JSP使用kaptcha.jar实现图片验证码

JSP使用kaptcha.jar实现图片验证码

1、下载kaptcha.jar包，导入到项目中。
地址：

http://download.csdn.net/download/qq_35227622/10020796

2、配置web.xml文件。

<servlet>        <servlet-name>Kaptcha</servlet-name>        <servlet-class>            com.google.code.kaptcha.servlet.KaptchaServlet        </servlet-class></servlet><servlet-mapping>    <servlet-name>Kaptcha</servlet-name>    <!--图片名-->    <url-pattern>/randomcode.jpg</url-pattern></servlet-mapping>

3、建立验证码页面，由于只是实现验证码，我并没有进行登录和注册。

<form method="get" action = "<%=request.getContextPath() %>/servlet/CodeServlet">    验证码：<input type = "text" name = "code" />    <img src ="randomcode.jpg" alt = "验证码" />    <a href ="javascript:void(0)">看不清</a>    <br />    <input type="submit" value="提交" /></form><script>    function changeCode() {        var that = document.getElementsByTagName("a")[0];        that.onclick = function() {            that.src = "randomcode.jpg?time="+new Date().getTime() ;        }    }</script>

4、创建Servlet，名为CodeServlet：

import java.io.IOException;import java.io.PrintWriter;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;public class CodeServlet extends HttpServlet {    public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {        request.setCharacterEncoding("utf-8");        response.setCharacterEncoding("utf-8");        //获得kaptcha包生成的验证码，它会存在session中，名为KAPTCHA_SESSION_KEY，可以在web.xml文件修改，后边介绍kaptcha的配置        String key = (String)session.getAttribute(com.google.code.kaptcha.Constants.KAPTCHA_SESSION_KEY);        //得到用户输入的验证码        String code = request.getParameter("code");        //进行判断是否相等        if(code.equals(key))            out.print("true");        else out.print("false");        out.print("<br>");        out.print(key + "====" + code);    }}

5、kaptcha实现图片验证码，对web.xml的配置使其更加丰富，可按照自己需要进行配置。

<servlet>        <servlet-name>Kaptcha</servlet-name>        <servlet-class>            com.google.code.kaptcha.servlet.KaptchaServlet        </servlet-class>        <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>black</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>1</param-value>        </init-param>        <init-param>            <description>图片宽 200</description>            <param-name>kaptcha.image.width</param-name>            <param-value>200</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>文本实现类</description>            <param-name>kaptcha.textproducer.impl</param-name>            <param-value>                com.google.code.kaptcha.text.impl.DefaultTextCreator            </param-value>        </init-param>        <init-param>            <description>文本集合，验证码值从此param-value集合中获取</description>            <param-name>kaptcha.textproducer.char.string</param-name>            <param-value>1234567890</param-value>        </init-param>        <init-param>            <description>验证码长度 5</description>            <param-name>kaptcha.textproducer.char.length</param-name>            <param-value>2</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>40</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>black</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.WaterRipple            </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>green</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，即验证码</description>            <param-name>kaptcha.session.key</param-name>            <param-value>KAPTCHA_SESSION_KEY</param-value>        </init-param>        <init-param>            <description>                kaptcha生成日期放入HttpSession。这是该项中的键值。            </description>            <param-name>kaptcha.session.date</param-name>            <param-value>KAPTCHA_SESSION_DATE</param-value>        </init-param>    </servlet>