asp.net上传图片并作处理水印与缩略图的实例代码

方法类：

upfileclass.cs

using system;
using system.data;
using system.configuration;
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;

/// <summary>
/// upfileclass 的摘要说明
/// </summary>
public class upfileclass
{
    public upfileclass()
    {
        //
        // todo: 在此处添加构造函数逻辑
        //
    }

    /// <summary>
    /// 生成缩略图
    /// </summary>
    /// <param name="originalimagepath">源图路径（物理路径）</param>
    /// <param name="thumbnailpath">缩略图路径（物理路径）</param>
    /// <param name="width">缩略图宽度</param>
    /// <param name="height">缩略图高度</param>
    /// <param name="mode">生成缩略图的方式</param>
    public static void makethumbnail(string originalimagepath, string thumbnailpath, int width, int height, string mode)
    {
        system.drawing.image originalimage = system.drawing.image.fromfile(originalimagepath);

        int towidth = width;
        int toheight = height;

        int x = 0;
        int y = 0;
        int ow = originalimage.width;
        int oh = originalimage.height;

        switch (mode)
        {
            case "hw"://指定高宽缩放（可能变形）
                break;
            case "w"://指定宽，高按比例
                toheight = originalimage.height * width / originalimage.width;
                break;
            case "h"://指定高，宽按比例
                towidth = originalimage.width * height / originalimage.height;
                break;
            case "cut"://指定高宽裁减（不变形）
                if ((double)originalimage.width / (double)originalimage.height > (double)towidth / (double)toheight)
                {
                    oh = originalimage.height;
                    ow = originalimage.height * towidth / toheight;
                    y = 0;
                    x = (originalimage.width - ow) / 2;
                }
                else
                {
                    ow = originalimage.width;
                    oh = originalimage.width * height / towidth;
                    x = 0;
                    y = (originalimage.height - oh) / 2;
                }
                break;
            default:
                break;
        }

        //新建一个bmp图片
        system.drawing.image bitmap = new system.drawing.bitmap(towidth, toheight);

        //新建一个画板
        system.drawing.graphics g = system.drawing.graphics.fromimage(bitmap);

        //设置高质量插值法
        g.interpolationmode = system.drawing.drawing2d.interpolationmode.high;

        //设置高质量,低速度呈现平滑程度
        g.smoothingmode = system.drawing.drawing2d.smoothingmode.highquality;

        //清空画布并以透明背景色填充
        g.clear(system.drawing.color.transparent);

        //在指定位置并且按指定大小绘制原图片的指定部分
        g.drawimage(originalimage, new system.drawing.rectangle(0, 0, towidth, toheight),
        new system.drawing.rectangle(x, y, ow, oh),
        system.drawing.graphicsunit.pixel);

        try
        {
            //以jpg格式保存缩略图
            bitmap.save(thumbnailpath, system.drawing.imaging.imageformat.jpeg);
        }
        catch (system.exception e)
        {
            throw e;
        }
        finally
        {
            originalimage.dispose();
            bitmap.dispose();
            g.dispose();
        }
    }

    /// <summary>
    /// 在图片上增加文字水印
    /// </summary>
    /// <param name="path">原服务器图片路径</param>
    /// <param name="path_sy">生成的带文字水印的图片路径</param>
    public static void addshuiyinword(string path, string path_sy)
    {
        string addtext = "爱智旮旯";
        system.drawing.image image = system.drawing.image.fromfile(path);
        system.drawing.graphics g = system.drawing.graphics.fromimage(image);
        g.drawimage(image, 0, 0, image.width, image.height);
        system.drawing.font f = new system.drawing.font("verdana", 16);
        system.drawing.brush b = new system.drawing.solidbrush(system.drawing.color.blue);

        g.drawstring(addtext, f, b, 15, 15);
        g.dispose();

