1 protected void page_load(object sender, eventargs e)
2     {
3         string tmp = rndnum(4);
4         httpcookie a = new httpcookie("imagev", tmp);
5         response.cookies.add(a);
6         this.validatecode(tmp);
7     }
8     private void validatecode(string vnum)
9     {
10         bitmap img = null;
11         graphics g = null;
12         memorystream ms = null;
1314         int gheight = vnum.length * 12;
15         img = new bitmap(gheight, 25);
16         g = graphics.fromimage(img);
17         //背景颜色18         g.clear(color.lightsteelblue);
19         //文字字体20         font f = new font("arial black", 10);
21         //文字颜色22         solidbrush s = new solidbrush(color.royalblue);
23         g.drawstring(vnum, f, s, 3, 3);
24         ms = new memorystream();
25         img.save(ms, imageformat.jpeg);
26         response.clearcontent();
27         response.contenttype = "images/jpeg";
28         response.binarywrite(ms.toarray());
29         g.dispose();
30         img.dispose();
31         response.end();
32     }
3334     private string rndnum(int vcodenum)
35     {
36         string vchar = "0,1,2,3,4,5,6,7,8,9,a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p" +37         ",q,r,s,t,u,v,w,x,y,z";
38         string[] vcarray = vchar.split(new char[] { ',' });
39         string vnum = "";
40         int temp = -1;
4142         random rand = new random();
4344         for (int i = 1; i < vcodenum + 1; i++)
45         {
46             if (temp != -1)
47             {
48                 rand = new random(i * temp * unchecked((int)datetime.now.ticks));
49             }
5051             int t = rand.next(35);
52             if (temp != -1 && temp == t)
53             {
54                 return rndnum(vcodenum);
55             }
56             temp = t;
57             vnum += vcarray[t];
58         }
59         return vnum;
60     }