雕虫小技--自定义“验证码”控件
“验证码”在登录的时候，经常用到，如果把“她”封装成控件，是不是很爽呢？但是，我一般不喜欢封装得太厉害的“她”，因为什么都看不到，亦或看起来比较朦胧:)
切入点
利用IHttpHandler接口，动态生成验证码
图一（直接看效果吧）
看代码吧
步骤一(新建一类库)
Code
using System;
using System.Collections.Generic;
using System.Text;
using System.Web;
using System.Web.SessionState;
using System.Web.UI;
using System.Drawing;
namespace ControlValidater
{
public class CValidater:IHttpHandler,IRequiresSessionState
{
HttpResponse response = null;
HttpSessionState sessionState = null;
public void ProcessRequest(HttpContext context)
{
response = context.Response;
sessionState = context.Session;
this.GenImg(this.GenCode(4));
}
bool System.Web.IHttpHandler.IsReusable
{
get { return true; }
}
//产生随机字符串
private string GenCode(int num)
{
string[] source ={"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","Q","R","S","T","U","V","W","X","Y","Z"};
string code = "";
Random rd = new Random();
for (int i = 0; i < num; i++)
{
code += source[rd.Next(0, source.Length)];
}
return code;
}
//生成图片
private void GenImg(string code)
{
Bitmap myPalette = new Bitmap(60, 20);//定义一个画板
Graphics gh = Graphics.FromImage(myPalette);//在画板上定义绘图的实例
Rectangle rc = new Rectangle(0, 0, 60, 20);//定义一个矩形
gh.FillRectangle(new SolidBrush(Color.Silver), rc);//填充矩形
gh.DrawString(code, new Font("宋体", 16), new SolidBrush(Color.Gray), rc);//在矩形内画出字符串
myPalette.Save(response.OutputStream, System.Drawing.Imaging.ImageFormat.Jpeg);//将图片显示出来
sessionState["ValidateCode"] = code;//将字符串保存到Session中，以便需要时进行验证
gh.Dispose();
myPalette.Dispose();
}
}
}
步骤二(使用方法)
直接引用编译后的dll文件
在web.config的web节点,加入<httpHandlers>元素,
例如
Code
<httpHandlers>
<add path="CValidater.aspx" verb="*" type="ControlValidater.CValidater" />
</httpHandlers>
当然,如果直接把类库作为一个普通类,放在使用的Website的App_Data目录的话,就不需要配置了:)
步骤三(使用方法)
在需要使用验证码的页面,扔一个image标记,然后把他的url指向"类名.aspx"
例如
Code
<asp:Image ID="Image1" runat="server" ImageUrl="~/CValidater.aspx"/>
到此配置完成,是不是很简单呢:)
哎...
还是把最后一个步骤代码贴出来吧.
Code
protected void Button1_Click(object sender, EventArgs e)
{
string strIn = this.TextBox1.Text;
string strSess = Session["ValidateCode"].ToString();
if (strIn == strSess)
Button1.Text = "ok";
else
Button1.Text = "error";
}
需要注意的几个地方:)
一,记得要实现IRequiresSessionState接口,虽然她只是一个标记,没有她,Session状态无法使用.
二,HttpSessionState的对象是通过上下文获得的.
三,配制config的时候,不要忘记path="CValidater.aspx",如果path="*.aspx",那你所有的页面都将被CValidater处理,这不是我们所要的.