1 using System; 
 2 using System.Collections; 
 3 using System.ComponentModel; 
 4 using System.Data; 
 5 using System.Web; 
 6 using System.Web.SessionState; 
 7 using System.Web.UI; 
 8 using System.Web.UI.WebControls; 
 9 using System.Web.UI.HtmlControls; 
 10 using System.Drawing; 
 11 using System.Drawing.Imaging; 
 12 using System.Drawing.Text; 
 13 /**///// <summary> 
 14 /// 页面验证码程序 
 15 /// 使用：在页面中加入HTML代码 <img src="VerifyCode.aspx"> 
 16 ///</summary>
 17 public partial class VerifyCode : System.Web.UI.Page 
 18 { 
 19     static string[] FontItems = new string[] 
 20     { 
 21         "Arial", 
 22         "Helvetica", 
 23         "Geneva", 
 24         "sans-serif", 
 25         "Verdana" 
 26     }; 
 27     static Brush[] BrushItems = new Brush[] 
 28     { 
 29         Brushes.OliveDrab, 
 30         Brushes.ForestGreen, 
 31         Brushes.DarkCyan, 
 32         Brushes.LightSlateGray, 
 33         Brushes.RoyalBlue, 
 34         Brushes.SlateBlue, 
 35         Brushes.DarkViolet, 
 36         Brushes.MediumVioletRed, 
 37         Brushes.IndianRed, 
 38         Brushes.Firebrick, 
 39         Brushes.Chocolate, 
 40         Brushes.Peru, 
 41         Brushes.Goldenrod 
 42         }; 
 43     static string[] BrushName = new string[] 
 44     { 
 45         "OliveDrab", 
 46         "ForestGreen", 
 47         "DarkCyan", 
 48         "LightSlateGray", 
 49         "RoyalBlue", 
 50         "SlateBlue", 
 51         "DarkViolet", 
 52         "MediumVioletRed", 
 53         "IndianRed", 
 54         "Firebrick", 
 55         "Chocolate", 
 56         "Peru", 
 57         "Goldenrod" 
 58     }; 
 59     private static Color BackColor = Color.White; 
 60     private static Pen BorderColor = Pens.DarkGray; 
 61     private static int Width = 50; 
 62     private static int Height = 20; 
 63     private Random _random; 
 64     private string _code; 
 65     private int _brushNameIndex; 
 66     override protected void OnInit(EventArgs e) 
 67     { 
 68         // 
 69 // CODEGEN: This call is required by the ASP.NET Web Form Designer. 
 70 // 
 71 //InitializeComponent(); 
 72 //base.OnInit(e); 
 73     } 
 74     /**//**//**////<summary> 
 75 /// Required method for Designer support - do not modify 
 76 /// the contents of this method with the code editor. 
 77 ///</summary>
 78     private void InitializeComponent() 
 79     { 
 80         //this.Load += new System.EventHandler(this.Page_Load); 
 81     } 
 82     /**////<summary> 
 83 /// 
 84 ///</summary> 
 85 ///<param name="sender"></param> 
 86 ///<param name="e"></param>
 87     public void Page_Load(object sender, System.EventArgs e) 
 88     { 
 89         if (!IsPostBack) 
 90         { 
 91             // 
 92 // TODO : initialize 
 93 //
 94             this._random = new Random(); 
 95             this._code = GetRandomCode(); 
 96             // 
 97 // TODO : use Session["code"] save the VerifyCode 
 98 //
 99             Session["code"] = this._code; 
100             // 
101 // TODO : output Image 
102 //
103             this.SetPageNoCache(); 
104             this.OnPaint(); 
105         } 
106     } 
107     /**//**//**////<summary> 
108 /// 设置页面不被缓存 
109 ///</summary>
110     private void SetPageNoCache() 
111     { 
112         Response.Buffer = true; 
113         Response.ExpiresAbsolute = System.DateTime.Now.AddSeconds(-1); 
114         Response.Expires = 0; 
115         Response.CacheControl = "no-cache"; 
116         Response.AppendHeader("Pragma","No-Cache"); 
117     } 
118     /**//**//**////<summary> 
119 /// 取得一个 4 位的随机码 
120 ///</summary> 
121 ///<returns></returns>
122     private string GetRandomCode() 
123     { 
124         return Guid.NewGuid().ToString().Substring(0, 4); 
125     } 
126     /**//**//**////<summary> 
127 /// 随机取一个字体 
128 ///</summary> 
129 ///<returns></returns>
130     private Font GetFont() 
131     { 
132         int fontIndex = _random.Next(0, FontItems.Length); 
133         FontStyle fontStyle = GetFontStyle(_random.Next(0, 2)); 
134         return new Font(FontItems[fontIndex], 12, fontStyle); 
135     } 
136     /**//**//**////<summary> 
137 /// 取一个字体的样式 
138 ///</summary> 
139 ///<param name="index"></param> 
140 ///<returns></returns>
141     private FontStyle GetFontStyle(int index) 
142     { 
143         switch (index) 
144         { 
145             case 0: 
146             return FontStyle.Bold; 
147             case 1: 
148             return FontStyle.Italic; 
149             default: 
150             return FontStyle.Regular; 
151         } 
152     } 
153     /**//**//**////<summary> 
154 /// 随机取一个笔刷 
155 ///</summary> 
156 ///<returns></returns>
157     private Brush GetBrush() 
158     { 
159         int brushIndex = _random.Next(0, BrushItems.Length); 
160         _brushNameIndex = brushIndex; 
161         return BrushItems[brushIndex]; 
162     } 
163     /**//**//**////<summary> 
164 /// 绘画事件 
165 ///</summary>
166     private void OnPaint() 
167     { 
168         Bitmap objBitmap = null; 
169         Graphics g = null; 
170         try 
171         { 
172             objBitmap = new Bitmap(Width, Height); 
173             g = Graphics.FromImage(objBitmap); 
174             Paint_Background(g); 
175             Paint_Text(g); 
176             Paint_TextStain(objBitmap); 
177             Paint_Border(g); 
178             objBitmap.Save(Response.OutputStream, ImageFormat.Gif); 
179             Response.ContentType = "image/gif"; 
180         } 
181         catch{} 
182         finally 
183         { 
184             if (null != objBitmap) 
185                 objBitmap.Dispose(); 
186             if (null != g) 
187                 g.Dispose(); 
188         } 
189     } 
190     /**//**//**////<summary> 
191 /// 绘画背景颜色 
192 ///</summary> 
193 ///<param name="g"></param>
194     private void Paint_Background(Graphics g) 
195     { 
196         g.Clear(BackColor); 
197     } 
198     /**//**//**////<summary> 
199 /// 绘画边框 
200 ///</summary> 
201 ///<param name="g"></param>
202     private void Paint_Border(Graphics g) 
203     { 
204         g.DrawRectangle(BorderColor, 0, 0, Width - 1, Height - 1); 
205     } 
206     /**//**//**////<summary> 
207 /// 绘画文字 
208 ///</summary> 
209 ///<param name="g"></param>
210     private void Paint_Text(Graphics g) 
211     { 
212         g.DrawString(_code, GetFont(), GetBrush(), 3, 1); 
213     } 
214     /**//**//**////<summary> 
215 /// 绘画文字噪音点 
216 ///</summary> 
217 ///<param name="g"></param>
218     private void Paint_TextStain(Bitmap b) 
219     { 
220         for (int n=0; n<30; n++) 
221         { 
222             int x = _random.Next(Width); 
223             int y = _random.Next(Height); 
224             b.SetPixel(x, y, Color.FromName(BrushName[_brushNameIndex])); 
225         } 
226     } 
227 }