Image upload, image watermark, Verification code production

File Upload:

　　Controls used: FileUpload

When using the idea:

1, determine whether the user selected files

Fileupload.filename Gets the selected file name, determines the length, if the length is greater than 0 means that the file has been selected

JS End: Gets the control by ID and then the value of the control gets the selected file name

2. Save the file to the server

Fileupload.saveas ("absolute path");

3. Get absolute path

Write a relative path first: "Uploads/abc.txt", for example

Then map the path to absolute path: Server.MapPath ("Uploads/abc.txt");

4, keep the original file type and file name

The relative path is changed to "uploads/" + fileupload1.filename;

5, prevent the file name overlay problem

"uploads/" + request.cookies["user"]. Value + DateTime.Now.ToString ("yyyymmddhhmmssms") + fileupload1.filename;

That is, in front of the file name stitching on the login user name and operation time, accurate to milliseconds

6. Restrict user-selectable file types

Add Property accept= ". Jpg,.png,.jpeg,.txt" to the control

However, in the Open dialog box, you can still select all the files, only through the JS side to limit:

document.getElementById ("Button1"). onclick = function () {        var fileName = document.getElementById ("FileUpload1"). value;                var name = Filename.substr (filename.length-4, 4);        var name1 = Filename.substr (filename.length-5, 5);        if (name! = ". jpg" && name! = ". png" && name! = ". txt" && name1! = ". jpeg")        {            alert ("Please select the correct The file! You're looking for something, huh? ");            return false;        }     };

Image plus watermark:

<%@ Page language="C #"autoeventwireup="true"codefile="Shuiyin.aspx.cs"inherits="Shuiyin"%><! DOCTYPE html>"http://www.w3.org/1999/xhtml">"Server"> <meta http-equiv="Content-type"Content="text/html; Charset=utf-8"/> <title></title>"Form1"runat="Server"> <div> <asp:fileupload id="FileUpload1"runat="Server"/><asp:button id="Button1"runat="Server"text="Button"/> <asp:image id="Image1"runat="Server"/> </div> </form></body>
usingSystem;usingSystem.Collections.Generic;usingSystem.Linq;usingsystem.web;usingSystem.Web.UI;usingSystem.Web.UI.WebControls;//Be sure to add this reference!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!usingSystem.Drawing; Public Partial classshuiyin:system.web.ui.page{protected voidPage_Load (Objectsender, EventArgs e) {Button1.Click+=button1_click; }    voidButton1_Click (Objectsender, EventArgs e) {        //get the picture you want to uploadSystem.Drawing.Image img =System.Drawing.Image.FromStream (fileupload1.filecontent); //Add Watermark//Turn The get picture into a GDI drawing surface and start drawingGraphics g =graphics.fromimage (IMG); //corresponding (watermark content, watermark font, watermark color, watermark location)g.DrawString ("ha ha haha",NewFont ("Microsoft Ya-Black", -),NewSolidBrush (color.red),NewPointF (0,0)); //Save Picture//img refers to the folder name, followed by renaming the file to be watermarked        stringUL ="img/"+ DateTime.Now.ToString ("yyyymmddhhmmssms") +Fileupload1.filename; //save and generate an absolute pathimg.        Save (Server.MapPath (UL)); //show the effect and look at it.Image1.imageurl =ul; }}
Effect:
Image upload, image watermark, Verification code production