利用struts生成随机验证码(JAVA)

       大部分WEB项目都会用到登录功能，而登录功能大部分又会涉及到动态验证码的生成！那如何通过后台生成动态验证码并传到后台呢？这就是我今天所要写的：
        标题：动态验证码的生成
      开发语言：JAVA
      SSH使用情况：只用到Struts2
      开发工具：MyEclipse
      运行环境：Tomcat
      示例代码包括内容：后台action、后台Util工具类、Struts配置、前台显示JSP、struts所用到的Jar包、Jquery.js
      
      a、Struts.xml配置如下：
         <?xml version="1.0" encoding="UTF-8"?>
         <!DOCTYPE struts PUBLIC 
  "-//Apache Software Foundation//DTD Struts Configuration 2.0//EN"
  "http://struts.apache.org/dtds/struts-2.0.dtd">
         <struts>
   <package name="testCaptcha" namespace="/test" extends="struts-default">
<action name="captcha" class="com.tf.action.CreateCaptchaAction" method="createCaptcha">
<result name="create" type="stream">
<param name="inputName">captchaInput</param>
<param name="contentType">image/jpeg</param>
</result>
</action>
<action name="createCaptcha" class="com.tf.action.CreateCaptchaAction" method="create">
<result name="success">
/WEB-INF/captcha/createCaptcha.jsp
</result>
</action>
   </package>
         </struts>
      b、后台action代码：
        package com.tf.action;


        import java.awt.image.BufferedImage;
        import java.io.ByteArrayInputStream;
        import java.io.ByteArrayOutputStream;
        import java.util.Map;
        import javax.imageio.ImageIO;
        import javax.imageio.stream.ImageOutputStream;
        import org.apache.struts2.interceptor.SessionAware;
        import com.opensymphony.xwork2.ActionSupport;
        import com.tf.util.CommentUtil;


        public class CreateCaptchaAction extends ActionSupport implements SessionAware{


private static final long serialVersionUID = -3429709930752736694L;


/**
* 验证码
*/
private ByteArrayInputStream captchaInput;
private String str;
private Map<String, Object> session;

/**
* 获取验证码
* @return
*/
public String createCaptcha() {
try {
setCaptchaInput(createInputStream());
} catch (Exception e) {
e.printStackTrace();
}
return "create";
}

public String create() {
return SUCCESS;
}

/**
* 将图片的以字节形式写到InputStream里
* 
* @return
* @throws Exception
*/
private ByteArrayInputStream createInputStream() throws Exception {
// 生成4位的随机串
String str = CommentUtil.generateRandCode(4);
BufferedImage image = CommentUtil.createImage(str);
session.put("validateCode", str);
ByteArrayOutputStream output = new ByteArrayOutputStream();
ImageOutputStream imageOut = ImageIO.createImageOutputStream(output);
ImageIO.write(image, "JPEG", imageOut);
imageOut.close();
ByteArrayInputStream input = new ByteArrayInputStream(output.toByteArray());
output.close();
return input;
}


get()、set()方法....

       }
     c、后台Util工具类
       package com.tf.util;


       import java.awt.Color;
       import java.awt.Font;
       import java.awt.Graphics;
       import java.awt.image.BufferedImage;
       import java.util.Random;


       public class CommentUtil {


/**
* 生成指定位数的随机码
* 
* @param codeLen (位数)
* @return
*/
public static String generateRandCode(int codeLen) {
int count = 0;
char str[] = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9','a','b','c','d','e','f','g',
'h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z','A','B',
'C','D','E','F','G','H','I','J','K','L','M','N','O','P','Q','R','S','T','U','V','W','X','Y','Z'};
StringBuffer pwd = new StringBuffer();
Random random = new Random();
while (count < codeLen) {
int i = Math.abs(random.nextInt(62));
if ((i >= 0) && (i < str.length)) {
pwd.append(str[i]);
count++;
}
}
return pwd.toString();
}

/**
* 生成一个内存图片，将四个随机数写在图片上
* 
* @param str 随机字符串
*/
public static BufferedImage createImage(String str) {
int width = 80;
int height = 25;


BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);


// 获取图形上下文
Graphics g = image.getGraphics();


// 设定验证码图片背景色
g.setColor(Color.WHITE);
g.fillRect(0, 0, width, height);


// 设定验证码图片边框颜色
g.setColor(Color.BLACK);
g.drawRect(0, 0, width - 1, height - 1);


// 添加干扰点
Random random = new Random();
for (int i = 0; i < 30; i++) {
g.drawOval(random.nextInt(width), random.nextInt(height), 0, 0);
}

// 添加干扰线
g.setColor(Color.YELLOW);
for (int i = 0; i < 10; i++) {
int x1 = random.nextInt(width);
int y1 = random.nextInt(height);
int x2 = random.nextInt(width + 80);
int y2 = random.nextInt(height + 25);
g.drawLine(x1, y1, x2, y2);
}

// 设置验证码字体
g.setFont(new Font("Atlantic Inline", Font.PLAIN, 20));


g.setColor(new Color(random.nextInt(256), random.nextInt(256), random.nextInt(256)));
g.drawString(Character.toString(str.charAt(0)), 5, 20);
g.setColor(new Color(random.nextInt(256), random.nextInt(256), random.nextInt(256)));
g.drawString(Character.toString(str.charAt(1)), 25, 20);
g.setColor(new Color(random.nextInt(256), random.nextInt(256), random.nextInt(256)));
g.drawString(Character.toString(str.charAt(2)), 45, 20);
g.setColor(new Color(random.nextInt(256), random.nextInt(256), random.nextInt(256)));
g.drawString(Character.toString(str.charAt(3)), 65, 20);


// 图象生效
g.dispose();
return image;
}


       }
     d、前台显示JSP：
       <%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
       <%
         String path = request.getContextPath();
         String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
       %>


       <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
   <html>
    <head>
    <base href="<%=basePath%>">
    
    <title>My JSP 'createCaptcha.jsp' starting page</title>
    
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">    
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">
<script type="text/javascript" src="<%=basePath%>js/jquery.js"></script>
<script type="text/javascript" src="<%=basePath%>js/jquery.pager.js"></script>
<script type="text/javascript">
$(function () {  
    //点击图片更换验证码
    $("#verify").click(function(){
        $(this).attr("src","test/captcha!createCaptcha?timestamp="+new Date().getTime());
    });
     });
</script>


  </head>
  
  <body>
  <form action="test/checkCaptcha!check">
  <table>
  <tr>
  <th>验证码:</th>
  <td><input style="width: 80; font-size: 16; letter-spacing: 5; text-align: center;" type="text" name="str"/></td>
  <td><img src="test/captcha!createCaptcha" id="verify" style="cursor:hand;" alt="看不清，换一张"/></td>
  </tr>
  <tr align="center">
  <td colspan="3"><input type="submit" value="开始验证"></td>
  </tr>
  </table>
  </form>
  </body>
  </html>
  e、WEB.XML配置：
     <filter>
  <filter-name>struts2</filter-name>
  <filter-class>
  org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter
  </filter-class>
     </filter>
     <filter-mapping>
  <filter-name>struts2</filter-name>
  <url-pattern>/*</url-pattern>
     </filter-mapping>
 
 中间所用的struts相关jar包，Jquery.js文件，网上多的是。当然JSP中用到的那段Jquery代码也可以用JS代码代替，根绝情况自己来写！