ASP. NET study note _ 06 httphandler

1. httphandler

Instance 1: generate a dynamic image to output the Client IP address, operating system type, and browser type.

<% @ Webhandler Language = "  C #  " Class = "  Visitor  " %> Using  System;  Using  System. Web;  Public   Class  Visitor: ihttphandler { Public   Void  Processrequest (httpcontext context) {context. response. contenttype = "  Image/JPEG  "  ;  Using (System. Drawing. Bitmap bitimage = New System. Drawing. Bitmap ( 330 , 300  )){  //  Set canvas             Using (System. Drawing. Graphics G = System. Drawing. Graphics. fromimage (bitimage )){  //  IP G. drawstring ( "  IP:  " + Context. Request. userhostaddress, New System. Drawing. Font ( "    " , 20 ), System. Drawing. Brushes. Red, New System. Drawing. pointf ( 0 , 0  ));  //  Operating System G. drawstring ( "  Operating System:  " + Context. Request. browser. platform, New System. Drawing. Font ( "    " , 20 ), System. Drawing. Brushes. Red,New System. Drawing. pointf ( 0 , 50  ));  //  Browser G. drawstring ( "  Browser:  " + Context. Request. browser. type, New System. Drawing. Font ( "    " , 20 ), System. Drawing. Brushes. Red, New System. Drawing. pointf ( 0 , 100  ));}  //  Save to output stream  Bitimage. Save (context. response. outputstream, system. Drawing. imaging. imageformat. JPEG );}}  Public   Bool  Isreusable {  Get  {  Return  False  ;}}} 

Instance 2: Click Download to connect. The user attachment is saved.

HtmlCode: <A href = "dowload. ashx"> download </a>

<% @ Webhandler Language = "  C #  " Class = "  Dowload  " %> Using  System;  Using  System. Web;  Public  Class  Dowload: ihttphandler {  Public   Void  Processrequest (httpcontext context ){  String Filename = httputility. urlencode ( "  Tragedy .jpg  "  ); Context. response. contenttype = "  Image/JPEG  "  ;  // Open the header and set its value in the attachment dialog box. Context. response. addheader ( "  Content-Disposition  " , "  Attachment: filename =  " + Filename); context. response. writefile (  "  Apple .jpg  "  );}  Public   Bool Isreusable {  Get  {  Return   False  ;}}}