使用开源项目patchca生成验证码

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配置web.xml

   <servlet>
    <description>This is the description of my J2EE component</description>
    <display-name>This is the display name of my J2EE component</display-name>
<servlet-name>VerifyCodeServlet</servlet-name>
<servlet-class>servlet.VerifyCodeServlet</servlet-class>
</servlet>

<servlet-mapping>
<servlet-name>VerifyCodeServlet</servlet-name>
<url-pattern>/patchca.png</url-pattern>
</servlet-mapping>

创建servlet

/**
* Copyright(C) 2012, 河北工业职业技术学院.
*
* 模块名称：   登录模块
* 子模块名称：   验证码模块
*
* 备注：
*
* 修改历史：
* 时间           版本号       姓名           修改内容
* 2012-6-7       V1.0       李玮           新建
*/
package servlet;

import java.io.IOException;
import java.io.PrintWriter;
import java.awt.Color;
import java.io.IOException;
import java.io.OutputStream;
import java.util.Random;

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.color.ColorFactory;
import org.patchca.color.SingleColorFactory;
import org.patchca.filter.predefined.CurvesRippleFilterFactory;
import org.patchca.filter.predefined.DiffuseRippleFilterFactory;
import org.patchca.filter.predefined.DoubleRippleFilterFactory;
import org.patchca.filter.predefined.MarbleRippleFilterFactory;
import org.patchca.filter.predefined.WobbleRippleFilterFactory;
import org.patchca.font.FontFactory;
import org.patchca.font.RandomFontFactory;
import org.patchca.service.ConfigurableCaptchaService;
import org.patchca.text.renderer.BestFitTextRenderer;
import org.patchca.text.renderer.RandomYBestFitTextRenderer;
import org.patchca.text.renderer.SimpleTextRenderer;
import org.patchca.text.renderer.TextRenderer;
import org.patchca.utils.encoder.EncoderHelper;
import org.patchca.word.RandomWordFactory;
/**
* 验证码生成类
*
* 本类的简要描述：
* 使用开源验证码项目patchca生成
* jar包：patchca-0.5.0.jar
* 项目网址：https://code.google.com/p/patchca/
* 项目中文介绍：http://baike.baidu.com/view/6925997.htm?fromTaglist
*
* @author
* @version 1.00 2012-6-7 新建类
*/

public class VerifyCodeServlet extends HttpServlet {
   private static final long serialVersionUID = 3796351198097771007L;
   private static ConfigurableCaptchaService ccs = null;
   private static ColorFactory cf = null;
   private static TextRenderer tr = null;
   private static RandomFontFactory ff = null;
   private static RandomWordFactory rwf = null;
   private static Random r = new Random();
   //private static CurvesRippleFilterFactory crff = null; //干扰线波纹
   //private static MarbleRippleFilterFactory mrff = null; //大理石波纹
   //private static DoubleRippleFilterFactory drff = null; //双波纹
   private static WobbleRippleFilterFactory wrff = null;   //摆波纹
   //private static DiffuseRippleFilterFactory dirff = null; //漫波纹

   /**
   * Constructor of the object.
   */
   public VerifyCodeServlet() {
       super();
   }

   /**
   * Initialization of the servlet. <br>
   *
   * @throws ServletException if an error occurs
   */
   public void init() throws ServletException {
       // Put your code here
       super.init();
       ccs = new ConfigurableCaptchaService();
       cf = new SingleColorFactory(new Color(25, 60, 170));
       ff = new RandomFontFactory();
       rwf = new RandomWordFactory();
       tr = new BestFitTextRenderer();
       //crff = new CurvesRippleFilterFactory(ccs.getColorFactory());
       //drff = new DoubleRippleFilterFactory();
       wrff = new WobbleRippleFilterFactory();
       //dirff = new DiffuseRippleFilterFactory();
       //mrff = new MarbleRippleFilterFactory();
       rwf.setCharacters("123456789");
       ff.setRandomStyle(false);
       ff.setMaxSize(16);
       ff.setMinSize(12);
       ccs.setTextRenderer(tr);
       ccs.setFontFactory(ff);
       ccs.setWordFactory(rwf);
       ccs.setColorFactory(cf);
       ccs.setWidth(50);
       ccs.setHeight(20);
   }

   /**
   * The doGet method of the servlet. <br>
   *
   * This method is called when a form has its tag value method equals to get.
   *
   * @param request the request send by the client to the server
   * @param response the response send by the server to the client
   * @throws ServletException if an error occurred
   * @throws IOException if an error occurred
   */
   public void doGet(HttpServletRequest request, HttpServletResponse response)
           throws ServletException, IOException {

       response.setContentType("image/png");
       response.setHeader("cache", "no-cache");
       rwf.setMaxLength(4);
       rwf.setMinLength(4);
       HttpSession session = request.getSession(true);
       OutputStream os = response.getOutputStream();
       ccs.setFilterFactory(wrff);
       /*switch (r.nextInt(5)) {
       case 0:
           ccs.setFilterFactory(drff);
           break;
       case 1:
           ccs.setFilterFactory(mrff);
           break;
       case 2:
           ccs.setFilterFactory(drff);
           break;
       case 3:
           ccs.setFilterFactory(wrff);
           break;
       case 4:
           ccs.setFilterFactory(dirff);
           break;
       }*/
       String captcha = EncoderHelper.getChallangeAndWriteImage(ccs, "png", os);
       session.setAttribute("captcha", captcha);
       os.flush();
       os.close();
   }

   /**
   * The doPost method of the servlet. <br>
   *
   * This method is called when a form has its tag value method equals to post.
   *
   * @param request the request send by the client to the server
   * @param response the response send by the server to the client
   * @throws ServletException if an error occurred
   * @throws IOException if an error occurred
   */
   public void doPost(HttpServletRequest request, HttpServletResponse response)
           throws ServletException, IOException {

       this.doGet(request, response);
   }

   /**
   * Destruction of the servlet. <br>
   */
   public void destroy() {
       rwf = null;
       cf = null;
       ccs = null;
       ff = null;
       super.destroy(); // Just puts "destroy" string in log
       // Put your code here
   }

}

jsp页面访问servlet

验证码:<input type="text" name="patchcafield"><br />

</form></td></tr></table>

jsp页面取出session中的验证码

<%//"PATCHCA"和servlet中定义的session保存位置对应

String c = (String)session.getAttribute("PATCHCA");

String parm = (String) request.getParameter("patchcafield");

out.println("Parameter: " + parm + " ? Session Key: " + c + " : ");

if (c != null && parm != null) {

if (c.equalsIgnoreCase(parm)) {

out.println("<b>true</b>");

} else {

out.println("<b>false</b>");

}}%>

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