Servlet实现数字字母验证码图片（一）：

生成验证码图片主要用到了一个BufferedImage类，如下：

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" alt="" />

1、引入jquery-1.10.2.js文件，创建verifyCode.jsp

 <%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>

 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">

 <html>

 <head>

 <title>Java验证码</title>

 </head>

 <body>

     <table width="100%" border="0" cellspacing="0" cellpadding="0">

         <tr>

             <td width="100"></td>

             <td width="100">验证码：</td>

             <td width="150"><input id="veryCode" name="veryCode" type="text"

                 class="yzm" value="" onmouseout="isRightCode()" /></td>

             <td width="135"><img id="imgObj" alt="" src="${pageContext.request.contextPath}/DrawImage"

                 onclick="changeImg()" /></td>

             <td><a href="javascript:void(0);" onclick="changeImg()">看不清，换一张</a></td>

             <td></td>

         </tr>

         <tr>

             <td style="line-height: 38px; color: #FF0000; text-align: center;"

                 colspan="4" id="info"></td>

             <td></td>

         </tr>

     </table>

 </body>

 <script type="text/javascript"    src="js/jquery-1.10.2.js"></script>

 <script type="text/javascript">

         /**

          * 验证code-js

          */

         // 点击换一张验证码

         function changeImg() {

             var imgSrc = $("#imgObj");

             var src = imgSrc.attr("src");

             //时间戳 ,为了使每次生成图片不一致，即不让浏览器读缓存，所以需要加上时间戳

             var timestamp = (new Date()).valueOf();

             src =src +"?timestamp=" + timestamp;;

             imgSrc.attr("src", src);

             $("#info").html("");

         }

         // 验证码验证

         function isRightCode() {

             var code = $("#veryCode").val();

             alert("code="+code);

             code = "c=" + code;

             $.ajax({

                 type : "POST",

                 url : "resultServlet",

                 data : code,

                 success :function callback(data) {// 验证以后处理提交信息或错误信息

                     if (data.toString() == 1) {

                         $("#info").html("提示您：验证成功了！");

                         return;

                     } else {

                         $("#info").html(data);

                         return;

                     }

                 }

             });

         }

 </script>

 </html>

2.创建画图servlet，DrawImage.java

 package com.utils;

 import java.awt.Color;

 import java.awt.Font;

 import java.awt.Graphics;

 import java.awt.Graphics2D;

 import java.awt.image.BufferedImage;

 import java.io.IOException;

 import java.util.Random;

 import javax.imageio.ImageIO;

 import javax.servlet.ServletException;

 import javax.servlet.annotation.WebServlet;

 import javax.servlet.http.HttpServlet;

 import javax.servlet.http.HttpServletRequest;

 import javax.servlet.http.HttpServletResponse;

 /**

  * 生成随机验证码图片

  *

  * @author huang

  *

  */

 @WebServlet("/DrawImage")

 public class DrawImage extends HttpServlet {

     private static final long serialVersionUID = 1L;

     public static final int WIDTH = 120;

     public static final int HEIGHT = 30;

     // 在报java.lang.NoClassDefFoundError: Could not initialize class

     // javax.imageio.ImageIO错的时候加上这个很管用。

     static {

         ImageIO.scanForPlugins();

     }

     public void doGet(HttpServletRequest request, HttpServletResponse response)

             throws ServletException, IOException {

         this.doPost(request, response);

     }

     public void doPost(HttpServletRequest request, HttpServletResponse response)

             throws ServletException, IOException {

         request.setCharacterEncoding("utf-8");

         response.setContentType("text/html;charset=utf-8");

         // 创建缓存

         BufferedImage bi = new BufferedImage(WIDTH, HEIGHT,

                 BufferedImage.TYPE_INT_RGB);

         // 获得画布

         Graphics g = bi.getGraphics();

         // 设置背影色

         setBackGround(g);

         // 设置边框

         setBorder(g);

         // 画干扰线

         drawRandomLine(g);

         // 写随机数

         String random = drawRandomNum((Graphics2D) g);

