生成随机验证码

image.jsp的内容如下：

<%@page import="javax.imageio.ImageIO"%><%@page import="java.awt.Font"%><%@page import="java.awt.Graphics"%><%@page import="java.awt.image.BufferedImage"%><%@page import="java.util.Random"%><%@page import="java.awt.Color"%><%@ page import="org.springframework.web.context.support.WebApplicationContextUtils" %><%@ page import="org.springframework.context.ApplicationContext" %><%@ page import="redis.clients.jedis.ShardedJedisPool" %><%@ page import="redis.clients.jedis.ShardedJedis" %><%@ page language="java" contentType="image/JPEG; charset=UTF-8"pageEncoding="UTF-8"%><%!//获取随机颜色  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);}%><%//设置页面不缓存   response.setHeader("Pragma", "No-cache");response.setHeader("Cache-Control", "no-cache");response.setDateHeader("Expires", 0);//在内存中创建图像  int width = 60;int height = 20;BufferedImage image = new BufferedImage(width, height,BufferedImage.TYPE_INT_RGB);//获取图形上下文  Graphics g = image.getGraphics();//随机类  Random random = new Random();//设定背景  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));//随机产生干扰线  g.setColor(getRandColor(160, 200));for (int i = 0; i < 100; 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);}//随机产生4位验证码  String[] codes = { "2", "3", "4", "5", "6", "7", "8", "9", "A","B", "C", "D", "E", "F", "G", "H", "J", "K", "L", "M", "N","P", "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z" };String code = "";for (int i = 0; i < 4; i++) {String str = codes[random.nextInt(codes.length)];code += str;// 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(str, 13 * i + 6, 16);}ServletContext context = request.getSession().getServletContext();//ApplicationContext ctx = WebApplicationContextUtils.getWebApplicationContext(context);//ShardedJedisPool shardedJedisPool = (ShardedJedisPool)ctx.getBean("shardedJedisPool");//ShardedJedis jedis = shardedJedisPool.getResource();// 将认证码存入SESSIONsession.setAttribute("verify", code);//保存到缓存中//jedis.set(session.getId(),code);//jedis.expire(session.getId(),60*2);//shardedJedisPool.returnResource(jedis);// 图象生效     g.dispose();// 输出图象到页面     ImageIO.write(image, "JPEG", response.getOutputStream());//加上下面代码,运行时才不会出现java.lang.IllegalStateException: getOutputStream() has already been called ..........等异常  response.getOutputStream().flush();response.getOutputStream().close();response.flushBuffer();out.clear();out = pageContext.pushBody();%>

jsp页面：

<input type="text" name="verify" id="verify" class="input-medium"placeholder="验证码"> <img id="image" border="0" onclick="refresh()" src="<%=request.getContextPath()%>/user/verifyImage.htm"title="点击更换图片" /><p id="verifyS" class="flagS"></p>

服务器端：

@Controller("user.userController")@RequestMapping("/user")public class UserController{private Logger log = Logger.getLogger(getClass());@Autowiredprivate UserService userService;/**     * @描述：获得验证码图片     * @开发人员: chb     * @开发日期：2014年11月24日下午3:27:40     */    @RequestMapping(value = "/verifyImage")    public String getVerifyImage(Model model) {        return "public/image";    }