1 importjava.awt.Color;2 importjava.awt.Font;3 importjava.awt.Graphics;4 importjava.awt.image.BufferedImage;5 importjava.util.Random;6 importjavax.imageio.ImageIO;7 importjavax.servlet.http.HttpServletRequest;8 importjavax.servlet.http.HttpServletResponse;9 importjavax.servlet.http.HttpSession;10
11
19 public classCaptcha {20
21 public static final String RANDOMCODEKEY = "sess_captcha";//放到session中的key
22 private Random random = newRandom();23 private String randString = "0123456789";//随機産生的字元串
24
25 private int width = 80;//圖檔寬
26 private int height = 26;//圖檔高
27 private int lineSize = 40;//幹擾線數量
28 private int stringNum = 4;//随機産生字元數量
29
30
33 privateFont getFont() {34 return new Font("Fixedsys", Font.CENTER_BASELINE, 18);35 }36
37
40 private Color getRandColor(int fc, intbc) {41 if (fc > 255)42 fc = 255;43 if (bc > 255)44 bc = 255;45 int r = fc + random.nextInt(bc - fc - 16);46 int g = fc + random.nextInt(bc - fc - 14);47 int b = fc + random.nextInt(bc - fc - 18);48 return newColor(r, g, b);49 }50
51
54 private String drowString(Graphics g, String randomString, inti) {55 g.setFont(getFont());56 g.setColor(new Color(random.nextInt(101), random.nextInt(111), random.nextInt(121)));57 String rand =String.valueOf(getRandomString(random.nextInt(randString.length())));58 randomString +=rand;59 g.translate(random.nextInt(3), random.nextInt(3));60 g.drawString(rand, 13 * i, 16);61 returnrandomString;62 }63
64
67 private voiddrowLine(Graphics g) {68 int x =random.nextInt(width);69 int y =random.nextInt(height);70 int xl = random.nextInt(13);71 int yl = random.nextInt(15);72 g.drawLine(x, y, x + xl, y +yl);73 }74
75
78 public String getRandomString(intnum) {79 returnString.valueOf(randString.charAt(num));80 }81
82
83
86 public voidgetRandcode(HttpServletRequest request, HttpServletResponse response) {87 HttpSession session =request.getSession();88 //BufferedImage類是具有緩沖區的Image類,Image類是用于描述圖像資訊的類
89 BufferedImage image = newBufferedImage(width, height, BufferedImage.TYPE_INT_BGR);90 Graphics g = image.getGraphics();//産生Image對象的Graphics對象,改對象可以在圖像上進行各種繪制操作
91 g.fillRect(0, 0, width, height);92 g.setFont(new Font("Times New Roman", Font.ROMAN_BASELINE, 18));93 g.setColor(getRandColor(110, 133));94 //繪制幹擾線
95 for (int i = 0; i <= lineSize; i++) {96 drowLine(g);97 }98 //繪制随機字元
99 String randomString = "";100 for (int i = 1; i <= stringNum; i++) {101 randomString =drowString(g, randomString, i);102 }103 session.removeAttribute(RANDOMCODEKEY);104 session.setAttribute(RANDOMCODEKEY, randomString);105 g.dispose();106 try{107 ImageIO.write(image, "JPEG", response.getOutputStream());//将記憶體中的圖檔通過流動形式輸出到用戶端
108 } catch(Exception e) {109 e.printStackTrace();110 }111 }112 }