         // 将随机汉字存在session中

         request.getSession().setAttribute("checkcode", random);

         // 将图形写给浏览器

         response.setContentType("image/jpeg");

         // 发头控制浏览器不要缓存

         response.setDateHeader("expries", -1);

         response.setHeader("Cache-Control", "no-cache");

         response.setHeader("Pragma", "no-cache");

         // 将图片写给浏览器

         ImageIO.write(bi, "jpg", response.getOutputStream());

     }

     /**

      * 设置背景色

      *

      * @param g

      */

     private void setBackGround(Graphics g) {

         // 设置颜色

         g.setColor(new Color(249, 249, 249));

         // 填充区域

         g.fillRect(0, 0, WIDTH, HEIGHT);

     }

     /**

      * 设置边框

      *

      * @param g

      */

     private void setBorder(Graphics g) {

         // 设置边框颜色

         // RGB

         g.setColor(new Color(210, 209, 205));

         // 边框区域

         g.drawRect(1, 1, WIDTH - 2, HEIGHT - 2);

     }

     /**

      * 画随机线条

      *

      * @param g

      */

     private void drawRandomLine(Graphics g) {

         // 设置颜色

         g.setColor(Color.GRAY);

         // 设置线条个数并画线

         for (int i = 0; i <; i++) {

             int x1 = new Random().nextInt(WIDTH);

             int y1 = new Random().nextInt(HEIGHT);

             int x2 = new Random().nextInt(WIDTH);

             int y2 = new Random().nextInt(HEIGHT);

             g.drawLine(x1, y1, x2, y2);

         }

     }

     /**

      * 画随机汉字

      *

      * @param g

      * @return

      */

     private String drawRandomNum(Graphics2D g) {

         StringBuffer sb = new StringBuffer();

         // 设置字体

         g.setFont(new Font("宋体", Font.BOLD, 20));

