How to force browser to download file

Question

Everything works fine  but only if file is small  about 1MB  when I tried it with bigger files  like 20MB my browser display it  instead of force to download  I tried many headers so far  now my code looks   PrintWriter out   response getWriter    String fileName   request getParameter  filename     File f  new File fileName    InputStream in   new FileInputStream f   BufferedInputStream bin   new BufferedInputStream in   DataInputStream din   new DataInputStream bin    while din available    gt  0       out print din readLine         out print   n       response setContentType  application force-download    response setContentLength  int f length     response setHeader  Content-Transfer-Encoding    binary    response setHeader  Content-Disposition   attachment  filename        xxx       fileName     in close    bin close    din close

User · Answer

Set content-type and other headers before you write the file out  For small files the content is buffered  and the browser gets the headers first  For big ones the data come first

User · Answer

This is from a php script which solves the problem perfectly with every browser I ve tested  FF since 3 5  IE8   Chrome   header  Content-Disposition  attachment  filename      fname local        header  Content-Type  application force-download    header  Content-Transfer-Encoding  binary    header  Content-Length    filesize  fname      So as far as I can see  you re doing everything correctly  Have you checked your browser settings

User · Answer

You are setting the response headers after writing the contents of the file to the output stream  This is quite late in the response lifecycle to be setting headers  The correct sequence of operations should be to set the headers first  and then write the contents of the file to the servlet s outputstream   Therefore  your method should be written as follows  this won t compile as it is a mere representation    response setContentType  application force-download    response setContentLength  int f length               response setContentLength -1   response setHeader  Content-Transfer-Encoding    binary    response setHeader  Content-Disposition   attachment  filename        xxx       fileName           File f  new File fileName    InputStream in   new FileInputStream f   BufferedInputStream bin   new BufferedInputStream in   DataInputStream din   new DataInputStream bin    while din available    gt  0       out print din readLine         out print   n        The reason for the failure is that it is possible for the actual headers sent by the servlet would be different from what you are intending to send  After all  if the servlet container does not know what headers  which appear before the body in the HTTP response   then it may set appropriate headers to ensure that the response is valid  setting the headers after the file has been written is therefore futile and redundant as the container might have already set the headers  You could confirm this by looking at the network traffic using Wireshark or a HTTP debugging proxy like Fiddler or WebScarab   You may also refer to the Java EE API documentation for ServletResponse setContentType to understand this behavior      Sets the content type of the response being sent to the client  if the response has not been committed yet  The given content type may include a character encoding specification  for example  text html charset UTF-8  The response s character encoding is only set from the given content type if this method is called before getWriter is called       This method may be called repeatedly to change content type and character encoding  This method has no effect if called after the response has been committed

[java] How to force browser to download file?

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