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The author:(作者)delvpublished in(发表于) 2014/1/23 3:10:57 ASP.NET中通过对话框方式下载文件_[Asp.Net教程]
ASP.NET中通过对话框方式下载文件
1 通过探出对话框提示文件下载或打开
2 通过自定义Header让特定的应用程序打开文件
使用的方法:Response.TransmitFile()
例程:
Response.ContentType = “image/jpeg”;Response.AppendHeader(“Content-Disposition”,”attachment; filename=SailBig.jpg”);Response.TransmitFile( Server.MapPath(“~/images/sailbig.jpg”) );
流传送所使用的方法:
Response.BinaryWrite()和Response.OutputStream()
Bitmap bmp = wwWebUtils.CornerImage(backcolor, color, c, Radius, Height, Width);Response.ContentType = “image/jpeg”;Response.AppendHeader(“Content-Disposition”,”attenment; filename=LeftCorner.jpg”);bmp.Save(Response.OutputStream, ImageFormat.Jpeg);
关于Content Type(MIME Type)的参考URL:
http://www.w3.org/TR/html4/types.html (概述)
http://www.iana.org/assignments/media-types/ (详细列表)
常见问题解决方案:
1、当从资源文件或者数据库BLOB字段载入图像出现错误
错误内容:A generic error occurred in GDI+
代码:
Bitmap bmp = this.GetGlobalResourceObject(“Resource”,”_BitMap”) as Bitmap; Response.ContentType=”image/jpeg”;bmp.Save(Response.OutputStream, ImageFormat.Jpeg); Response.End();
解决方法,再创建一个实例接收从资源文件或者数据库BLOB字段读入的图像内容。
解决方案代码:
Bitmap bmp = this.GetGlobalResourceObject(“Resource”, ”_BitMap”) as Bitmap;Bitmap temp = new Bitmap(bmp); Response.ContentType = “image/jpeg”;Temp.Save(Response.OutputStream, ImageFormat.Jpeg); bmp.Dispose();temp.Dispose(); Response.End(); 2、无法直接把PNG图像存入到输出流
原因:PNG是特殊的图片格式
Bitmap bmp = this.GetGlobalResourceObject( “Resource”, “_BitMap”) as Bitmap;Bitmap temp = new Bitmap(bmp); MemoryStream ms = new MemoryStream(); Response.ContentType=”image/png”;temp.Save(ms, System.Drawing.Imaging, ImageFormat.Png);Ms.WriteTo(Response.OutputStream); bmp.Dispose();temp.Dispose(); Response.End();
3、解决缓存问题
Response.ContentType=”image/png”;Response.Buffer = false;Response.Clear(); MemoryStream stream1 = new MemoryStream(); // DrawPie method return an ImageThis.DrawPie(table1).Save(stream1,ImageFormat.Png);Response.BinaryWrite(stream1.ToArray()); Base.OnPreInit(e);
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