Asp.net開發之webform圖片浮水印和圖片驗證碼的實現方法_實用技巧

兩者都需要引入命名空間：using System.Drawing;

一、圖片浮水印

前台Photoshuiyin.aspx代碼：

<div><asp:FileUpload ID="FileUpload1" runat="server" /><asp:Button ID="Button1" runat="server" Text="上傳" /><br /><asp:Image ID="Image1" runat="server" /></div>

後台Photoshuiyin.aspx.cs代碼：

protected void Page_Load(object sender, EventArgs e){Button1.Click += Button1_Click;}void Button1_Click(object sender, EventArgs e){//1、製作畫布System.Drawing.Image img = System.Drawing.Image.FromStream(FileUpload1.FileContent);Graphics g = Graphics.FromImage(img);//浮水印樣式：畫什麼東西string a = "http://www.itnba.com";//字型、大小Font f = new Font("黑體", 30);//顏色Brush b = new SolidBrush(Color.Red);//0,0——開始畫浮水印的位置g.DrawString(a, f, b, 0, 0);//儲存路徑string path = "images/" + FileUpload1.FileName;img.Save(Server.MapPath(path));//在image控制項中展示Image1.ImageUrl = path;}

效果展示：

二、圖片驗證碼

前台Photoyanzhengma.aspx代碼：

<form id="form1" runat="server"><div>使用者名稱：<asp:TextBox ID="TextBox1" runat="server"></asp:TextBox><br />密碼：<asp:TextBox ID="TextBox2" runat="server"></asp:TextBox><br />驗證碼：<asp:TextBox ID="TextBox3" runat="server"></asp:TextBox><asp:Image ID="Image1" runat="server" ImageUrl="YZM.aspx" /><asp:Label ID="Label1" runat="server" Text="Label"></asp:Label><br /><asp:Button ID="Button1" runat="server" Text="Button" /></div></form></body></html><script type="text/javascript">var aaa = 1;document.getElementById("Image1").onclick = function () {this.setAttribute("src", "YZM.aspx?id=" + aaa);aaa++;};</script>

連結頁面“YZM.aspx”——無需前台代碼，後台代碼是：

protected void Page_Load(object sender, EventArgs e){Random r = new Random();string aaa = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890";//產生畫布Bitmap img = new Bitmap(80, 30);//畫布背景色泛性組合List<Color> Clist = new List<Color>();Clist.Add(Color.Yellow);Clist.Add(Color.Green);Clist.Add(Color.Blue);Clist.Add(Color.Aqua);Clist.Add(Color.Orange);Clist.Add(Color.Pink);Graphics g = Graphics.FromImage(img);g.FillRectangle(new SolidBrush(Clist[r.Next(0, Clist.Count)]), 0, 0, 80, 30);//隨機產生顯示的驗證碼組合string str = "";for (int i = 0; i < 4; i++){str += aaa.Substring(r.Next(0, aaa.Length), 1);}Session["YZM"] = str;Font f = new Font("黑體", 20);Brush b = new SolidBrush(Color.Red);//產生g.DrawString(str, f, b, 10, 0);//添加幹擾線for (int i = 0; i < r.Next(6, 20); i++){Brush bb = new SolidBrush(Clist[r.Next(0, Clist.Count)]);Pen p = new Pen(bb, 1);g.DrawLine(p, r.Next(0, 80), r.Next(0, 30), r.Next(0, 80), r.Next(0, 30));}//儲存完成img.Save(Response.OutputStream, System.Drawing.Imaging.ImageFormat.Jpeg);Response.End();}

效果展示：

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