Jsp+servlet 验证码案例

时间：2023-03-09 19:27:39
Jsp+servlet 验证码案例

昨晚在****看到一位前辈写一个ajax+servlet+jsp验证。顿时心血来潮，在阅读前辈的代码下我亲手体验一下，做了一个验证码生成工具类。以供大家做个參考。

1：加入VeriyCodeUtils类生成验证码图像

package com.servlet;

import java.awt.Color;

import java.awt.Font;

import java.awt.Graphics2D;

import java.awt.image.BufferedImage;

import java.io.OutputStream;

import java.util.Random;

import javax.imageio.ImageIO;

/**

 *

 * @author hubiao

 *		验证码生成器

 * 	用到API

 * 		BufferedImage 创建一个图像

 * 		Graphics2D  绘制

 * 			fillRect(x,y,width,height);背景

 * 			font()字体

 * 			drawRect();边框

 * 			drawLine();线

 * 			drwaString:图像数据

 * 		ImageIO 生成图像

 */

public class VeriyCodeUtils {

	/**

	 * @param output 保存验证图像的流

	 * @return  验证码

	 */

	public static String newVeriyCode(OutputStream output)

	{

		int width = 90;

		int height = 40;

		int codeCount = 5;

		char[] codeSequence = { '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', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9' };  

		//创建图像对象,8位RGB

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

		//通过Crapahices来绘制图像到BufferedImage中

		Graphics2D gra = buffered.createGraphics();

		//设置图片背景：白色

		gra.setColor(Color.WHITE);

		gra.fillRect(0, 0, width, height);

		//设置字体,字体大小依据图片高度决定

		gra.setFont(new Font("Fixedsys",Font.PLAIN,height-2));

		//设置边框：黑色,1cm

		gra.setColor(Color.BLACK);

		gra.drawRect(0, 0, width-1, height-1);

		//生成10条黑色干扰线

		gra.setColor(Color.BLACK);

		Random ran = new Random();

		for(int i = 0; i < 70;i++)

		{

			int x = ran.nextInt(255);

			int y = ran.nextInt(255);

			int x1 = ran.nextInt(255);

			int y1 = ran.nextInt(255);

			gra.drawLine(x, y,x+x1, y+y1);//画直线

		}

		//生成验证码

		StringBuffer sb = new StringBuffer();

		int r = 0,g = 0,b = 0;

		for(int i = 0; i < codeCount; i++)

		{

			String strRand = String.valueOf(codeSequence[ran.nextInt(codeSequence.length)]);

			//对每位验证码都生成不同的颜色。添加识别系统难度

			r = ran.nextInt(255);

			g = ran.nextInt(255);

			b = ran.nextInt(255);

			gra.setColor(new Color(r, g, b));

			gra.drawString(strRand, (i+1)*13, height-4);

			sb.append(strRand);

		}

		try {

			ImageIO.write(buffered, "jpeg", output);

		} catch (Exception e) {

			throw new RuntimeException(e);

		}

		return sb.toString();

	}

}

2：servlet使用验证码

protected void doPost(HttpServletRequest req, HttpServletResponse resp)

			throws ServletException, IOException {

		//禁止图像缓存

        resp.setHeader("Pragma", "no-cache");

        resp.setHeader("Cache-Control", "no-cache");

        resp.setDateHeader("Expires", 0);

        resp.setContentType("image/jpeg");

        //生成验证码图像

		String veriyCode = VeriyCodeUtils.newVeriyCode(resp.getOutputStream());

		//将验证码保存到session中

		HttpSession session = req.getSession();

		session.setAttribute("validateCode", veriyCode);

	}

3：JSP页面使用验证码

</head>

  <script type="text/javascript">

		function createCode()

		{

		 	var t = new Date().getTime();//防止页面缓存。使用时间搓

			var srcImg = document.getElementById("srcImg");

			srcImg.src="/ImgVeifyWeb/vity.do?"+t;

		}

  </script>

  <body>

  	<h1>${requestScope.code}</h1>

  	<img id="srcImg" src="<c:url value="/vity.do"></c:url>" 	/>  #这里使用直接让img訪问servlet,通过response响应一个图像流

  	<a href="##" id="codeId" onclick="createCode()">换一张</a>

  	<form action="<c:url value="/hello.do"></c:url>" method="post">

	  	<input type="text" name="codeVify"/>

	  	<input type="submit" value="提交"/>

  	</form>

  </body>

3：校验验证码

protected void doPost(HttpServletRequest req, HttpServletResponse resp)

			throws ServletException, IOException {

		HttpSession session = req.getSession();

		Object validateCode = session.getAttribute("validateCode");

		System.out.println(validateCode);

		String codeVify = req.getParameter("codeVify");

		if(codeVify==null || codeVify.equals(""))

		{

			req.setAttribute("code","验证证不能为空");

			req.getRequestDispatcher("/index.jsp").forward(req, resp);

			return;

		}else if(!validateCode.toString().equalsIgnoreCase(codeVify))

		{

			req.setAttribute("code","验证证错误");

			req.getRequestDispatcher("/index.jsp").forward(req, resp);

			return;

		}

		System.out.println("以下開始 做其它业务操作....");

	}

校验图例如以下：

Jsp+servlet 验证码案例

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