package org.yeeku.web;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.ServletOutputStream;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import javax.servlet.http.HttpSession;public class AuthImg extends HttpServlet { protected void processRequest(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { response.setContentType("image/jpeg"); response.setHeader("Pragma","No-cache"); response.setHeader("Cache-Control","no-cache"); response.setDateHeader("Expires", 0); HttpSession session=request.getSession(); // 在内存中创建图象 int width=60, height=20; BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB); // 获取图形上下文 Graphics g = image.getGraphics(); //生成随机类 Random random = new Random(); // 设定背景色 g.setColor(getRandColor(200,250)); g.fillRect(0, 0, width, height); //设定字体 g.setFont(new Font("Times New Roman",Font.PLAIN,18)); //画边框 //g.setColor(new Color()); //g.drawRect(0,0,width-1,height-1); // 随机产生155条干扰线，使图象中的认证码不易被其它程序探测到 g.setColor(getRandColor(160,200)); for (int i=0;i<155;i++) { int x = random.nextInt(width); int y = random.nextInt(height); int xl = random.nextInt(12); int yl = random.nextInt(12); g.drawLine(x,y,x+xl,y+yl); } // 取随机产生的认证码(4位数字) String sRand=""; for (int i=0;i<6;i++){ String rand=String.valueOf(random.nextInt(10)); sRand+=rand; // 将认证码显示到图象中 g.setColor(new Color(20+random.nextInt(110),20+random.nextInt(110),20+random.nextInt(110)));//调用函数出来的颜色相同，可能是因为种子太接近，所以只能直接生成 g.drawString(rand,13*i+6,16); } // 将认证码存入SESSION session.setAttribute("rand",sRand); // 图象生效 g.dispose(); ServletOutputStream responseOutputStream =response.getOutputStream(); // 输出图象到页面 ImageIO.write(image, "JPEG", responseOutputStream); //以下关闭输入流！ responseOutputStream.flush(); responseOutputStream.close(); } Color getRandColor(int fc,int bc){//给定范围获得随机颜色 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); } // <editor-fold defaultstate="collapsed" desc="HttpServlet methods. Click on the + sign on the left to edit the code."> protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { processRequest(request, response); } protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { processRequest(request, response); } public String getServletInfo() { return "Short description"; } // </editor-fold>} //产生的验证码有字母的Servletpublic class AuthImg extends HttpServlet{ private Font mFont = new Font("Arial Black", Font.PLAIN, 16); 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); 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)); 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); } 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); } String sRand=""; for (int i=0;i<6;i++) { String tmp = getRandomChar(); sRand += tmp; g.setColor(new Color(20+random.nextInt(110),20+random.nextInt(110),20+random.nextInt(110))); g.drawString(tmp,15*i+10,15); } HttpSession session = request.getSession(true); session.setAttribute("rand",sRand); g.dispose(); ImageIO.write(image, "JPEG", response.getOutputStream()); } private String getRandomChar() { int rand = (int)Math.round(Math.random() * 2); long itmp = 0; char ctmp = '\'; switch (rand) { case 1: itmp = Math.round(Math.random() * 25 + 65); ctmp = (char)itmp; return String.valueOf(ctmp); case 2: itmp = Math.round(Math.random() * 25 + 97); ctmp = (char)itmp; return String.valueOf(ctmp); default : itmp = Math.round(Math.random() * 9); return String.valueOf(itmp); } } 第二步,在工程中的web.xml中配置上面的servlet<?xml version="1.0" encoding="UTF-8"?><web-app version="2.4" xmlns="http://java.sun.com/xml/ns/j2ee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd"> <servlet> <servlet-name>img</servlet-name> <servlet-class>org.yeeku.web.AuthImg</servlet-class> </servlet> <servlet-mapping> <servlet-name>img</servlet-name> <url-pattern>/authImg</url-pattern> </servlet-mapping> <welcome-file-list> <welcome-file>index.jsp</welcome-file> </welcome-file-list></web-app>第三步,编写验证码显示的jsp页面:<%@ page contentType="text/html;charset=gb2312"%><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html> <head> <title>认证码输入页面</title> <meta http-equiv="Content-Type" content="text/html; charset=gb2312"> <META HTTP-EQUIV="Pragma" CONTENT="no-cache"> <META HTTP-EQUIV="Cache-Control" CONTENT="no-cache"> <META HTTP-EQUIV="Expires" CONTENT="0"> <script language="JavaScript"> function myrefresh() { window.location.reload(); }</script> </head> <body> <form method=post action="check.jsp"> <table> <tr> <td align=left> 系统产生的认证码： </td> <td> <img border=0 src="authImg"> <input type="button" value="看不清，在换一张" onclick="myrefresh()"> </td> </tr> <tr> <td align=left> 输入上面的认证码： </td> <td> <input type=text name=rand maxlength=4 value=""> </td> </tr> <tr> <td colspan=2 align=center> <input type=submit value="提交检测"> </td> </tr> </table> </form> </body>第四步,编写jsp测试验证码<%@ page contentType="text/html; charset=gb2312" language="java" import="java.sql.*" errorPage="" %><html><head><title>认证码验证页面</title><meta http-equiv="Content-Type" content="text/html; charset=gb2312"><META HTTP-EQUIV="Pragma" CONTENT="no-cache"><META HTTP-EQUIV="Cache-Control" CONTENT="no-cache"><META HTTP-EQUIV="Expires" CONTENT="0"></head><body><%String rand = (String)session.getAttribute("rand");String input = request.getParameter("rand");%>系统产生的认证码为： <%= rand %><br>您输入的认证码为： <%= input %><br><br><% if (rand.equals(input)) {%><font color=green>输入相同，认证成功！</font><% } else {%><font color=red>输入不同，认证失败！</font><% }%></body></html>
