验证码HttpServlet

 ?1 package servlet; ?2 import java.awt.Color; ?3 import java.awt.Font; ?4 import java.awt.Graphics; ?5 import java.awt.Graphics2D; ?6 import java.awt.image.BufferedImage; ?7 import java.io.IOException; ?8 import java.util.Random; ?9 import javax.imageio.ImageIO; 10 import javax.servlet.ServletException; 11 import javax.servlet.http.HttpServlet; 12 import javax.servlet.http.HttpServletRequest; 13 import javax.servlet.http.HttpServletResponse; 14 /** 15 ?* 通过javaAPI在内存中生成一张图片。 16 ?* 通过response的输出流响应给客户端。 17 ?*/ 18 public class CheckCode extends HttpServlet { 19 ????public void doGet(HttpServletRequest request, HttpServletResponse response) 20 ????????????throws ServletException, IOException { 21 ????????// 禁止缓存 22 ????????// response.setHeader("Cache-Control", "no-cache"); 23 ????????// response.setHeader("Pragma", "no-cache"); 24 ????????// response.setDateHeader("Expires", -1); 25 ????????int width = 120; 26 ????????int height = 30; 27 ????????// 步骤一 绘制一张内存中图片 28 ????????BufferedImage bufferedImage = new BufferedImage(width, height, 29 ????????????????BufferedImage.TYPE_INT_RGB); 30 ????????// 步骤二 图片绘制背景颜色 ---通过绘图对象 31 ????????Graphics graphics = bufferedImage.getGraphics();// 得到画图对象 --- 画笔 32 ????????// 绘制任何图形之前 都必须指定一个颜色 33 ????????graphics.setColor(getRandColor(200, 250)); 34 ????????graphics.fillRect(0, 0, width, height); 35 ????????// 步骤三 绘制边框 36 ????????graphics.setColor(Color.WHITE); 37 ????????graphics.drawRect(0, 0, width - 1, height - 1); 38 ????????// 步骤四 四个随机数字 39 ????????Graphics2D graphics2d = (Graphics2D) graphics; 40 ????????// 设置输出字体 41 ????????graphics2d.setFont(new Font("宋体", Font.BOLD, 18)); 42 ????????String words = 43 ?????????"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz1234567890"; 44 ????????Random random = new Random();// 生成随机数 45 ????????// 将随机生成的验证码保存到session: 46 ????????StringBuffer buffer = new StringBuffer(); 47 ????????// 定义x坐标 48 ????????int x = 10; 49 ????????for (int i = 0; i < 4; i++) { 50 ????????????// 随机颜色 51 ????????????graphics2d.setColor(new Color(20 + random.nextInt(110), 20 + random 52 ????????????????????.nextInt(110), 20 + random.nextInt(110))); 53 ????????????// 旋转 -30 --- 30度 54 ????????????int jiaodu = random.nextInt(60) - 30; 55 ????????????// 换算弧度 56 ????????????double theta = jiaodu * Math.PI / 180; 57 ????????????// 生成一个随机数字 58 ????????????int index = random.nextInt(words.length()); // 生成随机数 0 到 length - 1 59 ????????????// 获得字母数字 60 ????????????char c = words.charAt(index); 61 ????????????// 将生成汉字 加入buffer 62 ????????????buffer.append(c); 63 ????????????// 将c 输出到图片 64 ????????????graphics2d.rotate(theta, x, 20); 65 ????????????graphics2d.drawString(String.valueOf(c), x, 20); 66 ????????????graphics2d.rotate(-theta, x, 20); 67 ????????????x += 30; 68 ????????} 69 ????????//Jis1 存储到Session 70 ????????request.getSession().setAttribute("code", buffer.toString()); 71 ????????System.out.print("存储在Session中。"); 72 ????????System.out.println(buffer.toString()); 73 ????????// 步骤五 绘制干扰线 74 ????????graphics.setColor(getRandColor(160, 200)); 75 ????????int x1; 76 ????????int x2; 77 ????????int y1; 78 ????????int y2; 79 ????????for (int i = 0; i < 30; i++) { 80 ????????????x1 = random.nextInt(width); 81 ????????????x2 = random.nextInt(12); 82 ????????????y1 = random.nextInt(height); 83 ????????????y2 = random.nextInt(12); 84 ????????????graphics.drawLine(x1, y1, x1 + x2, x2 + y2); 85 ????????} 86 ????????// 将上面图片输出到浏览器 ImageIO 87 ????????graphics.dispose();// 释放资源 88 ????????ImageIO.write(bufferedImage, "jpg", response.getOutputStream()); 89 ????} 90 ????public void doPost(HttpServletRequest request, HttpServletResponse response) 91 ????????????throws ServletException, IOException { 92 ????????doGet(request, response); 93 ????} 94 ????/** 95 ?????* 取其某一范围的color 96 ?????* @param fc 97 ?????* ???????????int 范围参数1 98 ?????* @param bc 99 ?????* ???????????int 范围参数2100 ?????* @return Color101 ?????*/102 ????private Color getRandColor(int fc, int bc) {103 ????????// 取其随机颜色104 ????????Random random = new Random();105 ????????if (fc > 255) {106 ????????????fc = 255;107 ????????}108 ????????if (bc > 255) {109 ????????????bc = 255;110 ????????}111 ????????int r = fc + random.nextInt(bc - fc);112 ????????int g = fc + random.nextInt(bc - fc);113 ????????int b = fc + random.nextInt(bc - fc);114 ????????return new Color(r, g, b);115 ????}116 }