[轉(zhuǎn)]：http://adyhpq.blog.163.com/blog/

剛剛寫了一個(gè)在顯示圖片是加水印的程序(不改變?cè)瓐D片)的程序,寫出來(lái)和大家分享一下,也許有的人已經(jīng)早就會(huì)了

原理很簡(jiǎn)單,就是攔截HTTP請(qǐng)求,寫一個(gè)HttpHandler,首先我在web.config里面配置了圖片的根路徑:

<appSettings>

??? <add key="monitorPath" value="pictures"/>

?</appSettings>

這個(gè)pictures是放所有圖片的地方,包括下面的文件夾,從這里顯示的圖片都要加上水印.

然后寫一個(gè)類,繼承HttpHandler,這個(gè)類將自動(dòng)放在AppCode下面,如下:

public class ShuiyinHandler:IHttpHandler

{

??? public bool IsReusable

??? {

??????? get { return true; }

??? }

??? public void ProcessRequest(HttpContext context)

??? {

??????? try

??????? {

??????????? //得到請(qǐng)求路徑

??????????? string url = context.Request.Url.AbsoluteUri.ToLower();

??????????? string monitorPath = ConfigurationManager.AppSettings["monitorPath"];

??????????? //是否包含圖片路徑

??????????? bool IsInterestUrl = url.Contains(monitorPath);

??????????? System.Drawing.Image imgSource = null;

???????????

????????????? //判斷原圖片是否存在

??????????? string physicalPath = context.Request.PhysicalPath;

??????????? if (!System.IO.File.Exists(physicalPath))

??????????? {

??????????????? context.Response.Write("圖片不存在");

??????????????? return;

??????????? }

??????????? //如果不是要加水印的文件或文件夾,就原樣輸出

??????????? if (!IsInterestUrl)

??????????? {

??????????????? imgSource = System.Drawing.Image.FromFile(physicalPath);

??????????????? imgSource.Save(context.Response.OutputStream, imgSource.RawFormat);

??????????????? imgSource.Dispose();

??????????????? return;

??????????? }

??????????? imgSource = System.Drawing.Image.FromFile(physicalPath);

??????????? //判斷是否是索引圖像格式

??????????? if (imgSource.PixelFormat == PixelFormat.Format1bppIndexed || imgSource.PixelFormat == PixelFormat.Format4bppIndexed || imgSource.PixelFormat == PixelFormat.Format8bppIndexed)

??????????? {

??????????????? //轉(zhuǎn)成位圖,這步很重要

??????????????? Bitmap bitmap = new Bitmap(imgSource.Width, imgSource.Height);

??????????????? System.Drawing.Graphics graphic = System.Drawing.Graphics.FromImage(bitmap);

??????????????? System.Drawing.Font font = new System.Drawing.Font("Arial Black", 30.0f, System.Drawing.FontStyle.Bold);

??????????????? //將原圖畫在位圖上

??????????????? graphic.DrawImage(imgSource, new Point(0, 0));

??????????????? //將水印加在位圖上

??????????????? graphic.DrawString("www.dgxyt.com", font, System.Drawing.Brushes.Red, new System.Drawing.PointF());

??????????????????? //將位圖輸入到流

??????????????? bitmap.Save(context.Response.OutputStream, ImageFormat.Jpeg);

??????????????? graphic.Dispose();

??????????????? imgSource.Dispose();

??????????????? bitmap.Dispose();

??????????? }

??????????? else

??????????? {

??????????????? //不是索引圖像格式,直接在上面加上水印

??????????????? System.Drawing.Graphics graphic = System.Drawing.Graphics.FromImage(imgSource);

??????????????? System.Drawing.Font font = new System.Drawing.Font("Arial Black", 30.0f, System.Drawing.FontStyle.Bold);

??????????????? graphic.DrawString("www.dgxyt.com", font, System.Drawing.Brushes.Red, new System.Drawing.PointF());

??????????????? imgSource.Save(context.Response.OutputStream, System.Drawing.Imaging.ImageFormat.Jpeg);

??????????????? imgSource.Dispose();

??????????????? graphic.Dispose();

??????????? }

??????????? //標(biāo)明類型為jpg：如果不標(biāo)注，IE沒(méi)有問(wèn)題，但Firefox會(huì)出現(xiàn)亂碼

??????????? context.Response.ContentType = "image/jpeg";

??????????? context.Response.Flush();

??????????? context.Response.End();

??????? }

??????? catch

??????? {

??????????? throw;

??????? }

??? }

}

?

這樣HttpHandler寫好了,在web.config中中的HttpHandler節(jié)點(diǎn)下,加下如下代碼:

<httpHandlers>

????? <add verb="*" path="*.jpg,*.bmp,*.ico,*.jpeg" type="ShuiyinHandler"/>

? </httpHandlers>

?

這表示,jpg,bmp,ico,jpeg都可以加上水印,gif沒(méi)有試過(guò),不過(guò)大家可以試下.

?

寫好之后,放在IIS上,居然不出來(lái)加水印的效果,這讓我郁悶了好久,后來(lái)終于找到原因,原來(lái)是沒(méi)有在IIS上沒(méi)有注冊(cè)以jpg,bmp,ico,jpeg為后綴的文件,IIS默認(rèn)是不處理這些文件的。

?

處理方法：在網(wǎng)站上目錄上右擊，選擇屬性,選擇主目錄,配置，

隨便選擇列表中的一行，點(diǎn)擊編緝，復(fù)制執(zhí)行文件的路徑，然后關(guān)閉，再點(diǎn)擊添加，可執(zhí)行文件用粘貼就可以了，后綴名寫上.jpg，點(diǎn)擊確定。按此方法再添加其他后綴名。

?

這樣就實(shí)現(xiàn)水印效果了。

轉(zhuǎn)載于:https://www.cnblogs.com/sainaxingxing/archive/2008/09/03/1283303.html

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