代码如下,可以实现后台验证,也就是说,在提交事件里通过 Session["Code"]验证。可如何在客户端验证,如果验证码不正确干脆提交不了呢?
public partial class ValidateCode : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
string strKey = "";
byte[] data = this.GenerateVerifyImage(5, ref strKey);
Response.OutputStream.Write(data, 0, data.Length);
Session["Code"] = strKey;
} public byte[] GenerateVerifyImage(int nLen, ref string strKey)
{
int nBmpWidth = 25 * nLen + 5;
int nBmpHeight = 36;
System.Drawing.Bitmap bmp = new System.Drawing.Bitmap(nBmpWidth, nBmpHeight); // 1. 生成随机背景颜色
int nRed, nGreen, nBlue; // 背景的三元色
System.Random rd = new Random((int)System.DateTime.Now.Ticks);
nRed = 255;
nGreen = 255;
nBlue = 255; // 2. 填充位图背景
System.Drawing.Graphics graph = System.Drawing.Graphics.FromImage(bmp);
graph.FillRectangle(new SolidBrush(System.Drawing.Color.FromArgb(nRed, nGreen, nBlue))
, 0
, 0
, nBmpWidth
, nBmpHeight);
// 3. 绘制干扰线条,采用比背景略深一些的颜色
int nLines = 3;
System.Drawing.Pen pen = new System.Drawing.Pen(System.Drawing.Color.FromArgb(nRed - 17, nGreen - 17, nBlue - 17), 2);
for (int a = 0; a < nLines; a++)
{
int x1 = rd.Next() % nBmpWidth;
int y1 = rd.Next() % nBmpHeight;
int x2 = rd.Next() % nBmpWidth;
int y2 = rd.Next() % nBmpHeight;
graph.DrawLine(pen, x1, y1, x2, y2);
} // 采用的字符集,可以随即拓展,并可以控制字符出现的几率
string strCode = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"; // 4. 循环取得字符,并绘制
string strResult = "";
for (int i = 0; i < nLen; i++)
{
int x = (i * 22 + rd.Next(3));
int y = rd.Next(4) + 1; // 确定字体
System.Drawing.Font font = new System.Drawing.Font("Courier New",
24 + rd.Next() % 4,
System.Drawing.FontStyle.Bold);
char c = strCode[rd.Next(strCode.Length)]; // 随机获取字符
strResult += c.ToString(); // 绘制字符
graph.DrawString(c.ToString(),
font,
new SolidBrush(System.Drawing.Color.FromArgb(0, 128, 180)),
x,
y);
} // 5. 输出字节流
System.IO.MemoryStream bstream = new System.IO.MemoryStream();
bmp.Save(bstream, System.Drawing.Imaging.ImageFormat.Jpeg);
bmp.Dispose();
graph.Dispose();
Session["Code"] = strKey = strResult;
byte[] byteReturn = bstream.ToArray();
bstream.Close(); return byteReturn;
}
}asp.netstringbytesession
public partial class ValidateCode : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
string strKey = "";
byte[] data = this.GenerateVerifyImage(5, ref strKey);
Response.OutputStream.Write(data, 0, data.Length);
Session["Code"] = strKey;
} public byte[] GenerateVerifyImage(int nLen, ref string strKey)
{
int nBmpWidth = 25 * nLen + 5;
int nBmpHeight = 36;
System.Drawing.Bitmap bmp = new System.Drawing.Bitmap(nBmpWidth, nBmpHeight); // 1. 生成随机背景颜色
int nRed, nGreen, nBlue; // 背景的三元色
System.Random rd = new Random((int)System.DateTime.Now.Ticks);
nRed = 255;
nGreen = 255;
nBlue = 255; // 2. 填充位图背景
System.Drawing.Graphics graph = System.Drawing.Graphics.FromImage(bmp);
