputStream;  
import java.util.ArrayList;  
import java.util.List;  
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;  
import javax.servlet.http.HttpSession;  
  
import org.patchca.background.BackgroundFactory;  
import org.patchca.color.ColorFactory;  
import org.patchca.color.RandomColorFactory;  
import org.patchca.filter.ConfigurableFilterFactory;  
import org.patchca.filter.library.AbstractImageOp;  
import org.patchca.filter.library.WobbleImageOp;  
import org.patchca.font.RandomFontFactory;  
import org.patchca.service.Captcha;  
import org.patchca.service.ConfigurableCaptchaService;  
import org.patchca.text.renderer.BestFitTextRenderer;  
import org.patchca.text.renderer.TextRenderer;  
import org.patchca.word.RandomWordFactory;  
  
/**  
 * 验证码生成类  
 *  
 * 使用开源验证码项目patchca生成  
 * 依赖jar包：patchca-0.5.0.jar  
 * 项目网址：https://code.google.com/p/patchca/  
 *  
 * @author zyh 
 * @version 1.00  2012-7-12 New  
 */  
public class ValidationCodeServlet extends HttpServlet {  
    private static final long serialVersionUID = 5126616339795936447L;  
      
    private ConfigurableCaptchaService configurableCaptchaService = null;  
    private ColorFactory colorFactory = null;  
    private RandomFontFactory fontFactory = null;  
    private RandomWordFactory wordFactory = null;  
    private TextRenderer textRenderer = null;  
      
    public ValidationCodeServlet() {  
        super();  
    }  
  
    /** 
     * Servlet销毁方法,负责销毁所使用资源. <br> 
     */  
    public void destroy() {  
        wordFactory = null;  
        colorFactory = null;  
        fontFactory = null;  
        textRenderer = null;  
        configurableCaptchaService = null;  
        super.destroy(); // Just puts "destroy" string in log  
    }  
  
    public void doGet(HttpServletRequest request, HttpServletResponse response)  
            throws ServletException, IOException {  
        doPost(request, response);  
    }  
  
    public void doPost(HttpServletRequest request, HttpServletResponse response)  
            throws ServletException, IOException {  
        response.setContentType("image/png");  
        response.setHeader("cache", "no-cache");  
          
        HttpSession session = request.getSession(true);  
        OutputStream outputStream = response.getOutputStream();  
          
        // 得到验证码对象,有验证码图片和验证码字符串  
        Captcha captcha = configurableCaptchaService.getCaptcha();  
        // 取得验证码字符串放入Session  
        String validationCode = captcha.getChallenge();  
        session.setAttribute("validationCode", validationCode);  
        // 取得验证码图片并输出  
        BufferedImage bufferedImage = captcha.getImage();  
        ImageIO.write(bufferedImage, "png", outputStream);  
          
        outputStream.flush();  
        outputStream.close();  
    }  
  
    /** 
     * Servlet初始化方法 
     */  
    public void init() throws ServletException {  
        configurableCaptchaService = new ConfigurableCaptchaService();  
          
        // 颜色创建工厂,使用一定范围内的随机色  
        colorFactory = new RandomColorFactory();  
        configurableCaptchaService.setColorFactory(colorFactory);  
          
        // 随机字体生成器  
        fontFactory = new RandomFontFactory();  
        fontFactory.setMaxSize(32);  
        fontFactory.setMinSize(28);  
        configurableCaptchaService.setFontFactory(fontFactory);  
          
        // 随机字符生成器,去除掉容易混淆的字母和数字,如o和0等  
        wordFactory = new RandomWordFactory();  
        wordFactory.setCharacters("abcdefghkmnpqstwxyz23456789");  
        wordFactory.setMaxLength(5);  
        wordFactory.setMinLength(4);  
        configurableCaptchaService.setWordFactory(wordFactory);  
          
        // 自定义验证码图片背景  
        MyCustomBackgroundFactory backgroundFactory = new MyCustomBackgroundFactory();  
        configurableCaptchaService.setBackgroundFactory(backgroundFactory);  
          
