ASP.NET下生产图片验证码

2024-07-10 13:10:53

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来源：转载

供稿：网友

后台文件:

1using system;
2using system.data;
3using system.configuration;
4using system.collections;
5using system.drawing;
6using system.web;
7using system.web.security;
8using system.web.ui;
9using system.web.ui.webcontrols;
10using system.web.ui.webcontrols.webparts;
11using system.web.ui.htmlcontrols;
12
13public partial class default2 : system.web.ui.page
14{
15    protected void page_load(object sender, eventargs e)
16    {
17        if(!this.ispostback)
18        {
19            this.genimg(this.gencode(4));
20        }
21
22    }
23    //产生随机字符串
24    private string gencode(int num)
25    {
26        string[] source={"0","1","2","3","4","5","6","7","8","9",
27                            "a","b","c","d","e","f","g","h","i","j","k","l","m","n",
28                            "o","p","q","r","s","t","u","v","w","x","y","z"};
29        string code="";
30        random rd=new random();
31        for(int i=0;i < num;i++)
32        {
33            code += source[rd.next(0,source.length)];
34        }
35        return code;
36    }
37
38        //生成图片
39    private void genimg(string code)
40    {
41        bitmap mypalette = new bitmap(60, 20);//定义一个画板
42
43        graphics gh = graphics.fromimage(mypalette);//在画板上定义绘图的实例
44
45        rectangle rc = new rectangle(0, 0, 60, 20);//定义一个矩形
46
47        gh.fillrectangle(new solidbrush(color.blue), rc);//填充矩形
48        gh.drawstring(code, new font("宋体", 16), new solidbrush(color.white), rc);//在矩形内画出字符串
49
50        mypalette.save(response.outputstream, system.drawing.imaging.imageformat.jpeg);//将图片显示出来
51
52        session["validatecode"] = code;//将字符串保存到session中，以便需要时进行验证
53
54        gh.dispose();
55        mypalette.dispose();
56    }
57
58}