        image.save(path_sy);
        image.dispose();
    }

    /// <summary>
    /// 在图片上生成图片水印
    /// </summary>
    /// <param name="path">原服务器图片路径</param>
    /// <param name="path_syp">生成的带图片水印的图片路径</param>
    /// <param name="path_sypf">水印图片路径</param>
    public static void addshuiyinpic(string path, string path_syp, string path_sypf)
    {
        system.drawing.image image = system.drawing.image.fromfile(path);
        system.drawing.image copyimage = system.drawing.image.fromfile(path_sypf);
        system.drawing.graphics g = system.drawing.graphics.fromimage(image);
        g.drawimage(copyimage, new system.drawing.rectangle(image.width - copyimage.width, image.height - copyimage.height, copyimage.width, copyimage.height), 0, 0, copyimage.width, copyimage.height, system.drawing.graphicsunit.pixel);
        g.dispose();

        image.save(path_syp);
        image.dispose();
    }
}
 

default.aspx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>asp.net 上传图片并作处理 水印 缩略图</title>
</head>
<body>
    <form id="form1" runat="server">
   <div>
        <asp:fileupload id="fileupload1" runat="server" bordercolor="gray" borderwidth="1px" />
        <asp:button id="button1" runat="server" onclick="button1_click" text="上传" bordercolor="gray" borderwidth="1px" width="70px" /><br />
        <asp:label id="label1" runat="server"></asp:label>
   </div>
    </form>
</body>
</html>
 

default.aspx.cs代码：
 

using system;
using system.data;
using system.configuration;
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;

public partial class _default : system.web.ui.page
{
    protected void page_load(object sender, eventargs e)
    {

    }
    protected void button1_click(object sender, eventargs e)
    {
        if (fileupload1.hasfile)
        {
            string filecontenttype = fileupload1.postedfile.contenttype;
            if (filecontenttype == "image/bmp" || filecontenttype == "image/gif" || filecontenttype == "image/pjpeg")
            {
                string name = fileupload1.postedfile.filename; // 客户端文件路径

                fileinfo file = new fileinfo(name);
                string filename = file.name; // 文件名称
                string filename_s = "s_" + file.name; // 缩略图文件名称
                string filename_sy = "sy_" + file.name; // 水印图文件名称（文字）
                string filename_syp = "syp_" + file.name; // 水印图文件名称（图片）
                //以下路径可以根据情况进行修改
                string webfilepath = server.mappath("file/" + filename); // 服务器端文件路径
                string webfilepath_s = server.mappath("file/" + filename_s);　　// 服务器端缩略图路径
                string webfilepath_sy = server.mappath("file/" + filename_sy);　// 服务器端带水印图路径(文字)
                string webfilepath_syp = server.mappath("file/" + filename_syp);　// 服务器端带水印图路径(图片)
                //以下为水印图片的路径一定要先准备一张水印图片！
                string webfilepath_sypf = server.mappath("file/shuiyin.jpg");　// 服务器端水印图路径(图片)

                if (!file.exists(webfilepath))
                {
                    try
                    {
                        fileupload1.saveas(webfilepath); // 使用 saveas 方法保存文件
                        upfileclass.addshuiyinword(webfilepath, webfilepath_sy);
                        upfileclass.addshuiyinpic(webfilepath, webfilepath_syp, webfilepath_sypf);
                        upfileclass.makethumbnail(webfilepath, webfilepath_s, 130, 130, "cut"); // 生成缩略图方法
                        label1.text = "提示：文件“" + filename + "”成功上传，并生成“" + filename_s + "”缩略图，文件类型为：" + fileupload1.postedfile.contenttype + "，文件大小为：" + fileupload1.postedfile.contentlength + "b";
                    }
                    catch (exception ex)
                    {
                        label1.text = "提示：文件上传失败，失败原因：" + ex.message;
                    }
                }
                else
                {
                    label1.text = "提示：文件已经存在，请重命名后上传";
                }
            }
            else
            {
                label1.text = "提示：文件类型不符";
            }

        }
    }

}