ASP.NET2.0图片格式转换【月儿原创】
?ASP.NET2.0圖片格式轉(zhuǎn)換
作者：清清月兒
主頁：http://blog.csdn.net/21aspnet/?????????? 時間：2007.4.20
說明：本文實現(xiàn)了
圖片格式隨意轉(zhuǎn)換（下拉框選擇）；
點擊FileUpload立即顯示圖片（Js實現(xiàn)）的技巧；
?
第一步：打開頁面
第二步：選擇一副Jpg格式的圖片
第三步：轉(zhuǎn)換為GIF格式，明顯看出圖片畫質(zhì)降低。
后臺代碼：
using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.IO;
using System.Drawing;
public partial class _Default : System.Web.UI.Page
{
??? protected void Page_Load(object sender, EventArgs e)
??? {
??? }
??? protected void Button1_Click(object sender, EventArgs e)
??? {
??????? string filepath = FileUpload1.PostedFile.FileName;
??????? string filename = filepath.Substring(filepath.LastIndexOf("//") + 1);
??????? string serverpath = Server.MapPath("images/") + System.DateTime.Now.ToString("yyy-MM-dd-hh-mm-ss") + Session.SessionID + filename;
??????? if (DropDownList1.SelectedValue == "GIF")
??????? {
??????????? ConvertImage(FileUpload1.PostedFile.FileName, System.Drawing.Imaging.ImageFormat.Gif, serverpath+".gif");
??????? }
??????? else if(DropDownList1.SelectedValue == "Jpeg")
??????? {
??????????? ConvertImage(FileUpload1.PostedFile.FileName, System.Drawing.Imaging.ImageFormat.Jpeg, serverpath + ".jpg");
??????? }
??????? else if(DropDownList1.SelectedValue == "Bmp")
??????? {
??????????? ConvertImage(FileUpload1.PostedFile.FileName, System.Drawing.Imaging.ImageFormat.Bmp, serverpath + ".bmp");
??????? }
??????? else
??????? {
??????? //清清月兒留給大家http://blog.csdn.net/21aspnet
??????? }
??? }
??? public void ConvertImage(string Filename, System.Drawing.Imaging.ImageFormat DesiredFormat, string NewFilename)
??? {
??????? try
??????? {
??????????? System.Drawing.Image imgFile = System.Drawing.Image.FromFile(Filename);
??????????? imgFile.Save(NewFilename, DesiredFormat);
??????????? Image1.ImageUrl = NewFilename;
??????????? Label1.Text = "轉(zhuǎn)換成功，生成"+NewFilename+"，如下所示。";
??????????? TextBox1.Text = "1";//開始為0，轉(zhuǎn)換后為1
??????? }
??????? catch (Exception ex)
??????? {
??????????? Response.Write(ex);
??????? }
??? }
}
?
前臺代碼：
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
??? <title>圖片格式轉(zhuǎn)換</title>
??? <script language="javascript">
???? function show_img()//實現(xiàn)選擇圖片后立即顯示給客戶
??????? {
???????
??????? if(document.all.TextBox1.value=="0"){//開始為0，轉(zhuǎn)換后為1
??????? document.all.Image1.src=document.all.FileUpload1.value;
??????? }
??????? else if(document.all.TextBox1.value=="1")
??????? {
??????? }
??????? }
??? </script>
</head>
<body>
??? <form id="form1" runat="server">
??? <div>
???????
??????? <table>
??????????? <tr>
??????????????? <td style="width: 124px">
??????????????????? <asp:FileUpload ID="FileUpload1" runat="server" οnmοuseοver="show_img()" Width="349px"/>
??????????????? </td>
??????????????? <td style="width: 100px">
??????????????????? 格式<asp:DropDownList ID="DropDownList1" runat="server">
??????????????????????? <asp:ListItem>GIF</asp:ListItem>
??????????????????????? <asp:ListItem>Jpeg</asp:ListItem>
??????????????????????? <asp:ListItem>Bmp</asp:ListItem>
??????????????????????? <asp:ListItem>Png</asp:ListItem>
??????????????????????? <asp:ListItem>Ico</asp:ListItem>
??????????????????? </asp:DropDownList>
??????????????? </td>
??????????????? <td style="width: 100px">
??????????????????? <asp:Button ID="Button1" runat="server" OnClick="Button1_Click" Text="轉(zhuǎn)換" /></td>
??????????????? <td style="width: 100px">
??????????????????? <asp:TextBox ID="TextBox1" runat="server">0</asp:TextBox>
??????????????????? </td>
??????????? </tr>
??????????? <tr>
??????????????? <td colspan="4">
??????????????????? <asp:Label ID="Label1" runat="server"></asp:Label></td>
??????????? </tr>
??????????? <tr>
??????????????? <td style="height: 26px;" colspan="4">
??????????????????? <asp:Image ID="Image1" runat="server" /></td>
??????????? </tr>
??????? </table>
???
??? </div>
??? </form>
</body>
</html>
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