JavaWeb---制作验证码

来源：互联网发布：windows命令行设置ip 编辑：程序博客网时间：2024/05/21 17:45

说起验证码，绝壁是个让人蛋疼的问题，特别是节假日在12306上面抢票的时候遇到的外星系验证码，大大降低了用户的体验度！
可是作为我辈中人，还是要知道验证码为毛存在，其作用是什么！
如果再想深究，那么坐下来，让我们好好探讨探讨如何制作验证码！请跟我来……

验证码形式

字母数字组合、加减法、中英文、算式加减法……

为什么需要验证码

验证码降低了用户体验度，但是为什么存在呢？？？

如果没有验证码：

1) 对特定用户不断登录破解密码

2) 对某个网站创建账户

3) 对某个网站提交垃圾数据

4) 都某个网站刷票

如果存在验证码：

只有人亲自识别验证码，输入验证码内容，才能登录、发评论等等，防止计算机破解自动登录发灌水帖等；通过验证码来区分人和计算机；

制作验证码

验证码包含两部分：输入框和显示验证码的图片；

一般验证机制如下图：

可是，显示验证码的图片是如何产生的呢?

通过Servlet手工制作验证码（简单型）

1) 手工生成的验证码比较简单，用到的类有

2) BufferedImage图像数据缓冲区

3) Graphics绘制图片

4) Color获取颜色

5) Random生成随机数

6) ImageIO输出图片

ImageServlet类：

package hdu.terence; import java.awt.Color;import java.awt.Graphics;import java.awt.image.BufferedImage;import java.io.IOException;import java.io.PrintWriter;import java.util.Random; import javax.imageio.ImageIO;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;importjavax.servlet.http.HttpServletRequest;importjavax.servlet.http.HttpServletResponse; public class ImageServlet extendsHttpServlet {        publicImageServlet() {              super();       }        publicvoid destroy() {              super.destroy();       }       publicvoid doGet(HttpServletRequest request, HttpServletResponse response)                     throwsServletException, IOException {              BufferedImagebi=new BufferedImage(68,22,BufferedImage.TYPE_INT_RGB);              Graphicsg=bi.getGraphics();              Colorc=new Color(200,150,255);              g.setColor(c);              g.fillRect(0,0, 68, 22);              char[]ch="WQERTYUIOPASDFG127890HJKLZ3456XCVBNMmnbvcxzkjhgfdsaqwertyuiop".toCharArray();              Randomr=new Random();              intlen=ch.length,index;                           StringBuffersb=new StringBuffer();//用于保存图片              for(inti=0;i<4;i++)              {                     index=r.nextInt(len);                     g.setColor(newColor(r.nextInt(88),r.nextInt(188),r.nextInt(255)));                     g.drawString(ch[index]+"",(i*15)+3, 18);                     sb.append(ch[index]);              }              request.getSession().setAttribute("verifyCode",sb.toString());              ImageIO.write(bi,"JPG", response.getOutputStream());       }       publicvoid doPost(HttpServletRequest request, HttpServletResponse response)                     throwsServletException, IOException {       }       publicvoid init() throws ServletException {                    }}

LoginServlet类：

package hdu.terence; import java.io.IOException;import java.io.PrintWriter; import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;importjavax.servlet.http.HttpServletRequest;importjavax.servlet.http.HttpServletResponse; public class LoginServlet extendsHttpServlet {              publicLoginServlet() {              super();       }       publicvoid destroy() {       }       publicvoid doGet(HttpServletRequest request, HttpServletResponse response)                     throwsServletException, IOException {              response.setContentType("text/html;charset=gbk");              StringverifyCode=(String) request.getSession().getAttribute("verifyCode");              StringcheckCode=request.getParameter("checkCode");              verifyCode=verifyCode.toUpperCase();              checkCode=checkCode.toUpperCase();                           PrintWriterout=response.getWriter();              if(checkCode.equals(verifyCode))              {                     out.println("niece!验证码输入正确！");              }              else              {                     out.println("你似不似撒？验证码都能输入错误！！！！！！");              }              out.flush();              out.close();       }       publicvoid doPost(HttpServletRequest request, HttpServletResponse response)                     throwsServletException, IOException {       }       publicvoid init() throws ServletException {       }}

