简单验证码生成——Java版

来源：互联网发布：windows下获取ntp时间编辑：程序博客网时间：2024/06/16 03:42

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"> //刷新验证码的js函数  function changeCode() {  var imgNode = document.getElementById("vimg");                  //重新加载验证码，达到刷新的目的  imgNode.src = "servlet/AuthImageServlet?t=" + Math.random();  // 防止浏览器缓存的问题     }        </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。