asp.net中3种验证码示例(实现代码)(数字,数字字母混和,汉字)

<table>
<tr>
<td class="style1">
 (验证码测试)</td>
<td>
  <asp:label
id="label1" runat="server"></asp:label>
 
<asp:image id="image1" runat="server" height="22px" imageurl="~/validnums.aspx" width="58px" /> 
<asp:image id="image2" runat="server" height="22px" imageurl="~/getvalid.aspx" width="58px" /></td>
</tr> <tr>
<td class="style1">
 
</td>
<td>
  <asp:button id="button1" runat="server" text="登录" onclick="btnok_click" />
  
<asp:button id="button2" runat="server" text="取消" />
</td>
</tr>
</table>

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)
{
if (!page.ispostback)
{
string getnums = getvali();
label1.text = getnums;
}
}

/// <summary>
/// 随机生成4位数
/// </summary>
/// <returns>返回生成的随机数</returns>
public string getvali()
{
string strsvali = "0,1,2,3,4,5,6,7,8,9";
string[] valiarray = strsvali.split(',');
string returnnum = "";
int nums = -1;
random vrand = new random();
for (int n = 1; n < 5; n++)
{
if (nums != -1)
{
vrand = new random(n * nums * unchecked((int)datetime.now.ticks));
}
int t = vrand.next(10);
nums = t;
returnnum += valiarray[t];
}
session["valid"] = returnnum;
return returnnum;
}
protected void btnok_click(object sender, eventargs e)
{
if (session["valid"].tostring() == textbox3.text)
{
clientscript.registerstartupscript(this.gettype(),"ss","<script>alert('您已经成功通过登录验证！')</script>");
}
else
{
clientscript.registerstartupscript(this.gettype(), "ss", "<script>alert('您输入的验证码错误！')</script>");
}
}
}

using system;
using system.collections;
using system.configuration;
using system.data;
using system.linq;
using system.web;
using system.web.security;
using system.web.ui;
using system.web.ui.htmlcontrols;
using system.web.ui.webcontrols;
using system.web.ui.webcontrols.webparts;
using system.xml.linq;
using system.text;
using system.drawing;

public partial class getvalid : system.web.ui.page
{
protected void page_load(object sender, eventargs e)
{
if (!ispostback)
{
string validatenum = getvalids(); //成生4位随机字符串
createimage(validatenum); //将生成的随机字符串绘成图片
session["validnums"] = validatenum; //保存验证码
}
}
public static string getvalids()
{
//获取gb2312编码页（表）
encoding gb = encoding.getencoding("gb2312");

//调用函数产生4个随机中文汉字编码
object[] bytes = createregioncode(4);

//根据汉字编码的字节数组解码出中文汉字

string s = string.empty;
foreach (object byt in bytes)
{
string str1 = gb.getstring((byte[])convert.changetype(byt, typeof(byte[])));
s = s + str1;
}

//输出的控制台
return s;
}
public static object[] createregioncode(int strlength)
{
//定义一个字符串数组储存汉字编码的组成元素
string[] rbase = new string[16] { "0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "a", "b", "c", "d", "e", "f" };

random rnd = new random();

//定义一个object数组用来
object[] bytes = new object[strlength];
/*每循环一次产生一个含两个元素的十六进制字节数组，并将其放入bject数组中
每个汉字有四个区位码组成
区位码第1位和区位码第2位作为字节数组第一个元素
区位码第3位和区位码第4位作为字节数组第二个元素
*/
for (int i = 0; i < strlength; i++)
{
//区位码第1位
int r1 = rnd.next(11, 14);
string str_r1 = rbase[r1].trim();

//区位码第2位
rnd = new random(r1 * unchecked((int)datetime.now.ticks) + i);
//更换随机数发生器的种子避免产生重复值
int r2;
if (r1 == 13)
{
r2 = rnd.next(0, 8);
}
else
{
r2 = rnd.next(0, 16);
}
string str_r2 = rbase[r2].trim();

//区位码第3位
rnd = new random(r2 * unchecked((int)datetime.now.ticks) + i);
int r3 = rnd.next(10, 16);
string str_r3 = rbase[r3].trim();

//区位码第4位
rnd = new random(r3 * unchecked((int)datetime.now.ticks) + i);
int r4;
if (r3 == 10)
{
r4 = rnd.next(1, 16);
}
else if (r3 == 15)
{
r4 = rnd.next(0, 15);
}
else
{
r4 = rnd.next(0, 16);
}
string str_r4 = rbase[r4].trim();

