图片验证码的生成
1 package util;
2
3 import javax.imageio.ImageIO;
4 import javax.servlet.ServletException;
5 import javax.servlet.http.HttpServlet;
6 import javax.servlet.http.HttpServletRequest;
7 import javax.servlet.http.HttpServletResponse;
8 import java.awt.*;
9 import java.awt.image.BufferedImage;
10 import java.io.IOException;
11 import java.util.Random;
12
13
14 /**
15 * 描述：
16 *
17 * @author $author$
18 * @version $Revision$
19 */
20 public class PicCheckCode extends HttpServlet {
21
22 private Font mFont = new Font("Arial Black", Font.PLAIN, 15); //设置字体
23 private int lineWidth = 2; //干扰线的长度=1.414*lineWidth
24 private int width = 60; //定义图形大小
25 private int height = 20; //定义图形大小
26 private int count = 200;
27
28 /**
29 * 描述：
30 *
31 * @param fc 描述：
32 * @param bc 描述：
33 *
34 * @return 描述：
35 */
36 private Color getRandColor(int fc, int bc) { //取得给定范围随机颜色
37
38 Random random = new Random();
39
40 if (fc > 255) {
41
42 fc = 255;
43 }
44
45 if (bc > 255) {
46
47 bc = 255;
48 }
49
50 int r = fc + random.nextInt (bc - fc);
51 int g = fc + random.nextInt (bc - fc);
52 int b = fc + random.nextInt (bc - fc);
53
54 return new Color(r, g, b);
55 }
56
57 //处理post
58 public void doPost(HttpServletRequest request, HttpServletResponse response)
59 throws ServletException, IOException {
60
61 doGet (request, response);
62 }
63
64 /**
65 * 描述：
66 *
67 * @param request 描述：
68 * @param response 描述：
69 *
70 * @throws ServletException 描述：
71 * @throws IOException 描述：
72 */
73 public void doGet(HttpServletRequest request, HttpServletResponse response)
74 throws ServletException, IOException {
75
76 //response.reset();
77 //设置页面不缓存
78 response.setHeader ("Pragma", "No-cache");
79 response.setHeader ("Cache-Control", "no-cache");
80 response.setDateHeader ("Expires", 0);
81 response.setContentType ("image/gif");
82
83 // 在内存中创建图象
84 BufferedImage image = new BufferedImage(width, height,
85 BufferedImage.TYPE_INT_RGB);
86
87 // 获取图形上下文
88 Graphics2D g = (Graphics2D) image.getGraphics ();
89
90 //生成随机类
91 Random random = new Random();
92
93 // 设定背景色
94 g.setColor (getRandColor (200, 250)); //---1
95
96 g.fillRect (0, 0, width, height);
97
98 //设定字体
99 g.setFont (mFont);
100
101 //画边框
102 g.setColor (getRandColor (0, 20)); //---2
103 g.drawRect (0, 0, width - 1, height - 1);
104
105 //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
106 for (int i = 0; i < count; i++) {
107
108 g.setColor (getRandColor (150, 200)); //---3
109
110 int x = random.nextInt (width - lineWidth - 1) + 1; //保证画在边框之内
111 int y = random.nextInt (height - lineWidth - 1) + 1;
112 int xl = random.nextInt (lineWidth);
113 int yl = random.nextInt (lineWidth);
114 g.drawLine (x, y, x + xl, y + yl);
115 }
116
117 //取随机产生的认证码(4位数字)
118 String sRand = "";
119
120 for (int i = 0; i < 4; i++) {
121
122 String rand = String.valueOf (random.nextInt (10));
123 sRand += rand;
124
125 // 将认证码显示到图象中,调用函数出来的颜色相同，可能是因为种子太接近，所以只能直接生成
126 g.setColor (new Color(20 + random.nextInt (130),
127 20 + random.nextInt (130), 20 + random.nextInt (130))); //--4--50-100
128
129 g.drawString (rand, (13 * i) + 6, 16);
130
131
132 }
133
134 // 将认证码存入SESSION
135 request.getSession ().setAttribute ("getImg", sRand);
136
137 // 图象生效
138 g.dispose ();
139
140 // 输出图象到页面
141 ImageIO.write (image, "PNG", response.getOutputStream ());
142 }
143 }
144
