[ASP.net WebForm] 圖形驗證碼(C#) + 前端驗證 - 懶人Code
先在網站專案中新增一個泛型處理常式 ValidateNumber.ashx
並加入以下的命名空間
using System;
using System.Web;
using System.Drawing;
using System.Web.SessionState;
完整產生圖形驗證碼(只有數字)的Code
<%@ WebHandler Language="C#" Class="ValidateNumber" %>
using System;
using System.Web;
using System.Drawing;
//如何於泛型處理常式 .ashx 中存取工作階段變數(Session Variable)
using System.Web.SessionState;
//http://www.limingchstudio.com/2009/05/ashx-session-variable.html
/*2011.10.5 Shadow 改寫,其他程式要判斷是否驗證成功,請比較Session["ValidateNumber"]的字串*/
public class ValidateNumber : IHttpHandler, IRequiresSessionState
{
public void ProcessRequest (HttpContext context) {
int NumCount = 5;//預設產生5位亂數
if(!string.IsNullOrEmpty(context.Request.QueryString["NumCount"]))
{//有指定產生幾位數
//字串轉數字,轉型成功的話儲存到 NumCount,不成功的話,NumCount會是0
Int32.TryParse(context.Request.QueryString["NumCount"].Replace("'","''"),out NumCount);
}
if(NumCount==0)NumCount=5;
//取得亂數
string str_ValidateCode = this.GetRandomNumberString(NumCount);
/*用於驗證的Session*/
context.Session["ValidateNumber"] = str_ValidateCode;
//取得圖片物件
System.Drawing.Image image = this.CreateCheckCodeImage(context,str_ValidateCode);
System.IO.MemoryStream ms = new System.IO.MemoryStream();
image.Save(ms , System.Drawing.Imaging.ImageFormat.Jpeg);
/*輸出圖片*/
context.Response.Clear();
context.Response.ContentType = "image/jpeg";
context.Response.BinaryWrite(ms.ToArray());
ms.Close();
}
#region 產生數字亂數
private string GetRandomNumberString(int int_NumberLength)
{
System.Text.StringBuilder str_Number = new System.Text.StringBuilder();//字串儲存器
Random rand = new Random(Guid.NewGuid().GetHashCode());//亂數物件
for(int i = 1 ;i<= int_NumberLength ;i++)
{
str_Number.Append( rand.Next(0,10).ToString() );//產生0~9的亂數
}
return str_Number.ToString();
}
#endregion
#region 產生圖片
private System.Drawing.Image CreateCheckCodeImage(HttpContext context,string checkCode)
{
System.Drawing.Bitmap image = new System.Drawing.Bitmap((checkCode.Length * 20), 40);//產生圖片,寬20*位數,高40像素
System.Drawing.Graphics g = Graphics.FromImage(image);
//生成隨機生成器
Random random =new Random(Guid.NewGuid().GetHashCode());
int int_Red =0;
int int_Green =0;
int int_Blue =0;
int_Red = random.Next(256);//產生0~255
int_Green = random.Next(256);//產生0~255
int_Blue = (int_Red + int_Green > 400 ? 0 : 400 - int_Red - int_Green);
int_Blue = (int_Blue > 255 ? 255: int_Blue);
//清空圖片背景色
g.Clear(Color.FromArgb(int_Red, int_Green, int_Blue));
//畫圖片的背景噪音線
for( int i = 0;i<= 24;i++)
{
int x1 = random.Next(image.Width);
int x2 = random.Next(image.Width);
int y1 = random.Next(image.Height);
int y2 = random.Next(image.Height);
g.DrawLine(new Pen(Color.Silver), x1, y1, x2, y2);
g.DrawEllipse(new Pen(Color.DarkViolet), new System.Drawing.Rectangle(x1, y1, x2, y2));
}
Font font = new System.Drawing.Font("Arial", 20, (System.Drawing.FontStyle.Bold));
System.Drawing.Drawing2D.LinearGradientBrush brush = new System.Drawing.Drawing2D.LinearGradientBrush(new Rectangle(0, 0, image.Width, image.Height), Color.Blue, Color.DarkRed, 1.2F, true);
g.DrawString(checkCode, font, brush, 2, 2);
for(int i = 0 ;i<= 99;i++)
{
//畫圖片的前景噪音點
int x = random.Next(image.Width);
int y = random.Next(image.Height);
image.SetPixel(x, y, Color.FromArgb(random.Next()));
}
//畫圖片的邊框線
g.DrawRectangle(new Pen(Color.Silver), 0, 0, image.Width - 1, image.Height - 1);
return image;
}
#endregion
/*實作 IHttpHandler介面的方法,不可刪除*/
public bool IsReusable
{
get
{
return false;
}
}
}
使用方式:
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title></title>
</head>
<body>
<form id="form1" runat="server">
<!--src連結到ValidateNumber.ashx即可-->
<img src="ValidateNumber.ashx" alt="驗證碼" />
</form>
</body>
</html>
如果要加上一個重新整理圖片(不postback)按鈕的話(參考來源:How to refresh the src of <img /> with jQuery?)
