最近在家閒來無事，看了幾天的書，頭有點大。手癢寫寫代碼。
1.目的
隨機產生驗證碼。用C#GDI+繪圖完成，由於我現在只會簡單的winform程序，完成後在winform上顯示。
2.思路
隨機在一定的字符中挑選幾個，然後將每個字符的各個屬性（字體，大小，顏色）隨機生成，接着畫出來就可以了。
3.實現
3.1定義變量
這裏的產生的字符數目和字體及顏色都可以自己添加。小建議：驗證碼所含的字符最好不要有歧義的，例如數字1和字母l。
char[] data = new char[6]; //用來裝產生的隨機字符，大小可變
//字符顏色、字體等變化範圍
string[] myFont = { "Times New Roman", "MS Mincho", "Book Antiqua", "Gungsuh", "PMingLiU", "Impact", "微軟雅黑", "宋體" };
Color[] myColor = { Color.Black, Color.Red, Color.Blue, Color.Green, Color.Orange, Color.Brown, Color.Brown, Color.DarkBlue };
char[] myChar = { '2', '3', '4', '5', '6', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'J',
'K', 'L', 'M', 'N', 'P', 'R', 'S', 'T', 'W', 'X', 'Y','Z','a','b','c','d','e',
'f','g','h','j','k','m','n','p','r','s','t','w','x','y','z'};3.2定義畫布和bitmap等變量
背景爲白色。從myBitmap創建畫布。
Graphics g = this.CreateGraphics();
Bitmap myBitmap=new Bitmap(200,100);
g = Graphics.FromImage(myBitmap);
g.Clear(Color.White);接下來是定義隨機變量Random。
Random r = new Random(DateTime.Now.Second);3.3畫
驗證碼還含有一些其他的線和點，來混淆視線。
//畫燥線
for (int i = 0; i < 10; i++)
{
int x1 = r.Next(200);
int y1 = r.Next(100);
int x2 = r.Next(200);
int y2 = r.Next(100);
Color clr = myColor[r.Next(myColor.Length)];
g.DrawLine(new Pen(clr), new Point(x1, y1), new Point(x2, y2));
}
//畫字符
for (int i = 0; i < data.Length; i++)
data[i] = (char)myChar[r.Next(myChar.Length)];
for (int i = 0; i < data.Length; i++)
{
Font tempFont = new Font(myFont[r.Next(myFont.Length)], 18);
g.DrawString(data[i].ToString(), tempFont,
new SolidBrush(myColor[r.Next(myColor.Length)]), (float)i * 20 + 40, (float)40);
}
//畫燥點
for (int i = 0; i < 100; i++)
{
int x = r.Next(myBitmap.Width);
int y = r.Next(myBitmap.Height);
Color tempColor = myColor[r.Next(myColor.Length)];
myBitmap.SetPixel(x, y, tempColor);
}；3.4顯示和保存
畫完成了，但這是並沒有顯示出來，這時只畫在myBitmap中，爲了將他顯示出來，定義另一個畫布。
Graphics thisGr;
thisGr = this.CreateGraphics();
thisGr.DrawImage(myBitmap, new Point(90, 35));這就完成了。
在退出前，不要忘記釋放資源。
4.不足
產生的驗證碼不美觀，且驗證碼中的字符沒有傾斜的效果。
5.代碼
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.IO;
using System.Drawing.Imaging;
namespace Ch53_隨機產生驗證碼
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
thisGr = this.CreateGraphics();
}
char[] data = new char[6]; //用來裝產生的隨機字符，大小可變
//字符顏色、字體等變化範圍
string[] myFont = { "Times New Roman", "MS Mincho", "Book Antiqua", "Gungsuh", "PMingLiU", "Impact", "微軟雅黑", "宋體" };
Color[] myColor = { Color.Black, Color.Red, Color.Blue, Color.Green, Color.Orange, Color.Brown, Color.Brown, Color.DarkBlue };
char[] myChar = { '2', '3', '4', '5', '6', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'J',
'K', 'L', 'M', 'N', 'P', 'R', 'S', 'T', 'W', 'X', 'Y','Z','a','b','c','d','e',
'f','g','h','j','k','m','n','p','r','s','t','w','x','y','z'};
Graphics thisGr;
private void btnSet_Click(object sender, EventArgs e)
{
Graphics g = this.CreateGraphics();
Bitmap myBitmap=new Bitmap(200,100);
g = Graphics.FromImage(myBitmap);
g.Clear(Color.White);
Random r = new Random(DateTime.Now.Second);
//畫燥線
for (int i = 0; i < 10; i++)
{
int x1 = r.Next(200);
int y1 = r.Next(100);
int x2 = r.Next(200);
int y2 = r.Next(100);
Color clr = myColor[r.Next(myColor.Length)];
g.DrawLine(new Pen(clr), new Point(x1, y1), new Point(x2, y2));
}
//畫字符
for (int i = 0; i < data.Length; i++)
data[i] = (char)myChar[r.Next(myChar.Length)];
for (int i = 0; i < data.Length; i++)
{
Font tempFont = new Font(myFont[r.Next(myFont.Length)], 18);
g.DrawString(data[i].ToString(), tempFont,
new SolidBrush(myColor[r.Next(myColor.Length)]), (float)i * 20 + 40, (float)40);
}
//畫燥點
for (int i = 0; i < 100; i++)
{
int x = r.Next(myBitmap.Width);
int y = r.Next(myBitmap.Height);
Color tempColor = myColor[r.Next(myColor.Length)];
myBitmap.SetPixel(x, y, tempColor);
}
myBitmap.Save("c:\\photo.gif");
thisGr.DrawImage(myBitmap, new Point(90, 35));
myBitmap.Dispose();
g.Dispose();
}
private void Form1_FormClosing(object sender, FormClosingEventArgs e)
{
thisGr.Dispose();
}
}
}