创建vcode.jsp验证码的Java实现与步骤详解

此实现共分三个文件，即：CreatImage.java 生成图像流的类，提供用于生成图片流的方法；images.jsp 图片包装，用于将图片加入到response输出流中；login.jsp 调用前面的jsp，显示验证码。
CreatImage.java 类：
3 import java.awt.Color;
 4 import java.awt.Font;
 5 import java.awt.Graphics;
 6 import java.awt.Image;
 7 import java.awt.image.BufferedImage;
 8 import java.util.Random;
 9 
10 import javax.servlet.http.HttpServletRequest;
11 import javax.servlet.http.HttpServletResponse;
12 import javax.servlet.http.HttpSession;
13 
14 public class CreatImage{
15    
16     private static final long serialVersionUID = 1L;
17     Image image = null;
18     HttpServletRequest request = null;
19     HttpServletResponse response = null;
20     
21     public CreatImage(HttpServletRequest request, HttpServletResponse response){
22         this.request = request;
23         this.response = response;
24     }
25     
26     public Color getRandColor(int fc,int bc){//给定范围获得随机颜色
27         Random random = new Random();
28         if(fc>255) fc=255;
29         if(bc>255) bc=255;
30         int r=fc random.nextInt(bc-fc);

31         int g=fc random.nextInt(bc-fc);
32         int b=fc random.nextInt(bc-fc);
33         return new Color(r,g,b);
34     }
35     
36     public BufferedImage creatImage(){
37          int width=100, height=26;
38          //生成随机类
39          Random random = new Random();
40          BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
41          //获取图形上下文
42          Graphics g = image.getGraphics();
43          // 设定背景色
44          g.setColor(getRandColor(200,250));
45          g.fillRect(0, 0, width, height);
46          //设定字体
47          g.setFont(new Font("Times New Roman",Font.PLAIN,22));
48     
49          //画边框
50          //g.setColor(getRandColor(200,250));
51          //g.drawRect(0,0,width,height);
52     
53          // 随机产生155条干扰线，使图象中的认证码不易被其它程序探测到
54          g.setColor(getRandColor(160,200));
55          for (int i=0;i<155;i  ){
56            int x = random.nextInt(width);
57            int y = random.nextInt(height);
58            int xl = random.nextInt(12);
59            int yl = random.nextInt(12);
60            g.drawLine(x,y,x xl,y yl);