JSP：

<head> <script type="text/javascript">   function reloadVerifyCode()    {      var time =new Date().getTime();      document.getElementById("imageCode")      document.getElementById("imageCode").src="<%=request.getContextPath()%>/servlet/ImageServlet?d="+time;      //加time传递参数是为了区分请求连接，重新获取验证码；    }   </script>  </head>  <body>  <form action="<%=request.getContextPath() %>/servlet/LoginServlet" method="get">      验证码：<input type="text" name="checkCode"id="checkCode">      <img alt="验证码" id="imageCode"src="<%=request.getContextPath() %>/servlet/ImageServlet"/>      <a href="javascript:reloadVerifyCode();">看不清，重新获取</a><br>         <input type="submit"name="submit" value="确定">       <input type="reset"name="submit" value="重置">          </form>  </body>

结果：

通过Kaptcha开源组件制作验证码（花式验证码）

Kaptcha：这个工具是可配置的，可以生成各种花式的验证码，可通过配置参数增加机器识别难度。

准备步骤：

1) 下载kaptcha-2.3.jar（点击下载kaptcha-2.3.jar）

2) 将jar包导入项目，添加到路径

3) 编写页面

4) 配置web.xml

5) 启动项目

数字、英文混合验证

Step1 JSP：

<table>      <tr>        <th>输入验证码：</th>        <th align="left" > <input name="checkCode"Id="checkCode" type="text"/></th>      </tr>      <tr>        <th> </th>        <th><img  src="randomcode.jpg">看不清，重换一张 </th>      </tr>      <tr>          <th> </th>        <th align="left">        <input type="submit" value="确定"/>           <input type="reset" value="重置"/>        </th>      </tr>      </table>

src：连接到后台生成的randomcode.jpg；

Step2 在web.xml中添加映射配置：

<servlet-mapping>  <servlet-name>kaptcha</servlet-name>  <url-pattern>/randomcode.jpg</url-pattern></servlet-mapping>

