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2 100 * @return Color 101 */ 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 }
直接将img的src属性指向该servlet的路径即可产生验证码图片.
使用javascript实现图片的刷新，通过js改变src的属性值，给属性值加上时间戳。?time=new Date().getTime();
