Implementation method and attention __JS of JSP download file

Source: Internet
Author: User
Tags save file
Implement file download in JSP

A
The easiest way is to do hyperlinks on the Web page, such as: <a href= "Music/abc.mp3" > click Download </a>.
However, the directory resources on the server will be exposed directly to the end user, which will bring some unsafe factors to the website.

So there are other ways to download it, and you can use:

1, the way of RequestDispatcher;

2, the use of file flow output mode download. Recommended



1, the use of RequestDispatcher way to carry out

JSP Code    <%     response.setcontenttype ("Application/x-download"); Set to download application/x-download     String filedownload =  "/file name to download";/ The relative path of the file to be downloaded      String filedisplay =  the "save file name to be displayed to the user eventually";//File save names displayed when downloading files      string filenamedisplay = urlencoder.encode (Filedisplay, "UTF-8");      response.addheader ("Content-disposition", "attachment;filename="  + filedisplay);            try     {      Requestdispatcher dis = application.getrequestdispatcher (filedownload);      if (dis!= null)      {     dis.forward (request,response);     }     response.flushbuffer ();     }      catch (exception e)      {     e.printstacktrace ();     }      finally     {           }  %>   

2, the use of file flow output mode download

JSP code    <% @page  language= "java"  contenttype= "Application/x-msdownload"  pageencoding = "gb2312"%>   <%     //processing:   with file stream output in the case of file downloads   // Add Response.reset (), and do not wrap all%> behind, including the last;        response.reset (), or you can add or not      response.setcontenttype ("Application/x-download");     // Application.getrealpath ("/main/mvplayer/capsetup.msi"); physical path acquired       string filedownload  =  "Think of ways to find the physical path to download files + filename";    String filedisplay =  "to provide users with the download file name";      string filedisplay = urlencoder.encode (Filedisplay, "UTF-8");      response.addheader ("Content-disposition", "attachment;filename="  + filedisplay);         java.io.OutputStream outp = null;      Java.io.fileinputstream in = null;     try     {     outp =  response.getoutputstream ();     in = new fileinputstream ( Filenamedownload);        byte[] b = new byte[1024];      int i = 0;        while (I = in.read (b) )  > 0      {     outp.write (b, 0, i);     }  //     Outp.flush ();  //To be the next two words, or you will be the error   // Java.lang.illegalstateexception: getoutputstream ()  has already been called for  //this response     out.clear ();   out = pagecontext.pushbody ();  }     catch (exception 
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