简单验证码生成Java版

验证码大家都知道,它的作用也不用我多说了吧。如果不太清楚请参见百度百科中的解释,一般验证码的生成就是随机产生字符(数字、字母或者汉字等),然后将这些生成的字符绘制成一张图片,再在图片上加上一些干扰元素,如各种线条之类的。好了废话不多说一起往下看:

简单的登录页面(代码并不完整,只有验证码部分)

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%> 
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> 
<html> 
 <head> 
 <title>验证码</title> 
 <script type="text/javascript"> 
<span style="white-space:pre" data-filtered="filtered"></span><span style="white-space:pre"> </span> //刷新验证码的js函数 
<span style="white-space:pre"> </span>function changeCode() { 
<span style="white-space:pre"> </span>var imgNode = document.getElementById("vimg");   
 
<span style="white-space:pre"> </span>//重新加载验证码,达到刷新的目的 
<span style="white-space:pre"> </span>imgNode.src = "servlet/AuthImageServlet?t=" + Math.random(); // 防止浏览器缓存的问题 
<span style="white-space:pre"> </span>} 
 </script> 
 </head> 
 <body> 
 <form action="checkServlet" method="post"> 
 <label>输入验证码</label><br/> 
 <input type="text" name="randomCode"/><img id="vimg" title="点击更换" onclick="changeCode();" src="servlet/AuthImageServlet"><br/> 
 <input type="submit" value="submit"> 
 </form> 
 </body> 
</html> 

通过session.getAttribute("rand"),获得生成的验证码,然后跟用户输入的进行比较,再根据比较结果做相应的处理。

通过servlet生成验证码:

package com.util.servlet; 
 
import java.awt.Color; 
import java.awt.Font; 
import java.awt.Graphics; 
import java.awt.image.BufferedImage; 
import java.io.IOException; 
import java.util.Random; 
 
import javax.imageio.ImageIO; 
import javax.servlet.ServletException; 
import javax.servlet.http.HttpServlet; 
import javax.servlet.http.HttpServletRequest; 
import javax.servlet.http.HttpServletResponse; 
import javax.servlet.http.HttpSession; 
 
public class AuthImageServlet extends HttpServlet { 
 
 private static final String CONTENT_TYPE = "text/html; charset=gb2312"; 
 //设置字母的大小,大小 
 private Font mFont = new Font("Times New Roman", Font.PLAIN, 17); 
 public void init() throws ServletException 
 { 
 super.init(); 
 } 
 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); 
 } 
 
 public void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException 
 { 
 response.setHeader("Pragma","No-cache"); 
 response.setHeader("Cache-Control","no-cache"); 
 response.setDateHeader("Expires", 0); 
 //表明生成的响应是图片 
 response.setContentType("image/jpeg"); 
  
 int width=100, height=18; 
 BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB); 
  
 Graphics g = image.getGraphics(); 
 Random random = new Random(); 
 g.setColor(getRandColor(200,250)); 
 g.fillRect(1, 1, width-1, height-1); 
 g.setColor(new Color(102,102,102)); 
 g.drawRect(0, 0, width-1, height-1); 
 g.setFont(mFont); 
 
 g.setColor(getRandColor(160,200)); 
 
 //画随机线 
 for (int i=0;i<155;i++) 
 { 
  int x = random.nextInt(width - 1); 
  int y = random.nextInt(height - 1); 
  int xl = random.nextInt(6) + 1; 
  int yl = random.nextInt(12) + 1; 
  g.drawLine(x,y,x + xl,y + yl); 
 } 
 
 //从另一方向画随机线 
 for (int i = 0;i < 70;i++) 
 { 
  int x = random.nextInt(width - 1); 
  int y = random.nextInt(height - 1); 
  int xl = random.nextInt(12) + 1; 
  int yl = random.nextInt(6) + 1; 
  g.drawLine(x,y,x - xl,y - yl); 
 } 
 
 //生成随机数,并将随机数字转换为字母 
 String sRand=""; 
 for (int i=0;i<6;i++) 
 { 
  int itmp = random.nextInt(26) + 65; 
  char ctmp = (char)itmp; 
  sRand += String.valueOf(ctmp); 
  g.setColor(new Color(20+random.nextInt(110),20+random.nextInt(110),20+random.nextInt(110))); 
  g.drawString(String.valueOf(ctmp),15*i+10,16); 
 } 
 
 HttpSession session = request.getSession(true); 
 session.setAttribute("rand",sRand); 
 g.dispose(); 
 ImageIO.write(image, "JPEG", response.getOutputStream()); 
 } 
 
} 

web.xml中的servlet配置信息:

<?xml version="1.0" encoding="UTF-8"?> 
<web-app version="2.5" 
 xmlns="http://java.sun.com/xml/ns/javaee" 
 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
 xsi:schemaLocation="http://java.sun.com/xml/ns/javaee 
 http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"> 
 
 <servlet> 
 <servlet-name>AuthImageServlet</servlet-name> 
 <servlet-class>com.util.servlet.AuthImageServlet</servlet-class> 
 </servlet> 
 <servlet-mapping> 
 <servlet-name>AuthImageServlet</servlet-name> 
 <url-pattern>/servlet/AuthImageServlet</url-pattern> 
 </servlet-mapping> 
 
 <welcome-file-list> 
 <welcome-file>index.jsp</welcome-file> 
 </welcome-file-list> 
</web-app> 

就这样验证码的功能就实现了,很简单、很实用。当然还有更加美观,更加严密的方式,有兴趣的朋友可以深入研究。这里就跟大家分享一个比较简单的方式。欢迎各位批评指正。

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呐喊教程。

声明:本文内容来源于网络,版权归原作者所有,内容由互联网用户自发贡献自行上传,本网站不拥有所有权,未作人工编辑处理,也不承担相关法律责任。如果您发现有涉嫌版权的内容,欢迎发送邮件至:notice#nhooo.com(发邮件时,请将#更换为@)进行举报,并提供相关证据,一经查实,本站将立刻删除涉嫌侵权内容。