Java实现验证码图片

这样的实现方式对JDK版本有要求。
 1 package edu.cloud.editmap.utils;

 2 

 3 import java.awt.Color;

 4 import java.awt.Font;

 5 import java.awt.Graphics2D;

 6 import java.awt.image.BufferedImage;

 7 import java.io.IOException;

 8 import java.util.Random;

 9 

10 import javax.servlet.ServletOutputStream;

11 import javax.servlet.http.HttpServletRequest;

12 import javax.servlet.http.HttpServletResponse;

13 

14 import com.sun.image.codec.jpeg.JPEGCodec;

15 import com.sun.image.codec.jpeg.JPEGImageEncoder;

16 

17 public class IdentityCode {

18     private static final long serialVersionUID = -479885884254942306L;

19 

20     public static final char[] CHARS = { '2', '3', '4', '5', '6', '7', '8',

21             '9', 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'J', 'K', 'L', 'M',

22             'N', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z' };

23 

24     public static Random random = new Random();

25 

26     public static String getRandomString() {

27         StringBuffer buffer = new StringBuffer();

28         for (int i = 0; i < 4; i++) {

29             buffer.append(CHARS[random.nextInt(CHARS.length)]);

30         }

31         return buffer.toString();

32     }

33 

34     public static Color getRandomColor() {

35         return new Color(random.nextInt(255), random.nextInt(255), random

36                 .nextInt(255));

37     }

38 

39     public static Color getReverseColor(Color c) {

40         return new Color(255 - c.getRed(), 255 - c.getGreen(), 255 - c

41                 .getBlue());

42     }

43 

44     public static void createImage(HttpServletResponse response,HttpServletRequest request){

45 

46 

47         response.setContentType("image/jpeg");

48         

49         String randomString = getRandomString();

50         System.out.println(randomString);

51         

52         request.getSession().setAttribute("indentity_code", randomString);

53         

54         int width = 100;

55         int height = 30;

56 

57         Color color = getRandomColor();

58         Color reverse = getReverseColor(color);

59 

60         BufferedImage bi = new BufferedImage(width, height,

61                 BufferedImage.TYPE_INT_RGB);

62         Graphics2D g = bi.createGraphics();

63         g.setFont(new Font(Font.SANS_SERIF, Font.BOLD, 16));

64         g.setColor(color);

65         g.fillRect(0, 0, width, height);

66         g.setColor(reverse);

67         g.drawString(randomString, 18, 20);

68         for (int i = 0, n = random.nextInt(100); i < n; i++) {

69             g.drawRect(random.nextInt(width), random.nextInt(height), 1, 1);

70         }

71         

72         // 转成JPEG格式

73         try {

74             

75             ServletOutputStream out = response.getOutputStream();

76             JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(out);

77             encoder.encode(bi);

78             out.flush();

79             

80         } catch (IOException e) {

81             e.printStackTrace();

82         }

83         

84     }

85 

86 }