ASP.NET2.0图片格式转换

来源：互联网发布：软件报价依据编辑：程序博客网时间：2024/05/21 11:31

本文实现了
图片格式随意转换（下拉框选择）；
点击FileUpload立即显示图片（Js实现）的技巧；

第一步：打开页面

第二步：选择一副Jpg格式的图片

第三步：转换为GIF格式，明显看出图片画质降低。

后台代码：

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
        {
        //清清月儿留给大家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 = "转换成功，生成"+NewFilename+"，如下所示。";
            TextBox1.Text = "1";//开始为0，转换后为1
        }
        catch (Exception ex)
        {
            Response.Write(ex);
        }
    }

}

前台代码：
<%@ 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>图片格式转换</title>
    <script language="javascript">
     function show_img()//实现选择图片后立即显示给客户
        {

        if(document.all.TextBox1.value=="0"){//开始为0，转换后为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" onmouseover="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="转换" /></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>