我的生成校验码技术--demo(采用java反射技术和dwr技术)
0.准备工作：首先需要导入dwr.jar包
1.web.xml
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id="WebApp_ID" version="2.5">
  <display-name>demo232</display-name>
  <servlet>
	<servlet-name>dwr-invoker</servlet-name>
	<servlet-class>org.directwebremoting.servlet.DwrServlet</servlet-class>
  </servlet>
  <servlet-mapping>
	<servlet-name>dwr-invoker</servlet-name>
 	<url-pattern>/dwr/*</url-pattern>
  </servlet-mapping>
  <welcome-file-list>
    <welcome-file>index.html</welcome-file>
    <welcome-file>index.htm</welcome-file>
    <welcome-file>index.jsp</welcome-file>
    <welcome-file>default.html</welcome-file>
    <welcome-file>default.htm</welcome-file>
    <welcome-file>default.jsp</welcome-file>
  </welcome-file-list>
</web-app>

2.dwr.xml
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE dwr PUBLIC "-//GetAhead Limited//DTD Direct Web Remoting 2.0//EN" 
	"http://www.getahead.ltd.uk/dwr/dwr20.dtd">
<dwr>
	<allow>
		<create creator="new" javascript="obvalidateCode">
			<param name="class" value="com.test.GenerateNumber" />
		</create>
	</allow>
</dwr>

3.Constants.java
package com.test;

public class Constants {
	public static String KEY_1 = "1";
	public static String KEY_2 = "2";
	public static String KEY_3 = "3";
	public static String KEY_4 = "4";
	public static String KEY_5 = "5";
	public static String KEY_6 = "6";
	public static String KEY_7 = "7";
	public static String KEY_8 = "8";
	public static String KEY_9 = "9";
	public static String KEY_10 = "A";
	public static String KEY_11 = "B";
	public static String KEY_12 = "C";
	public static String KEY_13 = "D";
	public static String KEY_14 = "E";
	public static String KEY_15 = "F";
	public static String KEY_16 = "G";
	public static String KEY_17 = "H";
	public static String KEY_18 = "I";
	public static String KEY_19 = "J";
	public static String KEY_20 = "K";
	public static String KEY_21 = "L";
	public static String KEY_22 = "M";
	public static String KEY_23 = "N";
	public static String KEY_24 = "O";
	public static String KEY_25 = "P";
	public static String KEY_26 = "Q";
	public static String KEY_27 = "R";
	public static String KEY_28 = "S";
	public static String KEY_29 = "T";
	public static String KEY_30 = "U";
	public static String KEY_31 = "V";
	public static String KEY_32 = "W";
	public static String KEY_33 = "X";
	public static String KEY_34 = "Y";
	public static String KEY_35 = "Z";
	
	public static String COLOR_1 = "orange";
	public static String COLOR_2 = "pink";
	public static String COLOR_3 = "red";
	public static String COLOR_4 = "gray";
	public static String COLOR_5 = "blue";
	public static String COLOR_6 = "yellow";
	
	
}


4.GenerateNumber.java
package com.test;

import java.lang.reflect.Field;
import java.util.ArrayList;
import java.util.List;

public class GenerateNumber {
	public List<String> generate(){
		List<String> validateCodeList = new ArrayList<String>();
		/**生成随机码*/
		//产生1-35之间随机数：
		for(int i = 0; i < 4; i++){
			int x=1+(int)(Math.random()*35);
			String key = "KEY_"+x;
			System.out.print(x+"\t");
			try {
				Field field = Constants.class.getField(key);
				Object str = "C";
				try {
					str = field.get((Object)field.getName());
				} catch (IllegalArgumentException e) {
					e.printStackTrace();
				} catch (IllegalAccessException e) {
					e.printStackTrace();
				}
				validateCodeList.add(str.toString());
//				System.out.println(field.getName()+"\t"+str.toString());
			} catch (SecurityException e) {
				e.printStackTrace();
			} catch (NoSuchFieldException e) {
				e.printStackTrace();
			}
		}
		System.out.println();
		for(String s : validateCodeList){
			System.out.print(s+"\t");
		}
		System.out.println("\n------------------------");
		
		/**下面生成随机颜色*/
		int y=1+(int)(Math.random()*6);
		try {
			Field field = Constants.class.getField("COLOR_"+y);
			try {
				Object co = (Object)field.get("COLOR_"+y);
				validateCodeList.add(co.toString());
				System.out.println(co.toString());
			} catch (IllegalArgumentException e) {
				e.printStackTrace();
			} catch (IllegalAccessException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		} catch (SecurityException e) {
			e.printStackTrace();
		} catch (NoSuchFieldException e) {
			e.printStackTrace();
		}
		
		return validateCodeList;
	}
	public static void main(String[] args) {
		new GenerateNumber().generate();
	}
}

5.showTest.jsp
<%@ page language="java" contentType="text/html; charset=utf-8"
    pageEncoding="utf-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>dwr级联显示</title>
<!-- 使用的是相对路径，下面这个引用dwr/interface也是固定写法 -->
<script type='text/javascript' src='dwr/interface/obvalidateCode.js'></script>
<!-- 下面这两个引用是固定写法，因为这两个文件是在dwr.jar中 -->
<script type='text/javascript' src='dwr/engine.js'></script>
<script type='text/javascript' src='dwr/util.js'></script>
<script type="text/javascript">
	function hptest(){
		obvalidateCode.generate(show);
	}
	obvalidateCode.generate(show);
	function show(data){
		var st = data.toString();
		var s = st.split(",");
		//alert(s);
		for(var i = 0; i < s.length-1; i++){
			DWRUtil.setValue("stext_"+i,s[i]);
		}
		if(s.length > 4){
			document.getElementById("bgspan").style.backgroundColor=s[4];
		} 
	}
	function checkValidateCode(){
		var v1 = DWRUtil.getValue("stext_0");
		var v2 = DWRUtil.getValue("stext_1");
		var v3 = DWRUtil.getValue("stext_2");
		var v4 = DWRUtil.getValue("stext_3");
		var v_total = v1+v2+v3+v4;
		//alert(v1+","+v2+","+v3+","+v4);
		var colValue = document.getElementById("colValue").value;
		if(colValue != ""){
			if(v_total == colValue){
				alert(v_total+"______"+colValue);
				alert("校验码输入正确");
			}else{
				alert(v_total+"______"+colValue);
				alert("校验码输入错误");
			}
		}
	}
	
	
</script>
</head>
<body>
	<form id="myform">
		<b>验证码 :</b><input type="text" id="colValue" />
		<div id="bgspan" style="width:4%;"><I><b>
			<span id="stext_0"></span>
			<span id="stext_1"></span>
			<span id="stext_2"></span>
			<span id="stext_3"></span></b></I>
		</div>
		<br />
		<input type="button" value="validate" onclick="checkValidateCode()" />
	</form>
	
</body>
</html>