         // 准备常用汉字集

         // String base =

         // "\u7684\u4e00\u4e86\u662f\u6211\u4e0d\u5728\u4eba\u4eec\u6709\u6765\u4ed6\u8fd9\u4e0a\u7740\u4e2a\u5730\u5230\u5927\u91cc\u8bf4\u5c31\u53bb\u5b50\u5f97\u4e5f\u548c\u90a3\u8981\u4e0b\u770b\u5929\u65f6\u8fc7\u51fa\u5c0f\u4e48\u8d77\u4f60\u90fd\u628a\u597d\u8fd8\u591a\u6ca1\u4e3a\u53c8\u53ef\u5bb6\u5b66\u53ea\u4ee5\u4e3b\u4f1a\u6837\u5e74\u60f3\u751f\u540c\u8001\u4e2d\u5341\u4ece\u81ea\u9762\u524d\u5934\u9053\u5b83\u540e\u7136\u8d70\u5f88\u50cf\u89c1\u4e24\u7528\u5979\u56fd\u52a8\u8fdb\u6210\u56de\u4ec0\u8fb9\u4f5c\u5bf9\u5f00\u800c\u5df1\u4e9b\u73b0\u5c71\u6c11\u5019\u7ecf\u53d1\u5de5\u5411\u4e8b\u547d\u7ed9\u957f\u6c34\u51e0\u4e49\u4e09\u58f0\u4e8e\u9ad8\u624b\u77e5\u7406\u773c\u5fd7\u70b9\u5fc3\u6218\u4e8c\u95ee\u4f46\u8eab\u65b9\u5b9e\u5403\u505a\u53eb\u5f53\u4f4f\u542c\u9769\u6253\u5462\u771f\u5168\u624d\u56db\u5df2\u6240\u654c\u4e4b\u6700\u5149\u4ea7\u60c5\u8def\u5206\u603b\u6761\u767d\u8bdd\u4e1c\u5e2d\u6b21\u4eb2\u5982\u88ab\u82b1\u53e3\u653e\u513f\u5e38\u6c14\u4e94\u7b2c\u4f7f\u5199\u519b\u5427\u6587\u8fd0\u518d\u679c\u600e\u5b9a\u8bb8\u5feb\u660e\u884c\u56e0\u522b\u98de\u5916\u6811\u7269\u6d3b\u90e8\u95e8\u65e0\u5f80\u8239\u671b\u65b0\u5e26\u961f\u5148\u529b\u5b8c\u5374\u7ad9\u4ee3\u5458\u673a\u66f4\u4e5d\u60a8\u6bcf\u98ce\u7ea7\u8ddf\u7b11\u554a\u5b69\u4e07\u5c11\u76f4\u610f\u591c\u6bd4\u9636\u8fde\u8f66\u91cd\u4fbf\u6597\u9a6c\u54ea\u5316\u592a\u6307\u53d8\u793e\u4f3c\u58eb\u8005\u5e72\u77f3\u6ee1\u65e5\u51b3\u767e\u539f\u62ff\u7fa4\u7a76\u5404\u516d\u672c\u601d\u89e3\u7acb\u6cb3\u6751\u516b\u96be\u65e9\u8bba\u5417\u6839\u5171\u8ba9\u76f8\u7814\u4eca\u5176\u4e66\u5750\u63a5\u5e94\u5173\u4fe1\u89c9\u6b65\u53cd\u5904\u8bb0\u5c06\u5343\u627e\u4e89\u9886\u6216\u5e08\u7ed3\u5757\u8dd1\u8c01\u8349\u8d8a\u5b57\u52a0\u811a\u7d27\u7231\u7b49\u4e60\u9635\u6015\u6708\u9752\u534a\u706b\u6cd5\u9898\u5efa\u8d76\u4f4d\u5531\u6d77\u4e03\u5973\u4efb\u4ef6\u611f\u51c6\u5f20\u56e2\u5c4b\u79bb\u8272\u8138\u7247\u79d1\u5012\u775b\u5229\u4e16\u521a\u4e14\u7531\u9001\u5207\u661f\u5bfc\u665a\u8868\u591f\u6574\u8ba4\u54cd\u96ea\u6d41\u672a\u573a\u8be5\u5e76\u5e95\u6df1\u523b\u5e73\u4f1f\u5fd9\u63d0\u786e\u8fd1\u4eae\u8f7b\u8bb2\u519c\u53e4\u9ed1\u544a\u754c\u62c9\u540d\u5440\u571f\u6e05\u9633\u7167\u529e\u53f2\u6539\u5386\u8f6c\u753b\u9020\u5634\u6b64\u6cbb\u5317\u5fc5\u670d\u96e8\u7a7f\u5185\u8bc6\u9a8c\u4f20\u4e1a\u83dc\u722c\u7761\u5174\u5f62\u91cf\u54b1\u89c2\u82e6\u4f53\u4f17\u901a\u51b2\u5408\u7834\u53cb\u5ea6\u672f\u996d\u516c\u65c1\u623f\u6781\u5357\u67aa\u8bfb\u6c99\u5c81\u7ebf\u91ce\u575a\u7a7a\u6536\u7b97\u81f3\u653f\u57ce\u52b3\u843d\u94b1\u7279\u56f4\u5f1f\u80dc\u6559\u70ed\u5c55\u5305\u6b4c\u7c7b\u6e10\u5f3a\u6570\u4e61\u547c\u6027\u97f3\u7b54\u54e5\u9645\u65e7\u795e\u5ea7\u7ae0\u5e2e\u5566\u53d7\u7cfb\u4ee4\u8df3\u975e\u4f55\u725b\u53d6\u5165\u5cb8\u6562\u6389\u5ffd\u79cd\u88c5\u9876\u6025\u6797\u505c\u606f\u53e5\u533a\u8863\u822c\u62a5\u53f6\u538b\u6162\u53d4\u80cc\u7ec6";