<form id="form1" runat="server">
<!--src連結到ValidateNumber.ashx即可-->
<img src="ValidateNumber.ashx" alt="驗證碼" name="imgCode" />
<input type="button" onclick="form1.imgCode.src='ValidateNumber.ashx?' + Math.random();" value="重新整理" />
</form>
接下來再做一個前端驗證,畫面大概這樣
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title></title>
<script src="js/jquery-1.4.1.min.js" type="text/javascript"></script>
<script type="text/javascript">
function isPassValidateCode()
{
}
</script>
</head>
<body>
<form id="form1" runat="server">
<!--src連結到ValidateNumber.ashx即可-->
<img src="ValidateNumber.ashx" alt="驗證碼" name="imgCode" />
<input type="button" onclick="form1.imgCode.src='ValidateNumber.ashx?' + Math.random();" value="重新整理" />
<hr />
<!--前端驗證結果訊息要放到span_result的innerHtml-->
<asp:TextBox ID="txt_input" runat="server" /><span id="span_result"></span>
<asp:Button Text="送出" ID="btn_submit" runat="server" OnClientClick="return isPassValidateCode();" />
</form>
</body>
</html>
再新增一個 readSessionValidateNumber.ashx專門做讀取Session[“ValidateNumber”]動作
<%@ WebHandler Language="C#" Class="readSessionValidateNumber" %>
using System;
using System.Web;
//如何於泛型處理常式 .ashx 中存取工作階段變數(Session Variable)
using System.Web.SessionState;
//參考:http://www.limingchstudio.com/2009/05/ashx-session-variable.html
public class readSessionValidateNumber : IHttpHandler, IRequiresSessionState
{
public void ProcessRequest (HttpContext context) {
context.Response.ContentType = "text/plain";
string ValidateNumber = (string)context.Session["ValidateNumber"];
context.Response.Write(ValidateNumber);
}
public bool IsReusable {
get {
return false;
}
}
}
然後用jQuery Ajax改寫function isPassValidateCode()
<script type="text/javascript">
function isPassValidateCode() {
var nowValidateNumber = jQuery.ajax({
url: "readSessionValidateNumber.ashx",
type: "post",
async: false,
data:{},
success: function (htmlVal) { }
}).responseText;
var userInput = jQuery("#<%= txt_input.ClientID%>").val();
var validateResult = ((nowValidateNumber == userInput) ? true : false);
if (validateResult == false) {
jQuery("#span_result").html("驗證碼輸入不正確");
}
//回傳true Or false
return validateResult;
}
</script>
另外在此支WebForm的Code-Behind寫下送出的Click事件,觀察看輸入的正不正確
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
public partial class _Default : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
}
protected void btn_submit_Click(object sender, EventArgs e)
{
Response.Write("剛剛輸入的是" + txt_input.Text + "<hr/>");
}
}
完整的 .aspx Code
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title></title>
<script src="js/jquery-1.4.1.min.js" type="text/javascript"></script>
<script type="text/javascript">
function isPassValidateCode() {
var nowValidateNumber = jQuery.ajax({
url: "readSessionValidateNumber.ashx",
type: "post",
async: false,
data:{},
success: function (htmlVal) { }
}).responseText;
var userInput = jQuery("#<%= txt_input.ClientID%>").val();
var validateResult = ((nowValidateNumber == userInput) ? true : false);
if (validateResult == false) {
jQuery("#span_result").html("驗證碼輸入不正確");
}
//回傳true Or false
return validateResult;
}
</script>
<!--驗證結果訊息為了美觀,多追加以下的css-->
<style type="text/css">
