Servlet生成验证码

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.annotation.WebServlet;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;/** * 生成验证码图片 */@WebServlet("/imgcode")public class ImgCodeServlet extends HttpServlet {private static final long serialVersionUID = 1L;public static final String ImgCode = "imgcode";// 放到session中的keyprivate Random random = new Random();private String randString = "012346789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";// 随机产生的字符串private int width = 85;// 图片宽private int height = 35;// 图片高private int lineSize = 5;// 干扰线数量private int stringNum = 4;// 随机产生字符数量/* * 获得字体 */private Font getFont() {return new Font("Fixedsys", Font.CENTER_BASELINE, 26);}/* * 获得颜色 */private Color getRandColor(int fc, int bc) {if (fc > 255)fc = 255;if (bc > 255)bc = 255;int r = fc + random.nextInt(bc - fc - 16);int g = fc + random.nextInt(bc - fc - 14);int b = fc + random.nextInt(bc - fc - 18);return new Color(r, g, b);}/** * 生成随机图片 */private void getRandcode(HttpServletRequest request, HttpServletResponse response) {// BufferedImage类是具有缓冲区的Image类,Image类是用于描述图像信息的类BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_BGR);Graphics g = image.getGraphics();// 产生Image对象的Graphics对象,改对象可以在图像上进行各种绘制操作g.fillRect(0, 0, width, height);g.setColor(Color.CYAN);g.drawRect(0, 0, width - 1, height - 1);g.setFont(new Font("Times New Roman", Font.ROMAN_BASELINE, 23));g.setColor(getRandColor(110, 133));// 绘制干扰线for (int i = 0; i <= lineSize; i++) {drawLine(g);}// 绘制随机字符String randomString = "";for (int i = 1; i <= stringNum; i++) {randomString = drawString(g, randomString, i);}request.getSession().setAttribute(ImgCode, randomString);g.dispose();try {ImageIO.write(image, "JPEG", response.getOutputStream());// 将内存中的图片通过流动形式输出到客户端} catch (Exception e) {e.printStackTrace();}}/* * 绘制字符串 */private String drawString(Graphics g, String randomString, int i) {g.setFont(getFont());g.setColor(new Color(random.nextInt(101), random.nextInt(111), random.nextInt(121)));String rand = String.valueOf(getRandomString(random.nextInt(randString.length())));randomString += rand;g.translate(random.nextInt(3), random.nextInt(3));g.drawString(rand, 16 * i - 8, 24);return randomString;}/* * 绘制干扰线 */private void drawLine(Graphics g) {int x = random.nextInt(width);int y = random.nextInt(height);int xl = random.nextInt(23);int yl = random.nextInt(25);g.drawLine(x, y, x + xl, y + yl);}/* * 获取随机的字符 */private String getRandomString(int num) {return String.valueOf(randString.charAt(num));}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);getRandcode(request, response);}}