struts2 验证码----web界面生成几种常见的验证码

   验证码是很多系统都需要的，下面是我写的几个常见的验证码的生成

主要生成几种不同类型的验证码
* 第一种：简单验证码，4位随机数字 ：

* 第二种：英文字符加数字的验证码 ：

* 第三种：像铁路订票系统一样的验证码，肆+？=21


下面是实现的验证码类，由于我这里是用的SSH2

package com.base.util;

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.util.Random;
import javax.imageio.ImageIO;
import javax.imageio.stream.ImageOutputStream;

/**
 * 验证码类，主要生成几种不同类型的验证码 
 * 第一种：简单验证码，4位随机数字 
 * 第二种：英文字符加数字的验证码 
 * 第三种：像铁路订票系统一样的验证码，肆+？=21
 * 
 * @author 李朋飞
 * 
 */
public class VerificationCodeUtil {
	private ByteArrayInputStream image;// 图像
	private String str;// 验证码
	private static final int WIDTH = 80;
	private static final int HEIGHT = 20;

	public static void main(String[] arg) {
		VerificationCodeUtil vcu = VerificationCodeUtil.Instance();
		System.err.println(vcu.getVerificationCodeValue());
	}

	/**
	 * 功能：获取一个验证码类的实例
	 * 
	 * @return
	 */
	public static VerificationCodeUtil Instance() {
		return new VerificationCodeUtil();
	}

	private VerificationCodeUtil() {
		BufferedImage image = new BufferedImage(WIDTH, HEIGHT,
				BufferedImage.TYPE_INT_RGB);
		int randomNum = new Random().nextInt(3);
		if (randomNum == 0) {
			initNumVerificationCode(image);
		} else if (randomNum == 1) {
			initLetterAndNumVerificationCode(image);
		} else {
			initChinesePlusNumVerificationCode(image);
		}
	}

	/**
	 * 功能：设置第一种验证码的属性
	 */
	public void initNumVerificationCode(BufferedImage image) {

		Random random = new Random(); // 生成随机类
		Graphics g = initImage(image, random);
		String sRand = "";
		for (int i = 0; i < 4; i++) {
			String rand = String.valueOf(random.nextInt(10));
			sRand += rand;
			// 将认证码显示到图象中
			g.setColor(new Color(20 + random.nextInt(110), 20 + random
					.nextInt(110), 20 + random.nextInt(110)));
			// 调用函数出来的颜色相同，可能是因为种子太接近，所以只能直接生成
			g.drawString(rand, 13 * i + 6, 16);
		}
		this.setStr(sRand);/* 赋值验证码 */
		// 图象生效
		g.dispose();
		this.setImage(drawImage(image));
	}

	/**
	 * 功能：设置第二种验证码属性
	 */
	public void initLetterAndNumVerificationCode(BufferedImage image) {

		Random random = new Random(); // 生成随机类
		Graphics g = initImage(image, random);
		String[] letter = { "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" };
		String sRand = "";
		for (int i = 0; i < 4; i++) {
			String tempRand = "";
			if (random.nextBoolean()) {
				tempRand = String.valueOf(random.nextInt(10));
			} else {
				tempRand = letter[random.nextInt(25)];
				if (random.nextBoolean()) {// 随机将该字母变成小写
					tempRand = tempRand.toLowerCase();
				}
			}
			sRand += tempRand;
			g.setColor(new Color(20 + random.nextInt(10), 20 + random
					.nextInt(110), 20 + random.nextInt(110)));
			g.drawString(tempRand, 13 * i + 6, 16);
		}
		this.setStr(sRand);/* 赋值验证码 */
		g.dispose(); // 图象生效
		this.setImage(drawImage(image));
	}

	/**
	 * 功能：设置第三种验证码属性 即：肆+？=24
	 */
	public void initChinesePlusNumVerificationCode(BufferedImage image) {
		String[] cn = { "壹", "贰", "叁", "肆", "伍", "陆", "柒", "捌", "玖", "拾" };
		Random random = new Random(); // 生成随机类
		Graphics g = initImage(image, random);
		int x = random.nextInt(10) + 1;
		int y = random.nextInt(30);
		this.setStr(String.valueOf(y));
		g.setFont(new Font("楷体", Font.PLAIN, 14));// 设定字体
		g.setColor(new Color(20 + random.nextInt(10), 20 + random.nextInt(110),
				20 + random.nextInt(110)));
		g.drawString(cn[x - 1], 1 * 1 + 6, 16);
		g.drawString("+", 22, 16);
		g.drawString("？", 35, 16);
		g.drawString("=", 48, 16);
		g.drawString(String.valueOf(x + y), 61, 16);
		g.dispose(); // 图象生效
		this.setImage(drawImage(image));