//定义两个字节变量存储产生的随机汉字区位码
byte byte1 = convert.tobyte(str_r1 + str_r2, 16);
byte byte2 = convert.tobyte(str_r3 + str_r4, 16);
//将两个字节变量存储在字节数组中
byte[] str_r = new byte[] { byte1, byte2 };

//将产生的一个汉字的字节数组放入object数组中
bytes.setvalue(str_r, i);

}

return bytes;

}
//生成图片
private void createimage(string validatenum)
{
if (validatenum == null || validatenum.trim() == string.empty)
return;
//生成bitmap图像
system.drawing.bitmap image = new system.drawing.bitmap(validatenum.length * 12 + 10, 22);
graphics g = graphics.fromimage(image);

try
{
//生成随机生成器
random random = new random();

//清空图片背景色
g.clear(color.white);

//画图片的背景噪音线
for (int i = 0; i < 25; 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.coral), x1, y1, x2, y2);
}

font font = new system.drawing.font("arial", 8);
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(validatenum, font, brush, 2, 2);

//画图片的前景噪音点
for (int i = 0; i < 100; i++)
{
int x = random.next(image.width);
int y = random.next(image.height);
image.setpixel(x, y, color.fromargb(random.next()));
}

//画图片的边框线
g.drawrectangle(new pen(color.silver), 0, 0, image.width - 1, image.height - 1);

system.io.memorystream ms = new system.io.memorystream();
//将图像保存到指定的流
image.save(ms, system.drawing.imaging.imageformat.gif);
response.clearcontent();
response.contenttype = "image/gif";
response.binarywrite(ms.toarray());
}
finally
{
g.dispose();
image.dispose();
}
}
}

using system;
using system.collections;
using system.configuration;
using system.data;
using system.linq;
using system.web;
using system.web.security;
using system.web.ui;
using system.web.ui.htmlcontrols;
using system.web.ui.webcontrols;
using system.web.ui.webcontrols.webparts;
using system.xml.linq;
using system.drawing;

public partial class validnums : system.web.ui.page
{
protected void page_load(object sender, eventargs e)
{
if (!ispostback)
{
string validatenum = createrandomnum(4); //成生4位随机字符串
createimage(validatenum); //将生成的随机字符串绘成图片
session["validnums"] = validatenum; //保存验证码
}
}
//生成随机字符串
private string createrandomnum(int numcount)
{
string allchar = "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,w,x,y,z";
string[] allchararray = allchar.split(',');//拆分成数组
string randomnum = "";
int temp = -1;//记录上次随机数的数值，尽量避免产生几个相同的随机数
random rand = new random();
for (int i = 0; i < numcount; i++)
{
if (temp != -1)
{
rand = new random(i * temp * ((int)datetime.now.ticks));
}
int t = rand.next(35);
if (temp == t)
{
return createrandomnum(numcount);
}
temp = t;
randomnum += allchararray[t];
}
return randomnum;
}
//生成图片
private void createimage(string validatenum)
{
if (validatenum == null || validatenum.trim() == string.empty)
return;
//生成bitmap图像
system.drawing.bitmap image = new system.drawing.bitmap(validatenum.length * 12 + 10, 22);
graphics g = graphics.fromimage(image);

try
{
//生成随机生成器
random random = new random();

//清空图片背景色
g.clear(color.white);

//画图片的背景噪音线
for (int i = 0; i < 25; 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.coral), x1, y1, x2, y2);
}

font font = new system.drawing.font("arial", 12, (system.drawing.fontstyle.bold | system.drawing.fontstyle.italic));
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(validatenum, font, brush, 2, 2);

//画图片的前景噪音点
for (int i = 0; i < 100; i++)
{
int x = random.next(image.width);
int y = random.next(image.height);
image.setpixel(x, y, color.fromargb(random.next()));
}

//画图片的边框线
g.drawrectangle(new pen(color.silver), 0, 0, image.width - 1, image.height - 1);

system.io.memorystream ms = new system.io.memorystream();
//将图像保存到指定的流
image.save(ms, system.drawing.imaging.imageformat.gif);
response.clearcontent();
response.contenttype = "image/gif";
response.binarywrite(ms.toarray());
}
finally
{
g.dispose();
image.dispose();
}
}
}