Java 验证码生成

package com.servlet;import java.awt.Color;import java.awt.Font;import java.awt.Graphics;import java.awt.image.BufferedImage;import java.io.IOException;import java.io.OutputStream;import java.io.PrintWriter;import java.util.Random;import javax.imageio.ImageIO;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import javax.servlet.http.HttpSession;import com.sun.image.codec.jpeg.JPEGCodec;import com.sun.image.codec.jpeg.JPEGImageEncoder;public class Code extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest request,HttpServletResponse response) throws ServletException, IOException {HttpSession session = request.getSession();OutputStream out = response.getOutputStream();String s = "";int intCount = 0;/** * 验证码宽度 */int width = 100;/** * 验证码高度 */int height = 25;/** * 验证码字符集 */char[] code = new char[] { 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I','J', 'K', 'L', 'M', 'N', 'P', 'Q', 'R', 'S', 'T', 'U', 'V','W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h','i', 'j', 'k', 'm', 'n', 'p', 'q', 'r', 's', 't', 'u','v', 'w', 'x', 'y', 'z', '2', '3', '4', '5', '6', '7', '8', '9' };/** * 创建一个随机数生成器类 */Random random = new Random();// 随机产生codeCount数字的验证码。for (int i = 0; i < 4; i++) {// 得到随机产生的验证码数字。String strRand = String.valueOf(code[random.nextInt(code.length)]);// 将产生的四个随机数组合在一起。s = s + strRand;}// 保存入session,用于与用户的输入进行比较.// 注意比较完之后清除session.session.setAttribute("validateCode", s);response.setContentType("image/gif");// 定义图像bufferBufferedImage image = new BufferedImage(width, height,BufferedImage.TYPE_INT_RGB);Graphics gra = image.createGraphics();// 将图像填充为白色gra.setColor(Color.WHITE);gra.fillRect(0, 0, width, height);// 创建字体，字体的大小应该根据图片的高度来定。// 字体对象构造方法public Font(String familyName,int style,int size)// familyName字体名；字体名可以分成两大类：中文字体：宋体、楷体、黑体等；英文字体：Arial、Times New Roman等等；// style风格。PLAIN普通字体，BOLD（加粗），ITALIC（斜体），Font.BOLD+ Font.ITALIC（粗斜体）// size 大小Font font = new Font("宋体", Font.BOLD + Font.ITALIC, height - 1);//// 设置字体。gra.setFont(font);// 画边框。gra.setColor(getColor());gra.drawRect(0, 0, width - 1, height - 1);// 随机产生干扰线，使图象中的认证码不易被其它程序探测到。gra.setColor(Color.BLACK);for (int i = 0; i < 50; i++) {int x = random.nextInt(width);int y = random.nextInt(height);int xl = random.nextInt(5);int yl = random.nextInt(5);gra.setColor(getColor());gra.drawLine(x, y, x + xl, y + yl);}// 输出数字char c;for (int i = 0; i < 4; i++) {c = s.charAt(i);gra.drawString(c + "", i * 25 + 4, 20); // 25为宽度，11为上下高度位置}OutputStream toClient = response.getOutputStream();JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(toClient);encoder.encode(image);toClient.close();out.flush();out.close();}private Color getColor() {Random random = new Random();int red = 0, green = 0, blue = 0;// 产生随机的颜色分量来构造颜色值，这样输出的每位数字的颜色值都将不同。red = random.nextInt(200);green = random.nextInt(200);blue = random.nextInt(200);return new Color(red, green, blue);}}