         // String base =

         // "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ\u7684\u4e00\u4e86\u662f\u6211\u4e0d\u5728\u4eba\u4eec\u6709\u6765\u4ed6\u8fd9\u4e0a\u7740\u4e2a\u5730\u5230\u5927\u91cc\u8bf4\u5c31\u53bb\u5b50\u5f97\u4e5f\u548c\u90a3\u8981\u4e0b\u770b\u5929\u65f6\u8fc7\u51fa\u5c0f\u4e48\u8d77\u4f60\u90fd\u628a\u597d\u8fd8\u591a\u6ca1\u4e3a\u53c8\u53ef\u5bb6\u5b66\u53ea\u4ee5\u4e3b\u4f1a\u6837\u5e74\u60f3\u751f\u540c\u8001\u4e2d\u5341\u4ece\u81ea\u9762\u524d\u5934\u9053\u5b83\u540e\u7136\u8d70\u5f88\u50cf\u89c1\u4e24\u7528\u5979\u56fd\u52a8\u8fdb\u6210\u56de\u4ec0\u8fb9\u4f5c\u5bf9\u5f00\u800c\u5df1\u4e9b\u73b0\u5c71\u6c11\u5019\u7ecf\u53d1\u5de5\u5411\u4e8b\u547d\u7ed9\u957f\u6c34\u51e0\u4e49\u4e09\u58f0\u4e8e\u9ad8\u624b\u77e5\u7406\u773c\u5fd7\u70b9\u5fc3\u6218\u4e8c\u95ee\u4f46\u8eab\u65b9\u5b9e\u5403\u505a\u53eb\u5f53\u4f4f\u542c\u9769\u6253\u5462\u771f\u5168\u624d\u56db\u5df2\u6240\u654c\u4e4b\u6700\u5149\u4ea7\u60c5\u8def\u5206\u603b\u6761\u767d\u8bdd\u4e1c\u5e2d\u6b21\u4eb2\u5982\u88ab\u82b1\u53e3\u653e\u513f\u5e38\u6c14\u4e94\u7b2c\u4f7f\u5199\u519b\u5427\u6587\u8fd0\u518d\u679c\u600e\u5b9a\u8bb8\u5feb\u660e\u884c\u56e0\u522b\u98de\u5916\u6811\u7269\u6d3b\u90e8\u95e8\u65e0\u5f80\u8239\u671b\u65b0\u5e26\u961f\u5148\u529b\u5b8c\u5374\u7ad9\u4ee3\u5458\u673a\u66f4\u4e5d\u60a8\u6bcf\u98ce\u7ea7\u8ddf\u7b11\u554a\u5b69\u4e07\u5c11\u76f4\u610f\u591c\u6bd4\u9636\u8fde\u8f66\u91cd\u4fbf\u6597\u9a6c\u54ea\u5316\u592a\u6307\u53d8\u793e\u4f3c\u58eb\u8005\u5e72\u77f3\u6ee1\u65e5\u51b3\u767e\u539f\u62ff\u7fa4\u7a76\u5404\u516d\u672c\u601d\u89e3\u7acb\u6cb3\u6751\u516b\u96be\u65e9\u8bba\u5417\u6839\u5171\u8ba9\u76f8\u7814\u4eca\u5176\u4e66\u5750\u63a5\u5e94\u5173\u4fe1\u89c9\u6b65\u53cd\u5904\u8bb0\u5c06\u5343\u627e\u4e89\u9886\u6216\u5e08\u7ed3\u5757\u8dd1\u8c01\u8349\u8d8a\u5b57\u52a0\u811a\u7d27\u7231\u7b49\u4e60\u9635\u6015\u6708\u9752\u534a\u706b\u6cd5\u9898\u5efa\u8d76\u4f4d\u5531\u6d77\u4e03\u5973\u4efb\u4ef6\u611f\u51c6\u5f20\u56e2\u5c4b\u79bb\u8272\u8138\u7247\u79d1\u5012\u775b\u5229\u4e16\u521a\u4e14\u7531\u9001\u5207\u661f\u5bfc\u665a\u8868\u591f\u6574\u8ba4\u54cd\u96ea\u6d41\u672a\u573a\u8be5\u5e76\u5e95\u6df1\u523b\u5e73\u4f1f\u5fd9\u63d0\u786e\u8fd1\u4eae\u8f7b\u8bb2\u519c\u53e4\u9ed1\u544a\u754c\u62c9\u540d\u5440\u571f\u6e05\u9633\u7167\u529e\u53f2\u6539\u5386\u8f6c\u753b\u9020\u5634\u6b64\u6cbb\u5317\u5fc5\u670d\u96e8\u7a7f\u5185\u8bc6\u9a8c\u4f20\u4e1a\u83dc\u722c\u7761\u5174\u5f62\u91cf\u54b1\u89c2\u82e6\u4f53\u4f17\u901a\u51b2\u5408\u7834\u53cb\u5ea6\u672f\u996d\u516c\u65c1\u623f\u6781\u5357\u67aa\u8bfb\u6c99\u5c81\u7ebf\u91ce\u575a\u7a7a\u6536\u7b97\u81f3\u653f\u57ce\u52b3\u843d\u94b1\u7279\u56f4\u5f1f\u80dc\u6559\u70ed\u5c55\u5305\u6b4c\u7c7b\u6e10\u5f3a\u6570\u4e61\u547c\u6027\u97f3\u7b54\u54e5\u9645\u65e7\u795e\u5ea7\u7ae0\u5e2e\u5566\u53d7\u7cfb\u4ee4\u8df3\u975e\u4f55\u725b\u53d6\u5165\u5cb8\u6562\u6389\u5ffd\u79cd\u88c5\u9876\u6025\u6797\u505c\u606f\u53e5\u533a\u8863\u822c\u62a5\u53f6\u538b\u6162\u53d4\u80cc\u7ec6";

