简单验证码生成Java版_Java教程

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：

简单验证码生成Java版

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>