ASP.NET动态生成验证码

      从现在开始我会将我学习的东西一点一点的写到博客上与大家分享，一是我在写的过程中能更加熟练，二希望让刚开始学习asp.net的同学可以参考。

因为我本人也是刚刚接触asp.net还是个菜鸟，有错误之处还希望能留言，十分感谢！

动态生成验证码实例：

                        1. 首先在前台写好相应的代码：

                               <table><tr><td>

                               <img src ="CodeHandler.ashx" id ="image"/>

                                </td><td><asp:LinkButton runat = "server"  text="更换验证码！"</td></tr></table>  

                       2. 有了这些外海需要加上一些js代码，这样才能保证不会刷新整个页面

                                <script type="text/javascript>

                                      function changcode(){

                                                var src = CodeHandler.ashx?time= date();

                                                document.GetelementByid("image").src= src;

                                         }

                        3.在项目中添加一个一般处理程序

                                   

                          private static System.Random random = new Random();

                         public void ProcessRequest(HttpContext context)
                         {
                                  context.Response.ContentType = "Image/jpeg";

                                   //创建位图
                                  System.Drawing.Bitmap bitmap = new System.Drawing.Bitmap(100,50);

                                   using (System.Drawing.Graphics g = System.Drawing.Graphics.FromImage(bitmap))
                                  {

                                            //上颜色
                                              g.Clear(System.Drawing.Color.Beige);

                                              string CodeString = random.Next(1000, 10000).ToString();

                                              context.Session["Code"] = CodeString;

                                              //设置字体位置
                                              System.Drawing.StringFormat sf = new System.Drawing.StringFormat();

                                              sf.Alignment = System.Drawing.StringAlignment.Center;
                                              sf.LineAlignment = System.Drawing.StringAlignment.Center;

                                              g.DrawString(CodeString,
                                              new System.Drawing.Font("Arial",16),
                                              System.Drawing.Brushes.DarkKhaki,
                                              new System.Drawing.Rectangle(0,0,bitmap.Width,bitmap.Height),
                                              sf);

                                   }

                                   bitmap.Save(context.Response.OutputStream,System.Drawing.Imaging.ImageFormat.Jpeg);
                            }