         // 准备常用字符集

         String base = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";

         int x = 5;

         // 控制字数

         for (int i = 0; i < 4; i++) {

             // 生成0-255的随机数

             int R = new Random().nextInt(256);

             int G = new Random().nextInt(256);

             int B = new Random().nextInt(256);

             // 设置每个随机数的颜色

             g.setColor(new Color(R, G, B));

             // 设置字体旋转角度

             int degree = new Random().nextInt() % 30;

             // 截取汉字

             String ch = base.charAt(new Random().nextInt(base.length())) + "";

             sb.append(ch);

             // 正向角度

             g.rotate(degree * Math.PI / 180, x, 20);

             g.drawString(ch, x, 20);

             // 反向角度

             g.rotate(-degree * Math.PI / 180, x, 20);

             x += 30;

         }

         return sb.toString();

     }

 }

3.创建验证结果servlet，ResultServlet.java

 package com.utils;

 import java.io.IOException;

 import java.io.PrintWriter;  

 import javax.servlet.ServletException;

 import javax.servlet.annotation.WebServlet;

 import javax.servlet.http.HttpServlet;

 import javax.servlet.http.HttpServletRequest;

 import javax.servlet.http.HttpServletResponse;  

 /**

  * 结果验证Servlet

  * @author huang

  *

  */

 @WebServlet("/resultServlet")

 public class ResultServlet extends HttpServlet {  

     /**

      *

      */

     private static final long serialVersionUID = 1L;  

     public void doGet(HttpServletRequest request, HttpServletResponse response)

             throws ServletException, IOException {  

         doPost(request, response);

     }  

     /**

      * 后台验证输入

      */

     public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

         response.setContentType("text/html;charset=utf-8");

         String validateC = (String) request.getSession().getAttribute("checkcode");

         //从前台传来的用户输入的验证码

         String veryCode = request.getParameter("c");

         System.out.println("veryCode:"+veryCode);

         PrintWriter out = response.getWriter();

         if (veryCode == null || "".equals(veryCode)) {

             out.println("请输入验证码！");

         } else {

 //          if (validateC.equals(veryCode)) {

             // 忽略大小写处理：

             if (validateC.equalsIgnoreCase(veryCode)) {

                 out.println(1);

             } else {

                 out.println("验证码输入错误！");

             }

         }

         out.flush();

         out.close();

     }  

 }

4、结果

项目下载：下载工程

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