Jsp servlet验证码工具类分享

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昨晚在csdn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，以供大家做个参考。

1、添加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,字体大小根据图片高度决定 
  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，增加识别系统难度 
   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访问servlet,通过response响应一个图像流 
 <a href="##" rel="external nofollow" 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>

4、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("下面开始 做其他业务操作...."); 
 }

校验图如下：