生成随机图片验证码

来源：互联网发布：zepto.js tap事件编辑：程序博客网时间：2024/06/14 09:49
项目中，生成随机图片验证码代码：先保存，后学习：
package cn.digitalpublishing.servlet;import java.awt.Color;import java.awt.Font;import java.awt.Graphics;import java.awt.image.BufferedImage;import java.io.ByteArrayOutputStream;import java.io.IOException;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;import cn.digitalpublishing.springmvc.controller.system.CommonController;//import cn.com.daxtech.framework.security.UidPwdAuthenticationFilter;@SuppressWarnings("serial")public class CheckCode extends HttpServlet{private static int WIDTH = 60;private static int HEIGHT = 20;public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {HttpSession session = request.getSession();response.setContentType("image/jpeg");ServletOutputStream sos = response.getOutputStream();// 设置浏览器不要缓存此图片 response.setHeader("Pragma", "No-cache");response.setHeader("Cache-Control", "no-cache");response.setDateHeader("Expires", 0);// 创建内存图象并获得其图形上下文 BufferedImage image = new BufferedImage(WIDTH, HEIGHT,BufferedImage.TYPE_INT_RGB);Graphics g = image.getGraphics();// 产生随机的认证码 char[] rands = generateCheckCode();// 产生图像 drawBackground(g);drawRands(g, rands);// 结束图像 的绘制 过程， 完成图像 g.dispose();// 将图像输出到客户端 ByteArrayOutputStream bos = new ByteArrayOutputStream();ImageIO.write(image, "JPEG", bos);byte[] buf = bos.toByteArray();response.setContentLength(buf.length);// 下面的语句也可写成： bos.writeTo(sos); sos.write(buf);bos.close();sos.close();// 将当前验证码存入到 Session 中 session.setAttribute(CommonController.VALIDATE_CODE, new String(rands));//session.setAttribute(UidPwdAuthenticationFilter.VALIDATE_CODE, new String(rands));// 直接使用下面的代码将有问题， Session 对象必须在提交响应前获得 //request.getSession().setAttribute("check_code",new String(rands)); }private char[] generateCheckCode() {// 定义验证码的字符表 String chars = "2345678abcdefghjkmnprstuwxz";char[] rands = new char[4];for (int i = 0; i < 4; i++) {int rand = (int) (Math.random() * chars.length());rands[i] = chars.charAt(rand);}return rands;}private void drawRands(Graphics g, char[] rands) {g.setColor(Color.BLACK);g.setFont(new Font(null, Font.ITALIC | Font.BOLD, 18));// 在不同的高度上输出验证码的每个字符          g.drawString("" + rands[0], 1, 17);g.drawString("" + rands[1], 16, 15);g.drawString("" + rands[2], 31, 18);g.drawString("" + rands[3], 46, 16);// System.out.println(rands); }private void drawBackground(Graphics g) {// 画背景 g.setColor(new Color(0xDCDCDC));g.fillRect(0, 0, WIDTH, HEIGHT);// 随机产生 120 个干扰点 for (int i = 0; i < 120; i++) {int x = (int) (Math.random() * WIDTH);int y = (int) (Math.random() * HEIGHT);int red = (int) (Math.random() * 255);int green = (int) (Math.random() * 255);int blue = (int) (Math.random() * 255);g.setColor(new Color(red, green, blue));g.drawOval(x, y, 1, 0);}}}
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