	}

	public Graphics initImage(BufferedImage image, Random random) {
		Graphics g = image.getGraphics(); // 获取图形上下文
		g.setColor(getRandColor(200, 250));// 设定背景色
		g.fillRect(0, 0, WIDTH, HEIGHT);
		g.setFont(new Font("Times New Roman", Font.PLAIN, 14));// 设定字体
		g.setColor(getRandColor(160, 200)); // 随机产生165条干扰线，使图象中的认证码不易被其它程序探测到
		for (int i = 0; i < 165; i++) {
			int x = random.nextInt(WIDTH);
			int y = random.nextInt(HEIGHT);
			int xl = random.nextInt(12);
			int yl = random.nextInt(12);
			g.drawLine(x, y, x + xl, y + yl);
		}
		return g;
	}

	public ByteArrayInputStream drawImage(BufferedImage image) {
		ByteArrayInputStream input = null;
		ByteArrayOutputStream output = new ByteArrayOutputStream();
		try {
			ImageOutputStream imageOut = ImageIO
					.createImageOutputStream(output);
			ImageIO.write(image, "JPEG", imageOut);
			imageOut.close();
			input = new ByteArrayInputStream(output.toByteArray());
		} catch (Exception e) {
			System.out.println("验证码图片产生出现错误：" + e.toString());
		}
		return input;
	}

	/*
	 * 功能：给定范围获得随机颜色
	 */
	private Color getRandColor(int fc, int bc) {
		Random random = new Random();
		if (fc > 255)
			fc = 255;
		if (bc > 255)
			bc = 255;
		int r = fc + random.nextInt(bc - fc);
		int g = fc + random.nextInt(bc - fc);
		int b = fc + random.nextInt(bc - fc);
		return new Color(r, g, b);
	}

	/**
	 * 功能：获取验证码的字符串值
	 * 
	 * @return
	 */
	public String getVerificationCodeValue() {
		return this.getStr();
	}

	/**
	 * 功能：取得验证码图片
	 * 
	 * @return
	 */
	public ByteArrayInputStream getImage() {
		return this.image;
	}

	public String getStr() {
		return str;
	}

	public void setStr(String str) {
		this.str = str;
	}

	public void setImage(ByteArrayInputStream image) {
		this.image = image;
	}
}

struts2中获得验证码：

	/**
	 * 功能：打开login.jsp的时候获得随机的验证码图片
	 * 
	 * @return
	 */
	public String getRandomPictrue() {
		VerificationCodeUtil vcu = VerificationCodeUtil.Instance();
		this.setInputStream(vcu.getImage());
		this.setSessionAttribute("random", vcu.getVerificationCodeValue());// 取得随机字符串放入HttpSession
		return SUCCESS;

	}

另外前台jsp页面

  <script type="text/javascript">   
    function changeValidateCode(obj) {   
           //获取当前的时间作为参数，无具体意义   
        var timenow = new Date().getTime();   
           //每次请求需要一个不同的参数，否则可能会返回同样的验证码   
        //这和浏览器的缓存机制有关系，也可以把页面设置为不缓存，这样就不用这个参数了。   
        obj.src="getRandomPictrue?d="+timenow;   
    }   
</script>
<tr>
                <td height="24" valign="bottom"><div align="right"><span class="STYLE3">验证码</span></div></td>
                <td width="10" valign="bottom">&nbsp;</td>
                <td width="52" height="24" valign="bottom"><input type="text"  maxlength=4 name="yzm" id="textfield3" style="width:50px; height:17px; background-color:#87adbf; border:solid 1px #153966; font-size:12px; color:#283439; "></td>
                <td width="92" valign="bottom"><div align="center"><img src="getRandomPictrue.action" width="80" height="20" onclick="changeValidateCode(this)"></div></td>
              </tr> 

另外，在登录的时候，后台验证验证码是否输入正确

public String userLogin() {
		String yanzhengma = this.getYzm().toLowerCase();//将验证码字符串全部转换成小写
		String random = getSessionAttribute("random").toString().toLowerCase();		 
		if(!yanzhengma.equals(random)){
			this.setRequestAttribute("errorMessage", "验证码错误，请核实后重新输入");
			return INPUT;
		}
		else{
			UserModel user = getUserService().loginJudge(getUserName(),
					getUserPass());
			if (user != null) {
				getSession().setAttribute("user", user);
				getSession().setAttribute("userId", user.getUserId());
				List<PermissionModel> treeList = userService.getTree(user
						.getUserId());
				getRequest().setAttribute("treeList", treeList);
				this.setRequestAttribute("username", user.getUserName());
				user.setLastLoginTime(DateUtil.getCurrentTimestamp());
				if (userService.addUser(user)) {
					logger.info(getUserName() + "登录成功");
					return SUCCESS;
				} else {
					logger.info(getUserName() + "登录失败，失败原因，更新lastLoginTime失败");
					this.setRequestAttribute("errorMessage", "服务器hold不住啦，请稍后重新登录");
					return INPUT;
				}
			} else {
				logger.info(getUserName() + "登录失败，用户名或者密码不正确");
				this.setRequestAttribute("errorMessage", "登录失败，用户名或者密码不正确");
				return INPUT;
			}
		}
		
	}

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