Step3 增加配置参数，防止机器识别图片；

可配置的参数如下：

<span style="color:#000000;"><init-param>  <description>图片边框，合法值：yes , no</description>  <param-name>kaptcha.border</param-name>  <param-value>yes</param-value>  </init-param>-<init-param>  <description>边框颜色，合法值： r,g,b (and optional alpha) 或者white,black,blue.</description>  <param-name>kaptcha.border.color</param-name>  <param-value>red</param-value>  </init-param>-<init-param>  <description>边框厚度，合法值：>0</description>  <param-name>kaptcha.border.thickness</param-name>  <param-value>2</param-value>  </init-param>-<init-param>  <description>图片宽 200</description>  <param-name>kaptcha.image.width</param-name>  <param-value>150</param-value>  </init-param>-<init-param>  <description>图片高 50</description>  <param-name>kaptcha.image.height</param-name>  <param-value>50</param-value>  </init-param>-<init-param>  <description>图片实现类</description>  <param-name>kaptcha.producer.impl</param-name>  <param-value>com.google.code.kaptcha.impl.DefaultKaptcha</param-value>  </init-param>-<init-param>  <description>不用文本实现：com.google.code.kaptcha.impl.DifaultTextCreator用文本实现：则用自己重写的中文类（内含算法）ChineseTextCheck.ChineseTextCode</description>  <param-name>kaptcha.textproducer.impl</param-name>  <param-value>ChineseTextCheck.ChineseTextCode</param-value>  </init-param>-<init-param>  <description>文本集合，验证码值从此集合中获取</description>  <param-name>kaptcha.textproducer.char.string</param-name>  <param-value>qwertys1zcmd2345s67g890</param-value>- <!--<param-value>abcde2345678gfynmnpwx</param-value>  -->- <!--<param-value>你好我好大家好</param-value>  -->  </init-param>-<init-param>  <description>验证码长度 5</description>  <param-name>kaptcha.textproducer.char.length</param-name>  <param-value>5</param-value>  </init-param>-<init-param>  <description>字体Arial, Courier</description>  <param-name>kaptcha.textproducer.font.names</param-name>  <param-value>Arial, Courier</param-value>  </init-param>-<init-param>  <description>字体大小 40px.</description>  <param-name>kaptcha.textproducer.font.size</param-name>  <param-value>30</param-value>  </init-param>-<init-param>  <description>字体颜色，合法值： r,g,b 或者 white,black,blue.</description>  <param-name>kaptcha.textproducer.font.color</param-name>  <param-value>black</param-value>  </init-param>-<init-param>  <description>文字间隔 2</description>  <param-name>kaptcha.textproducer.char.space</param-name>  <param-value>2</param-value>  </init-param>-<init-param>  <description>干扰实现类</description>  <param-name>kaptcha.noise.impl</param-name>-<param-value>- <!-- com.google.code.kaptcha.impl.NoNoise  -->  com.google.code.kaptcha.impl.DefaultNoise  </param-value>  </init-param>-<init-param>  <description>干扰颜色，合法值： r,g,b 或者 white,black,blue.</description>  <param-name>kaptcha.noise.color</param-name>  <param-value>blue</param-value>  </init-param>-<init-param>  <description>图片样式： 水纹com.google.code.kaptcha.impl.WaterRipple鱼眼com.google.code.kaptcha.impl.FishEyeGimpy阴影com.google.code.kaptcha.impl.ShadowGimpy</description>  <param-name>kaptcha.obscurificator.impl</param-name>  <param-value>com.google.code.kaptcha.impl.FishEyeGimpy</param-value>  </init-param>-<init-param>  <description>背景实现类</description>  <param-name>kaptcha.background.impl</param-name>  <param-value>com.google.code.kaptcha.impl.DefaultBackground</param-value>  </init-param>-<init-param>  <description>背景颜色渐变，开始颜色</description>  <param-name>kaptcha.background.clear.from</param-name>  <param-value>red</param-value>  </init-param>-<init-param>  <description>背景颜色渐变，结束颜色</description>  <param-name>kaptcha.background.clear.to</param-name>  <param-value>white</param-value>  </init-param>-<init-param>  <description>文字渲染器</description>  <param-name>kaptcha.word.impl</param-name>  <param-value>com.google.code.kaptcha.text.impl.DefaultWordRenderer</param-value>  </init-param>-<init-param>  <description>session中存放验证码的key键</description>  <param-name>kaptcha.session.key</param-name>  <param-value>KAPTCHA_SESSION_KEY</param-value>  </init-param>-<init-param>  <description>The date the kaptcha is generatedis put into the HttpSession. This is the key value for that item in thesession.</description>  <param-name>kaptcha.session.date</param-name>  <param-value>KAPTCHA_SESSION_DATE</param-value>  </init-param></span>

Step 4 结果

中文验证码

Step1 重写配置文件里面的TextProducer类

import java.util.Random;import com.google.code.kaptcha.text.TextProducer;importcom.google.code.kaptcha.util.Configurable; public class ChineseTextCode extendsConfigurable implements TextProducer {        /*        * 中文验证码(non-Javadoc)        * 粘贴以下算法重写文本实现类        * @see com.google.code.kaptcha.text.TextProducer#getText()        */       publicString getText() {              intlength = getConfig().getTextProducerCharLength();              StringfinalWord = "", firstWord = "";              inttempInt = 0;              String[]array = { "0", "1", "2", "3","4", "5", "6", "7", "8","9",                            "a","b", "c", "d", "e", "f" };               Randomrand = new Random();               for(int i = 0; i < length; i++) {                     switch(rand.nextInt(array.length)) {                     case1:                            tempInt= rand.nextInt(26) + 65;                            firstWord= String.valueOf((char) tempInt);                            break;                     case2:                            intr1,                            r2,                            r3,                            r4;                            StringstrH,                            strL;//high&low                            r1= rand.nextInt(3) + 11; // 前闭后开[11,14)                            if(r1 == 13) {                                   r2= rand.nextInt(7);                            }else {                                   r2= rand.nextInt(16);                            }                             r3= rand.nextInt(6) + 10;                            if(r3 == 10) {                                   r4= rand.nextInt(15) + 1;                            }else if (r3 == 15) {                                   r4= rand.nextInt(15);                            }else {                                   r4= rand.nextInt(16);                            }                             strH= array[r1] + array[r2];                            strL= array[r3] + array[r4];                             byte[]bytes = new byte[2];                            bytes[0]= (byte) (Integer.parseInt(strH, 16));                            bytes[1]= (byte) (Integer.parseInt(strL, 16));                             firstWord= new String(bytes);                            break;                     default:                            tempInt= rand.nextInt(10) + 48;                            firstWord= String.valueOf((char) tempInt);                            break;                     }                     finalWord+= firstWord;              }              returnfinalWord;       }        publicString getText1() {              intlength = getConfig().getTextProducerCharLength();              //char[]charS = getConfig().getTextProducerCharString();                           String[]s = new String[]{"我","是","阿","S","靖","卡","哥","滚","蛋","呸"};               Randomrand = new Random();              StringBuffersb = new StringBuffer();              for(inti = 0; i < length; i++){                     intind =rand.nextInt(s.length);                     sb.append(s[ind]);              }              returnsb.toString();       }}

