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Jsp servlet验证码工具类分享

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：

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持硕编程。

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