graph.FillRectangle(new SolidBrush(System.Drawing.Color.FromArgb(nRed, nGreen, nBlue))
, 0
, 0
, nBmpWidth
, nBmpHeight);
// 3. 绘制干扰线条,采用比背景略深一些的颜色
int nLines = 3;
System.Drawing.Pen pen = new System.Drawing.Pen(System.Drawing.Color.FromArgb(nRed - 17, nGreen - 17, nBlue - 17), 2);
for (int a = 0; a < nLines; a++)
{
int x1 = rd.Next() % nBmpWidth;
int y1 = rd.Next() % nBmpHeight;
int x2 = rd.Next() % nBmpWidth;
int y2 = rd.Next() % nBmpHeight;
graph.DrawLine(pen, x1, y1, x2, y2);
} // 采用的字符集,可以随即拓展,并可以控制字符出现的几率
string strCode = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"; // 4. 循环取得字符,并绘制
string strResult = "";
for (int i = 0; i < nLen; i++)
{
int x = (i * 22 + rd.Next(3));
int y = rd.Next(4) + 1; // 确定字体
System.Drawing.Font font = new System.Drawing.Font("Courier New",
24 + rd.Next() % 4,
System.Drawing.FontStyle.Bold);
char c = strCode[rd.Next(strCode.Length)]; // 随机获取字符
strResult += c.ToString(); // 绘制字符
graph.DrawString(c.ToString(),
font,
new SolidBrush(System.Drawing.Color.FromArgb(0, 128, 180)),
x,
y);
} // 5. 输出字节流
System.IO.MemoryStream bstream = new System.IO.MemoryStream();
bmp.Save(bstream, System.Drawing.Imaging.ImageFormat.Jpeg);
bmp.Dispose();
graph.Dispose();
Session["Code"] = strKey = strResult;
byte[] byteReturn = bstream.ToArray();
bstream.Close(); return byteReturn;
}
}asp.netstringbytesession
所以你想要进行验证码验证则必须通过服务端
用CustomValidator:自定义验证控件 轻松搞定。
CustomValidator控件允许用户自定义验证,可以在服务器端验证,可以在客户端验证,也可以在客户端和服务端同时验证下面的例子是验证一个数能否被2整除1. 服务器端验证
在验证的时候会用到IsValid这个属性,根据IsValid的值(true/false)来判断是否通过页面验证。a. 拖放控件TextBox用于输入值;Button用于测试验证状态,IsValid为true触发Click事件;CustomValidator控制要验证的对象和验证事件等。b. 设置CustomValidator的属性这里设置ErrorMessage为Not an even number!,ControlToValidate为Text1c. 编写CustomValidator的ServerValidation事件
protected void CustomValidator1_ServerValidate(object source, ServerValidateEventArgs args)
{try
{
int num = int.Parse(args.Value);
args.IsValid = ((num%2)==0);
}
catch (Exception ex)
{
args.IsValid = false;
}
}
d. 编写Button的Click事件
protected void Button2_Click(object sender, EventArgs e)
{
if (Page.IsValid)
{
Response.Redirect("gouWuChe.aspx");
}
else
{
//提示
}}
2. 客户端验证使用javascript function验证,并用设置ClientValidationFunction为javascript 验证函数(function)a. Javascript 函数<script language="javascript">function ValidateNumber(source,args){if(args.Value%2==0){args.IsValid=true;}else{args.IsValid=false;}}</script>b. 设置CustomValidator的属性这里设置ErrorMessage为请输入能被2整除的数,ControlToValidate为TextBox1, ClientValidationFunction为ValidateNumberc. 编写Button的Click事件
protected void Button2_Click(object sender, EventArgs e)
{
if (Page.IsValid)
{
Response.Redirect("gouWuChe.aspx");
}
else
{
//提示
}}3. 客户端和服务端同时验证将上面的两部分代码合并可以了
但是像验证验证码这样的需求完全没必要这么做一般含验证码登录之类的可以这么做:
当用户输入账号密码验证码后
用js判断输入的长度是否符合,有没有非法字符
然后用ajax向服务器端发送账号密码验证码
在服务器端首先判断你的验证码字符串和session[验证码]是否一样
如果不一样就直接返回false了 提示验证码错误
如果通过了验证码的验证再去验证你的账号密码就ok了