Step2 然后修改配置文件web.xml

<init-param>        <description>文本实现类</description>        <param-name>kaptcha.textproducer.impl</param-name>        <param-value>           ChineseTextCheck.ChineseTextCode        </param-value></init-param>

Step 3 结果

算式验证码

以重写Servlet的方式实现算式验证码

步骤：

1) 获取随机数值，结果相加

2) 将计算公式写到图片上

3) 将相加结果保存到session中

4) 依此为目标重写KapthaServlet类

Step1 重写KaptchaServlet

package formula; import com.google.code.kaptcha.Producer;import com.google.code.kaptcha.util.Config;import java.awt.image.BufferedImage;import java.io.IOException;import java.util.Enumeration;import java.util.Properties;import javax.imageio.ImageIO;import javax.servlet.Servlet;import javax.servlet.ServletConfig;import javax.servlet.ServletException;import javax.servlet.ServletOutputStream;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;importjavax.servlet.http.HttpServletResponse;import javax.servlet.http.HttpSession; public class KaptchaServlet extendsHttpServlet implements Servlet {       privateProperties props;       privateProducer kaptchaProducer;       privateString sessionKeyValue;        publicKaptchaServlet() {              this.props= new Properties();               this.kaptchaProducer= null;               this.sessionKeyValue= null;       }        publicvoid init(ServletConfig conf) throws ServletException {              super.init(conf);               ImageIO.setUseCache(false);               EnumerationinitParams = conf.getInitParameterNames();              while(initParams.hasMoreElements()) {                     Stringkey = (String) initParams.nextElement();                     Stringvalue = conf.getInitParameter(key);                     this.props.put(key,value);              }               Configconfig = new Config(this.props);              this.kaptchaProducer= config.getProducerImpl();              this.sessionKeyValue= config.getSessionKey();       }        publicvoid doGet(HttpServletRequest req, HttpServletResponse resp)                     throwsServletException, IOException {              resp.setDateHeader("Expires",0L);               resp.setHeader("Cache-Control","no-store, no-cache, must-revalidate");               resp.addHeader("Cache-Control","post-check=0, pre-check=0");               resp.setHeader("Pragma","no-cache");               resp.setContentType("image/jpeg");               StringcapText = this.kaptchaProducer.createText();              Strings1 = capText.substring(0, 1);              Strings2 = capText.substring(1, 2);              intr = Integer.valueOf(s1).intValue() + Integer.valueOf(s2).intValue();               req.getSession().setAttribute(this.sessionKeyValue,String.valueOf(r));               BufferedImagebi = this.kaptchaProducer.createImage(s1+"+"+s2+"=?");               ServletOutputStreamout = resp.getOutputStream();               ImageIO.write(bi,"jpg", out);              try{                     out.flush();              }finally {                     out.close();              }       }}

Step2 配置web.xml

<servlet-name>kaptcha</servlet-name>       <description>文字、数字英文方式：com.google.code.kaptcha.servlet.KaptchaServlet                 算式：使用自己重写的类：formula.KaptchaServlet       </description><servlet-class>formula.KaptchaServlet</servlet-class>

上述中formula.KaptchaServlet是指自己在formula包下重写的KaptchaServlet类。

Step3 结果

References Demo

参考源码：verifyCode

0 2