转发一个servlet生成验证码的代码作为存档
?
?
import javax.servlet.*;import javax.servlet.http.*;import java.io.*;import java.awt.*;import java.awt.image.*;import java.util.*;import javax.imageio.*;/** * @author yeeku.H.lee kongyeeku@163.com * @version 1.0 * <br>Copyright (C), 2005-2008, yeeku.H.Lee * <br>This program is protected by copyright laws. * <br>Program Name: * <br>Date: */public 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 = '\u0000'; 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); } }}?其中这是加了干扰线的了，并且用session来保存验证码了，
在登陆的jsp页面中，应该这样设置
?验证码如图：<img src="authImg" id="authImg"/>看不清？<a href="#" onClick="refresh()">单击此处刷新</a>
然后refesh()函数如下写
?
<script> function refresh() { document.getElementById("authImg").src='authImg?now=' + new Date(); } </script>?之所以在最后加now,是防止浏览器的缓存
最后再在web.xml里配置下servlet
?
<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>?
?
?