        // 图片滤镜设置  
        ConfigurableFilterFactory filterFactory = new ConfigurableFilterFactory();  
          
        List<BufferedImageOp> filters = new ArrayList<BufferedImageOp>();  
        WobbleImageOp wobbleImageOp = new WobbleImageOp();  
        wobbleImageOp.setEdgeMode(AbstractImageOp.EDGE_MIRROR);  
        wobbleImageOp.setxAmplitude(2.0);  
        wobbleImageOp.setyAmplitude(1.0);  
        filters.add(wobbleImageOp);  
        filterFactory.setFilters(filters);  
          
        configurableCaptchaService.setFilterFactory(filterFactory);  
          
        // 文字渲染器设置  
        textRenderer = new BestFitTextRenderer();  
        textRenderer.setBottomMargin(3);  
        textRenderer.setTopMargin(3);  
        configurableCaptchaService.setTextRenderer(textRenderer);  
          
        // 验证码图片的大小  
        configurableCaptchaService.setWidth(82);  
        configurableCaptchaService.setHeight(32);  
    }  
      
    /** 
     * 自定义验证码图片背景,主要画一些噪点和干扰线 
     */  
    private class MyCustomBackgroundFactory implements BackgroundFactory {  
        private Random random = new Random();  
  
        public void fillBackground(BufferedImage image) {  
            Graphics graphics = image.getGraphics();  
              
            // 验证码图片的宽高  
            int imgWidth = image.getWidth();  
            int imgHeight = image.getHeight();  
              
            // 填充为灰色背景  
            graphics.setColor(Color.GRAY);  
            graphics.fillRect(0, 0, imgWidth, imgHeight);  
              
            // 画100个噪点(颜色及位置随机)  
            for(int i = 0; i < 100; i++) {  
                // 随机颜色  
                int rInt = random.nextInt(255);  
                int gInt = random.nextInt(255);  
                int bInt = random.nextInt(255);  
                  
                graphics.setColor(new Color(rInt, gInt, bInt));  
                  
                // 随机位置  
                int xInt = random.nextInt(imgWidth - 3);  
                int yInt = random.nextInt(imgHeight - 2);  
                  
                // 随机旋转角度  
                int sAngleInt = random.nextInt(360);  
                int eAngleInt = random.nextInt(360);  
                  
                // 随机大小  
                int wInt = random.nextInt(6);  
                int hInt = random.nextInt(6);  
                  
                graphics.fillArc(xInt, yInt, wInt, hInt, sAngleInt, eAngleInt);  
                  
                // 画5条干扰线  
                if (i % 20 == 0) {  
                    int xInt2 = random.nextInt(imgWidth);  
                    int yInt2 = random.nextInt(imgHeight);  
                    graphics.drawLine(xInt, yInt, xInt2, yInt2);  
                }  
            }  
        }  
    }  
}  

<servlet>  
    <servlet-name>validationCode</servlet-name>  
    <servlet-class>com.ninemax.cul.servlet.ValidationCodeServlet</servlet-class>  
  </servlet>  
  
  <servlet-mapping>  
    <servlet-name>validationCode</servlet-name>  
    <url-pattern>/validationCodeServlet.png</url-pattern>  
  </servlet-mapping>  

<img id="validationCode" alt="验证码图片" title="验证码图片" src="<%=path %>/validationCodeServlet.png" onclick="refreshCode(this)" />  
<a id="aRecode" href="javascript:void(0);" onclick="refreshCode()">换一张</a>  

/** 
 * 刷新验证码 
 * @param imgObj 验证码Img元素 
 */  
function refreshCode(imgObj) {  
    if (!imgObj) {  
        imgObj = document.getElementById("validationCode");  
    }  
    var index = imgObj.src.indexOf("?");  
    if(index != -1) {  
        var url = imgObj.src.substring(0,index + 1);  
        imgObj.src = url + Math.random();  
    } else {  
        imgObj.src = imgObj.src + "?" + Math.random();  
    }  
}