#span_result
{
color:Red;
font-size:12px;
}
</style>
</head>
<body>
<form id="form1" runat="server">
<!--src連結到ValidateNumber.ashx即可-->
<img src="ValidateNumber.ashx" alt="驗證碼" name="imgCode" />
<input type="button" onclick="form1.imgCode.src='ValidateNumber.ashx?' + Math.random();" value="重新整理" />
<hr />
<!--前端驗證結果訊息要放到span_result的innerHtml-->
<asp:TextBox ID="txt_input" runat="server" /><span id="span_result"></span>
<br />
<asp:Button Text="送出" ID="btn_submit" runat="server"
OnClientClick="return isPassValidateCode();" onclick="btn_submit_Click" />
</form>
</body>
</html>
執行畫面:
按下「重新整理」(網頁不會全部刷新)
未輸入或輸入錯誤的字串然後按送出
→
輸入正確的數字按送出的話
→
這程式應該還可以有改進空間,當jQuery Ajax取得Session中字串時,若Session逾時,應該要顯示逾時訊息給使用者
告訴使用者請再按重新整理,無奈我要下班了,所以這部份改天研究。
2011.10.5 18:50追加
當Session逾時,通知使用者的javascript code
<script type="text/javascript">
function isPassValidateCode() {
var nowValidateNumber = jQuery.ajax({
url: "readSessionValidateNumber.ashx",
type: "post",
async: false,
data:{},
success: function (htmlVal) { }
}).responseText;
if (nowValidateNumber == "" || nowValidateNumber == null) {
alert("驗證碼逾時,請重新整理");
return false;
}
var userInput = jQuery("#<%= txt_input.ClientID%>").val();
var validateResult = ((nowValidateNumber == userInput) ? true : false);
if (validateResult == false) {
jQuery("#span_result").html("驗證碼輸入不正確");
}
//回傳Ctrue Or false
return validateResult;
}
</script>
試了一下,當Session逾時,按了重新整理按鈕後,若成功送出postback時,圖片仍會和第一張一樣
但Session裡的字串早已不一樣,使用者就算輸入和圖片一樣的數字,仍然不會通過驗證
為了避免此Bug,javascript要再改寫:(↓全部完整的 .aspx)
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title></title>
<script src="js/jquery-1.4.1.min.js" type="text/javascript"></script>
<script type="text/javascript">
jQuery(document).ready(init);
function init() {
/*每次Dom載入完,確保圖片都不一樣*/
jQuery("img[name='imgCode']").attr("src", "ValidateNumber.ashx?" + Math.random());
}
function isPassValidateCode() {
var nowValidateNumber = jQuery.ajax({
url: "readSessionValidateNumber.ashx",
type: "post",
async: false,
data:{},
success: function (htmlVal) { }
}).responseText;
if (nowValidateNumber == "" || nowValidateNumber == null) {
alert("驗證碼逾時,請重新整理");
return false;
}
var userInput = jQuery("#<%= txt_input.ClientID%>").val();
var validateResult = ((nowValidateNumber == userInput) ? true : false);
if (validateResult == false) {
jQuery("#span_result").html("驗證碼輸入不正確");
}
//回傳true Or false
return validateResult;
}
</script>
<!--驗證結果訊息為了美觀,多追加以下的css-->
<style type="text/css">
#span_result
{
color:Red;
font-size:12px;
}
</style>
</head>
<body>
<form id="form1" runat="server">
<!--src連結到ValidateNumber.ashx即可-->
<img src="ValidateNumber.ashx" alt="驗證碼" name="imgCode" />
<input type="button" onclick="form1.imgCode.src='ValidateNumber.ashx?' + Math.random();" value="重新整理" />
<hr />
<!--前端驗證結果訊息要放到ispan_result的innerHtml-->
<asp:TextBox ID="txt_input" runat="server" /><span id="span_result"></span>
<br />
<asp:Button Text="送出" ID="btn_submit" runat="server"
OnClientClick="return isPassValidateCode();" onclick="btn_submit_Click" />
</form>
</body>
</html>
2011.11.25 公司ART人員發現的簡潔樣式
http://www.tipstricks.org/
(下方可以Download Sample Code)
2012.01.07 產生的驗證碼圖片不可以存成實體文件,否則會有Cache問題